Rain Water Harvesting

kryan1 · 16-04-2014 7:37pm #1

I was thinking of putting down a tank to collect the rain water and i am at the moment in the process of piping all the down pips to 1 location as currently they are just run off the footpaths.
My question is should i put a filter or something before the water goes into the tank. The was is not going to be for consumption, it will be for out door use and for the hot water in the house.
I was looking on line and there are filters but they are only like glorified leaf filters and they are expensive. i know in the long run it will keep big dirt out of the tank but is it worth it
Has anyone got one, seen 1, recommend 1?
is there a simpler means, like if i made something up my self? any advise would be greatly appricated.

many thanks

Kevin

slimjimmc · 16-04-2014 8:28pm

Perhaps you could make a simple dirt trap using a container with the inlet at the top and the outlet high on the side. Heavy grit and sludge would settle below the outlet you can clean it out as needed. If you leave the top open you could just lay a piece of mesh across to catch leaves. Might not be pretty though.

kryan1 · 16-04-2014 8:55pm

slimjimmc wrote: »

Perhaps you could make a simple dirt trap using a container with the inlet at the top and the outlet high on the side. Heavy grit and sludge would settle below the outlet you can clean it out as needed. If you leave the top open you could just lay a piece of mesh across to catch leaves. Might not be pretty though.

Yea I know exactly what u meat. Great suggestion.... Thanks....

kryan1 · 19-06-2014 8:31am

Has anyone made a small settling tank for their rainwater harvesting system. I am looking for a small tank that would catch the majority of d sediment and dirt before it goes into the main tank, has anyone any thought r ideas how to do this? I was thinking of using a farm watering trough and make a cover for it?

I am also curious about what pump I should use for the rain harvesting system. I was planning on running a pipe from.the rain.harvesting unit up to the gravity feed tank,.
I was going to T off this pipe and this would be for water outside. Or would I need to run a hose down from the gravity tank to the outside tap.

Appreciate any ideas or thoughts.

Thanks.

jack of all · 19-06-2014 9:31am

I think there is a significant flaw in your system in that you propose to pipe filtered (but untreated) rainwater to your tank, but this will not purify the water and remove microbacteriological contamination, which will create problems in your cold water storage tank and in your hot water cylinder. It would be interesting to do a cost benefit analysis but I reckon the water charge would look cheap when compared with the initial capital cost and ongoing maintenance issues associated with filtering and treating harvested rainwater for use in showering and bathing in the home.

A more realistic solution would be to harvest the rainwater for outdoor use and for flushing toilets only, and even in this case you would need to pipe your toilet cisterns independently. However I have noticed a faint odour from the rain water I have harvested, probably due to the bird droppings, moss and other organic matter that washes off the roof, so it might be something to consider!

kryan1 · 19-06-2014 9:45am

The system will only be used for hot water, toilets outdoor hose and showers. It would not be used for drinking water or anything like that, so I wanted to make a trap to catch the majority of d grit silt that would normally form at d bottom I'd d tank.

jack of all · 19-06-2014 9:59am

kryan1 wrote: »

The system will only be used for hot water, toilets outdoor hose and showers.

Can you not see how using untreated water (that will contain bacteria and organic matter) is a problem; heating it up will accelerate bacteria growth in the hot water cylinder and the cold water storage tank in the attic will warm up in hot weather leading to issues with bacteria. Showering with such water is a serious health risk as the fine water droplets are easily inhaled (think legionnaires disease!). It's a non-runner unless you propose to treat the harvested water.

monseiur · 19-06-2014 12:52pm

Hi
You will require the following,
5,000 Litre water storage tank
Electric water pump + float switch
Water filter on pipe between pump & tank

There are various types of filters on the market, some have a back wash option, others come with ultra violet rays to treat the water, plus the basic simple filter that just traps ''suspended solids''

You can use the existing attic tank, leave everything as is so you'll have it as a stand by/back up in case your resevoir runs dry.
Place the pump beside the storage tank, in a dry, insulated pump house, wire it through a float swithch placed in the attic tank, this will automatically turn on the pump when the water level in the tank falls to a certain level.
Consider bringing a supply from the water main direct to kitchen for cooking, drinking etc.

M.

slimjimmc · 21-06-2014 9:53am

Definitely need a suitably rated UV filter to sterilise the water for any domestic use, and it's still not fit for consumption. Untreated water is only fit for outdoors.

Giving it holly · 22-06-2014 5:25pm

The water in storage will only be there for a short time and will not go stagnant. People seem to be making a big issue of bacteria etc even though they are using mains water not fit for consumption. Studies have shown that harvested water heated to 60 degrees will kill all bacteria in less than 10 minutes. People drank water from barrels under water shoots 30-40 years ago and never got sick. The people living in the cities might not believe this but it is true.

jack of all · 22-06-2014 10:54pm

I'm out.

Sir Arthur Daley · 22-06-2014 11:59pm

kryan1 wrote: »

The system will only be used for hot water, toilets outdoor hose and showers.

You do not have to drink infected water to get infected by Legionnaires disease or Pontiac fever.
A shower is one place one can contract it quite easily.

michael999999 · 23-06-2014 12:05am

Giving it holly wrote: »

The water in storage will only be there for a short time and will not go stagnant. People seem to be making a big issue of bacteria etc even though they are using mains water not fit for consumption. Studies have shown that harvested water heated to 60 degrees will kill all bacteria in less than 10 minutes. People drank water from barrels under water shoots 30-40 years ago and never got sick. The people living in the cities might not believe this but it is true.

So will heating all the harvested water to 60 degrees before using, end up being cheaper than just using metered water?

Sir Arthur Daley · 23-06-2014 12:07am

michael999999 wrote: »

So will heating all the harvested water to 60 degrees before using, end up being cheaper than just using metered water?

I imagine the point he was getting at here is the cylinder would be heated anyway as normal.

Sleeper12 · 23-06-2014 12:29pm

So if the hot water starts to run out & drops below 60% can still kill you!

Btw Food needs to be cooked to 74° for 4 minutes before all the bacteria is dead (any chef will tell you this). How is it that bacteria in water can be killed at 60°?

People did used to drink from barrels & streams years ago & at times some of them died or got I'll. Why do you think we spend millions on treating our drinking water?

monseiur · 23-06-2014 12:46pm

A lab test on harvested water will show if it's fit for purpose. Having certain type of bacteria in the water does not mean it's not fit for human consumption.
Thanks to the liberal application of chemicals the mains water does not contain any bacteria but it's the actual chemicals that are a serious health hazard.
Thanks to our wet climate here,with roofs being washed down almost daily,using harvested from an aged roof is safe when compared to chemical laden mains water.
Of course regular testing of harvested water is advised (once a year)
Using water off a newly constructed house/roof is not advised....better to wait 2 to 3 years to allow the the roof to be thoroughly cleansed.
With water charges coming down the line water harvesting will become more popular - the pay back time is 3 to 6 years depending of size of family etc. etc.
(Bear in mind that only a small fraction of the world's population have access to treated water)

M.

recipio · 23-06-2014 5:08pm

:rolleyes: Remember the poor chap who tested the water of a hot tub ( with his hand ) while house viewing a few years ago ......and died from Legionnaires disease.
I imagine harvesting roof water for human use will depend on industrial grade filtration which is not yet economically viable.

Sleeper12 · 23-06-2014 5:22pm

I'll drink chemically treated mains water any day over rainwater harvested from the roof. I don't care if the roof is only 6 months old let alone 20 years. I wouldn't let my family brush their teeth in water with bird **** in it.

BBelieve it or not some plumbers have trained in rainwater harvesting. When they say legionnaires disease they mean legionnaires disease.

The aaverage house needs 5000 litre tank just to flush toilets & run the washing machine. That's 5 oil tanks. How much water do you think you'd have to store to shower in it too?

zagmund · 24-06-2014 10:57am

We have a 500l (not 5,000) tank which covers us for flushing the toilets for a family of 4 for most of the year. During the recent dry spell we also used it for watering the garden. It only ran dry about 10 days ago. Last time it ran dry was in December (if I remember correctly) when we had an unusually long spell with no rain. We haven't had rain for about 3 weeks or more, so that gives you an idea of how long 500l lasts.

For showering also you would need a huge tank/set of tanks as mentioned above. I don't have the figures to hand, but I think a shower accounts for ~30-50l, so without regular rain you would be running dry every few days even with 1,000l storage.

z

Sleeper12 · 24-06-2014 4:19pm

zagmund wrote: »

We have a 500l (not 5,000) tank which covers us for flushing the toilets for a family of 4 for most of the year. During the recent dry spell we also used it for watering the garden. It only ran dry about 10 days ago. Last time it ran dry was in December (if I remember correctly) when we had an unusually long spell with no rain. We haven't had rain for about 3 weeks or more, so that gives you an idea of how long 500l lasts.

For showering also you would need a huge tank/set of tanks as mentioned above. I don't have the figures to hand, but I think a shower accounts for ~30-50l, so without regular rain you would be running dry every few days even with 1,000l storage.

z

I'm sorry but your maths just don't add up.

Assuming that you have modern toilets & cisterns. 4 people flushing 4 times a day is about 80 litres per day. With a 500 litre tank it'll run empty after just over 6 days.

If you have the old style toilets your tank will run dry after 2 days.

The previous poster obviously is running out of water much more than they think & they don't have an efficient system. Either that or they are not flushing the toilet as much as the average person.

This is why anyone trained in rainwater harvesting has been taught that 5000 litre for the average house.

The 5000 litre per house is for toilet flushing, washing machine & watering garden. This does not include showering because you should not ever use this water for showering without special (expensive uv treatment system. If you had this & you wanted enough water to shower for the whole family you could go up to 7000 / 10000 litre tank.
Op I suggest you post this in the plumbing section as some of the advice you are getting is nonsense. In the plumbing section you will get advice from people trained in rainwater harvesting.

zagmund · 24-06-2014 5:10pm

Yeah, sorry about that - my quantities were wrong. I need to check, but I think it's 500l outside and then a further 500l in the attic. I forgot about the attic tanks. I'm pretty sure about how often we run out of water as there's a big red light that goes on when it's dry and has reverted to mains.

The toilets & cisterns are new and are low volume. While we have 4 people in the house, they are often out at work or school during the day. We didn't plumb in the washing machine or dishwasher as even though we had relatively good filtering, I just couldn't/didn't want to trust the filter in the long term.

We had a lot of rain at the end of May/start of June and before that we had the usual constant rain fall that you would associate with Ireland. I'm not saying that the water we harvested in January was still going in June, just that there was enough rainfall over the weeks and months to keep enough in the tanks to feed the toilets for the 5 or 6 months. I fully expect the red light to be on for much of the summer though as rainfall will obviously be much lower.

z

Sleeper12 · 24-06-2014 5:19pm

zagmund wrote: »

Yeah, sorry about that - my quantities were wrong. I need to check, but I think it's 500l outside and then a further 500l in the attic. I forgot about the attic tanks. I'm pretty sure about how often we run out of water as there's a big red light that goes on when it's dry and has reverted to mains.

The toilets & cisterns are new and are low volume. While we have 4 people in the house, they are often out at work or school during the day. We didn't plumb in the washing machine or dishwasher as even though we had relatively good filtering, I just couldn't/didn't want to trust the filter in the long term.

We had a lot of rain at the end of May/start of June and before that we had the usual constant rain fall that you would associate with Ireland. I'm not saying that the water we harvested in January was still going in June, just that there was enough rainfall over the weeks and months to keep enough in the tanks to feed the toilets for the 5 or 6 months. I fully expect the red light to be on for much of the summer though as rainfall will obviously be much lower.

z

So in short you are not the typical family of 4 as you are out a lot. And you have 1000 litre & not 500 litre. As I saw 500 litre will run dry after 6 days using modern toilets.

YYou should not run dishwasher from rainwater harvesting without expensive uv system. All you should run is washing machine, toilet and watering garden. You need filters for this but for anything more you need an expensive set up. Remembering there is bird poop on your roof then you won't want to run dishwasher, brush your teeth or shower in this water.
Op repost in plumbing section.

BPB · 26-08-2014 2:46am

Rain water Harvesting requires two things for success.
First of all remember that for every Sq meter of any suffice you will get 1 liter of water for every mm of rain, Don’t get hung up on a roof as been your only harvest point you can make free standing collectors or fit along a garden wall
First flush filtering is essential You need a first flush diverter this takes the first rain and diverts it away from your storage.I have a filter before this as well
I Have designed my own filter for a hopper head that is made from nothing more than the frost protector you get for plants.
Secondary filtering I have a barrel system with the same material covering the Barrel along with 3
25 micron filters in the first barrel this filters all water to the rest of the barrels. It comes in spotless But they are a back up. Then it is filtered again in a 5 micron sediment filter and a 1 Micron filter.
It then passes trough a UV Sterilising light that damages the DNA of any bacterial left after the 1 micron filter .
Its used for everything You will find lots of information and how to go about setting up a system on line. I happen to be in the trade.
I bought nothing here in Ireland apart from Barrels and plumbing fittings Everything else was bought on E bay as I found the price of filters and the required UV well over priced and the pump to get it to the loft . on example 1 25 Micron filter in local plumbing supplies 7.30 Euro a box on 10 on E bay 30.00 euro So shop around
So far its cost me about 400 euros At the moment I have a 2000 L storage. But I intend adding more.
The problem I found was that while most companies will provide a storage tank They will not fit trough the front door of the average house apart from the way over the top prices they are asking for them. So for me the plastic Drum was the easy option the 200L ones you can get for around 20 Euro second hand.
The problem is storage I can tell from experience that looking at water coming out the overflow of your rain water storage tell you only one thing you should have more storage capacity .in the recent heavy rain falls in Dublin. The storage I have was overflowing after ½ an hour.
As for is it worth it well every gallon of water you are not paying a water company for saves you money, Lets face it the price of your water is not going to come down it can only go up.. Its designed that way
If you require any help contact me But most of all have a look on line some great info on YouTube

cerastes · 26-08-2014 3:56am

Ive a tank outside to store captured water and a barrel which may be used, I'll probably get a water butt to make it look tidier but nothing is set up.

All I intend to do is catch water for flushing toilets and gardening use or maybe washing the car at least initially as they are big consumption points of water where a lower level of treatment would suffice compared to water for drinking,bathing or washing dishes.
While I dont intend it ever capture water for drinking/cooking/dishwasher
I may consider it for washing clothes if I find out its acceptable.

While Im not planning on doing the minimum level of treatment, I am wondering on what the minimum level of treatment is for flushing toilets/maybe washing clothes as I gather they would require less treatment then all the others.
As I wouldnt want water going stagnant or leaving stagnant residue in a seperate attic tank. While Id consider there would be a high volume of water going through such a tank, Id still have the main tank for supplying all the other cold water needs that are fed from the tank .

My main problem is, how to control the pump to pump up the water and ensure the mains supply kicks in to top up the tank if it goes to a low level. I couldnt locate a high level float switch like a ball cock type that has a circuit connection in it to complete a circuit to tell a pump to stop or to operate a relay and Im not sure what type of low level switch would do. Ive come across capacitive and other sensors myself through work but that adds an extra element of electronics where I wanted to keep it electrical ( a low voltage 12/24v side holding a relay open to supply the mains for the pump) I didnt want to just throw a floating switch over the side, and while I did come across some industrial stuff online, I wasnt certain of the price or whether it'd be even available in small quantities.

Im thinking of diverting the bathing water output, through a filter and then collect it in a main tank where rainwater is also collected and filter/pump/treat automatically all up to a storage tank using float switches, where demand is met by gravity to the toilets.

Id use double non return to isolate the mains providing the backup supply and maybe some form of tundish design to isolate the stored tank water from the untreated supply.

problems, other than getting the time to do it.
I think 50 litres per day per adult for flushing toilets is a reasonable figure by 2, plus 1/2 that for children would work out at 150 litres per day or 1000 litres per week, when its raining a moderate sized roof would fill that, if as mentione 1m^2 provides 1 litre for every 1mm, I did a calculation based on the low rainfall of Jun this year of 31.7mm in one weather station on a 30m squared roof would provide 10k litres in a month or 2500 litres per week. Ive been told by people who collect rain in waterbutts that they fill up rapidly once it rains and they are usually 150-200 litres so 1000litres is only going to take a bit longer, in drier weather, bathing can consume 30-125 litres per person or about 120-350-500litres per day, so about another 850-2500-3500 litres depending on usage, and concern for conserving water. A potential total of <2000 litres usage-3500-4500 litres per week, I sued the lowest rainfall of the year to come to the figures for rainwater collection, if the run off from bathing is used that could offset the clean supplied drinking water being used (eliminates) for flushing toilets.

jeepers101 · 26-08-2014 7:13am

cerastes wrote: »

My main problem is, how to control the pump to pump up the water and ensure the mains supply kicks in to top up the tank if it goes to a low level. I couldnt locate a high level float switch like a ball cock type that has a circuit connection in it to complete a circuit to tell a pump to stop or to operate a relay and Im not sure what type of low level switch would do. Ive come across capacitive and other sensors myself through work but that adds an extra element of electronics where I wanted to keep it electrical ( a low voltage 12/24v side holding a relay open to supply the mains for the pump) I didnt want to just throw a floating switch over the side, and while I did come across some industrial stuff online, I wasnt certain of the price or whether it'd be even available in small quantities.

TCM in Harolds cross do them ballcock type float switches. Might be a bit easier with a pressure switch at your pump though.

monseiur · 26-08-2014 10:31am

BPB wrote: »

Rain water Harvesting requires two things for success.
First of all remember that for every Sq meter of any suffice you will get 1 liter of water for every mm of rain, Don’t get hung up on a roof as been your only harvest point you can make free standing collectors or fit along a garden wall
First flush filtering is essential You need a first flush diverter this takes the first rain and diverts it away from your storage.I have a filter before this as well
I Have designed my own filter for a hopper head that is made from nothing more than the frost protector you get for plants.
Secondary filtering I have a barrel system with the same material covering the Barrel along with 3
25 micron filters in the first barrel this filters all water to the rest of the barrels. It comes in spotless But they are a back up. Then it is filtered again in a 5 micron sediment filter and a 1 Micron filter.
It then passes trough a UV Sterilising light that damages the DNA of any bacterial left after the 1 micron filter .
Its used for everything You will find lots of information and how to go about setting up a system on line. I happen to be in the trade.
I bought nothing here in Ireland apart from Barrels and plumbing fittings Everything else was bought on E bay as I found the price of filters and the required UV well over priced and the pump to get it to the loft . on example 1 25 Micron filter in local plumbing supplies 7.30 Euro a box on 10 on E bay 30.00 euro So shop around
So far its cost me about 400 euros At the moment I have a 2000 L storage. But I intend adding more.
The problem I found was that while most companies will provide a storage tank They will not fit trough the front door of the average house apart from the way over the top prices they are asking for them. So for me the plastic Drum was the easy option the 200L ones you can get for around 20 Euro second hand.
The problem is storage I can tell from experience that looking at water coming out the overflow of your rain water storage tell you only one thing you should have more storage capacity .in the recent heavy rain falls in Dublin. The storage I have was overflowing after ½ an hour.
As for is it worth it well every gallon of water you are not paying a water company for saves you money, Lets face it the price of your water is not going to come down it can only go up.. Its designed that way
If you require any help contact me But most of all have a look on line some great info on YouTube

Hi BPB
Thanks for your post, it's very helpful.
Perhaps you could advise me, I'm in the process of setting up a water harvesting system similar to what you have. I have a 3,000 Gallon tank in place.
Where on E Bay did you source the sediment filters and UV filter & pump ?
Re. Location of filters in relation to pump : Do you plan to pump the water through these filters or siphon it, or maybe siphon through the sediment filters and have the UV filter on the other side of pump or vice versa ? I'm a bit concerned that if the sediment filters are located between the storage tank and pump the flow of water to the pump could be restricted and cause the pump to burn out.

Thanks,
M.

cerastes · 26-08-2014 11:33am

jeepers101 wrote: »

TCM in Harolds cross do them ballcock type float switches. Might be a bit easier with a pressure switch at your pump though.

Thanks for that,
I plan on feeding up to a storage tank and gravity feed to the toilets, so Im not sure if I have a ballcock opening up in the attic and a pump with a pressure switch at the level or beside the pump, if that would activate the pump or not. The pumps I looked at were very expensive, so I was going to do a budget system, use a lidl pump (has a pump curve on the box showing flow rate and head capacity/ability), I was going to do a head calculation, a pump power calculation and match that/size it to standard components available cheaply, pump,standard domestic piping.

Id planned on having a check valve beside the pump to prevent the pipe draining back past the pump if even partially, I read that somewhere and I considered it myself, not sure again if that would have the effect of limiting any pressure switch, although I suppose I could put a check valve before that switch ie
pump-check valve-pressure switch-(depending on the level of cleaning, either a multistage filter here and straight to the)-ballcock-tank, or a multi stage filter and a UV light, then ballcock-tank.

As much as it might sound otherwise, Im trying to do this with a minimum control level but that is automatic, so a system that
1.supplies water to separate tank in attic for gravity feed to toilets only.
2.when below minimum level in collection water tank outside, switches over to mains supply to fill a set minimum level in the seperate attic water tank from mains pressure, either for a timed flow or by float switch or other sensor operation or both ensuring switching off redundancy.
3.Some means of detecting level (high and low and possibly medium) in this attic tank so it doesnt overflow or run the pump unnecessarily and allow the pump to run and switch off. Either a standard? ballcock and a pressure switch to detect when the ballcock is open/closed) OR a ballcock with an electrical connection in it
4.Timed so it fills by a set time, ie doesnt run if someone flushes a toilet at night, unless an overide is operated (to manually make use of a sudden rain supply when the tank is known to be low)
5. A simple means to show the tank level

monseiur · 26-08-2014 2:32pm

cerastes wrote: »

Thanks for that,
I plan on feeding up to a storage tank and gravity feed to the toilets, so Im not sure if I have a ballcock opening up in the attic and a pump with a pressure switch at the level or beside the pump, if that would activate the pump or not. The pumps I looked at were very expensive, so I was going to do a budget system, use a lidl pump (has a pump curve on the box showing flow rate and head capacity/ability), I was going to do a head calculation, a pump power calculation and match that/size it to standard components available cheaply, pump,standard domestic piping.

Id planned on having a check valve beside the pump to prevent the pipe draining back past the pump if even partially, I read that somewhere and I considered it myself, not sure again if that would have the effect of limiting any pressure switch, although I suppose I could put a check valve before that switch ie
pump-check valve-pressure switch-(depending on the level of cleaning, either a multistage filter here and straight to the)-ballcock-tank, or a multi stage filter and a UV light, then ballcock-tank.

As much as it might sound otherwise, Im trying to do this with a minimum control level but that is automatic, so a system that
1.supplies water to separate tank in attic for gravity feed to toilets only.
2.when below minimum level in collection water tank outside, switches over to mains supply to fill a set minimum level in the seperate attic water tank from mains pressure, either for a timed flow or by float switch or other sensor operation or both ensuring switching off redundancy.
3.Some means of detecting level (high and low and possibly medium) in this attic tank so it doesnt overflow or run the pump unnecessarily and allow the pump to run and switch off. Either a standard? ballcock and a pressure switch to detect when the ballcock is open/closed) OR a ballcock with an electrical connection in it
4.Timed so it fills by a set time, ie doesnt run if someone flushes a toilet at night, unless an overide is operated (to manually make use of a sudden rain supply when the tank is known to be low)
5. A simple means to show the tank level

This is my 2 cents worth !
The check valve you refer is called a non return valve, or a foot valve may do depending on your set up.
As you plan to put a separate tank in the attic you don't need a ballcock or time switch instead fit a float switch. The float switch is designed to turn the pump on automatically when the tank is almost empty, and will automatically switch the pump off when tank is full. Be sure to fit an overflow pipe on tank in case the switch mal functions . So the bigger the tank in the attic the less times the pump will operate, with toilets only, it may be just once daily.
To get the mains water to fill the attic tank when your storage tank is empty during a dry spell etc. you could fit another float switch on storage tank, take a connection off the rising water main and connect to attic tank. Fit a motorised valve on this connection, when the water level falls in the storage tank the float valve will kick in and operate the motorised valve - in other words, it will open the valve allowing water from main into attic tank.
You will need a pressure valve system on tank to close the motorised valve when the attic tank is full
When the rain water fills your storage tank the float switch will close the motorised valve on the rising water main automatically.
It's sounds more complicated than it really is, a simple drawing in this case would speak a 1,000 words !

M.

cerastes · 26-08-2014 5:26pm

monseiur wrote: »

This is my 2 cents worth !
The check valve you refer is called a non return valve, or a foot valve may do depending on your set up.
As you plan to put a separate tank in the attic you don't need a ballcock or time switch instead fit a float switch. The float switch is designed to turn the pump on automatically when the tank is almost empty, and will automatically switch the pump off when tank is full. Be sure to fit an overflow pipe on tank in case the switch mal functions . So the bigger the tank in the attic the less times the pump will operate, with toilets only, it may be just once daily.
To get the mains water to fill the attic tank when your storage tank is empty during a dry spell etc. you could fit another float switch on storage tank, take a connection off the rising water main and connect to attic tank. Fit a motorised valve on this connection, when the water level falls in the storage tank the float valve will kick in and operate the motorised valve - in other words, it will open the valve allowing water from main into attic tank.
You will need a pressure valve system on tank to close the motorised valve when the attic tank is full
When the rain water fills your storage tank the float switch will close the motorised valve on the rising water main automatically.
It's sounds more complicated than it really is, a simple drawing in this case would speak a 1,000 words !

M.

For a start, thanks for the reply and info, my reply to your reply

is,

A picture/wiring diagram would make it easier to understand, if you've any or links, that'd be great. I've a few ideas how I'd do it and am still thinking/figuring what will be compatible with what. Ultimately Id like it controlled by some kind of logic controller (Im thinking integrated with something that has communication in a device already available, alarms, rather than some kind of mini standalone PLC).
Either way, something that could be monitored with a local visual display or output and also operated remotely, but better if it can be done simply and run automatically on its own and overridden and shut off manually too for a start.

I hadn't really intended using float switches but it seems like it might make things easier.
I'd planned on putting lids on any tanks to be used, is there a tidier sealed way to get float switches into the tank (through a sealable grommet? also does any method not put a strain on the insulation on the float switch lead with the movement?), I ruled them out initially because of the lid and didnt like the idea of just bunging them over the side into the tank.

How do you adjust the operation of the float switch? just shorten the amount of wiring in there? for example if I only wanted the mains water to half fill the tank?

Still not sure why I wouldnt want a ballcock or a time switch though,
I would have to bring the supply pipe into the attic and cant see how I can get a valve that operates like a ballcock, which could produce back pressure to switch off a pump? when the tank was full.

What other means do you suggest for connecting the harvested water supply pipe to its attic tank?
I might be misinterpreting you, but I think you mean just put an open ended pipe connected to the tank or flowing in direct or from above?
I could do it through a motorised valve and a float switch, which you suggest for turning on the pump, but the motorised valve is an extra component that might not last as long as a ballcock or be replaced as cheaply, plus it automatically closes when the high level is reached.

And what kind of opening/connection to the tank would be best to operate a pressure switch to run the pump at all and for minimal operation.
As I see it, I need some conditions to be met to determine when the pump will be running.
1. The storage attic tank must be low but not at the low level required for the mains to kick in.
2. The harvested tank outside must have a sufficient level of water to meet at least a minimal demand and preferably enough to meet the complete volume requirement of the attic tank.
3. These conditions may not continue to be met once water is being pumped from one tank to the other so some kind of latching or timed (or combined latching and timed) means may have to be implemented to allow the pump complete its task without switching off.
4. A low level shut off when the harvested supply has run out. (float switch?)
5. A high level shut off when the storage attic tank is full. (float switch and maybe ballcock as a backup). There'd be an overflow as an ultimate backup, but dont want to overflow anything as it will be just a waste having pumped it up there.

The time switch idea was just to overide all electrics normally to prevent operation at night when noise may be more noticeable, unless it's determined it isn't noticeable.

I was always used to calling check valves NRV's, but I've found more people seem to call them check valves in domestic applications so I just stuck with that naming.

edit

Anyone know of a suitable black/dark material to cover a clear tank outside to prevent bio growth from photosynthesis?
Something that can be wrapped around a tank, so a certain flexibility, but durable and resistant to UV (so not bin liners are anything cheap and nasty)

Benster · 27-08-2014 6:05pm

Folks, you have so many ideas similar to my own, it's as if you've been round at my house. I'm at the stage where I'm getting the plumbing sorted out before moving onto the pump control aspect of the project.

I'm collecting in two 210ltr rain barrels, pumping up to a 300ltr separate attic tank using a Lidl submersible pump, feeding two toilets (so far). I'm planning electronic control via float switches, a Raspberry Pi computer and a relay board to control mains electric for the pump.

My mains backup is as follows:

T off the rising main -> Isolator valve -> Non-return valve -> (possibly a small water meter) -> ballcock feed to tank

I have not tested this yet, as I have a problem with the length of the ballcock (careful now!). It's not long enough to extend to near the bottom of the tank so it can kick in when the level is critically low. With the current, standard arm length, it will open when the water is comparitively high in the tank for the purpose I'm using it for, thus will be useless.

I want what rwh_1.jpg shows.

I'm currently getting what rwh_2.jpg shows, which is useless really.

Ideas on how to lengthen the ballcock arm and preserve its strength would be very welcome. This will hopefully spend most of it's time fully submerged and not required to function, so will very likely be under some stress as the float tries to ...float.

I'm hoping not to have to go down the path of electronic control on the mains backup as well, things are complicated enough as it is for what should be a simple enough system.

Cheers.
B.

Benster · 28-08-2014 12:35pm

cerastes wrote: »

Anyone know of a suitable black/dark material to cover a clear tank outside to prevent bio growth from photosynthesis?
Something that can be wrapped around a tank, so a certain flexibility, but durable and resistant to UV (so not bin liners are anything cheap and nasty)

Would the likes of a weed-suppressing fabric as used in the garden be any good? A couple of layers would probably be enough to cover any small holes those fabrics usually have for water drainage.

You should probaly be thinking of some sort of insulating layer for around the whole tank anyway, kind of like a lagging jacket. A week of snow and low temps might be enough to freeze it enough to cause damage. I'm planning this for my own tanks. I'm also insulating the pipe from the tank to the attic with some Kaimann foam from a plumbing suppliers; the pipe is running up the back wall of the house so will definitely be affected by frost is not covered.

HTH.

B.

cerastes · 28-08-2014 2:06pm

Benster wrote: »

Would the likes of a weed-suppressing fabric as used in the garden be any good? A couple of layers would probably be enough to cover any small holes those fabrics usually have for water drainage.

You should probaly be thinking of some sort of insulating layer for around the whole tank anyway, kind of like a lagging jacket. A week of snow and low temps might be enough to freeze it enough to cause damage. I'm planning this for my own tanks. I'm also insulating the pipe from the tank to the attic with some Kaimann foam from a plumbing suppliers; the pipe is running up the back wall of the house so will definitely be affected by frost is not covered.
HTH.
B.

That material could be a good idea, I read that pond liner has been used too, it might be better in that I assume its not permeable to water. I'd prefer if I can source it in a builders providers, I read theres a place in or near Naas that does farm supplies and is a DIY place that does stuff at good prices, not sure of the name or location, I think just off from the globe, if anyone knows where Im referring to, please let me know or reply in the thread.

The insulation could be a good idea, Not sure how frequent a problem it could be, in the event there is extreme cold weather, Id like to be able to turn off the system and drain down the outside filling pipes for overnight, I dont think there would be as much of an issue with pipes used to source and drain harvested water as there wouldnt be any water in them overnight if it went cold. In those situations, Id like to be able to operate it manually, fill up, shut off and drain down again, until the weather.

The possibility of having really cold weather even once a year wouldnt justify trying to implement anything to automatically account for this as I haven't even got started on implementing the harvesting, but I wouldnt rule out having a frost stat in it to prevent pipes bursting from even moderate low temperatures.

To do it automatically would be good, but then I would need a number of some kind of small powered valve, that could be directed to open automatically to drain the system if frost was detected. It would be good if there was something smaller and cheaper in 12v than the type used for plumbing systems as they are quite big. Pnuematically operated would just add another layer of complexity and its own valves.

I dont think the tank would freeze? especially if some sunlight was able to shine over it, Id be more concerned about the piping and at bends/junctions.

What are your opinions/ideas for the harvested supply water to the storage tank? I was thinking that just having the open end of pipe flowing in isn't great, I'd thought of having some kind of a ball valve, simpler and the potential to be less problematic regarding failure.

I also may have mistaken what people meant by float switch, I thought people were suggesting one of those switches that floats like on some of those pumps you see in lidl. I think people might have meant something that mounts into the tank inside wall and is activated when the water level reaches and passes its position.

Benster · 28-08-2014 4:18pm

Regarding float switches, this is what I am referring to:

http://www.reuk.co.uk/buy-FLOAT-SWITCH.htm

BTW, that REUK site is a goldmine of info for RWH.

As for the RW supply, at the moment my supply pipe is terminating at a simple tank connector, nothing else. It will just dump into the tank at the point where it is mounted. I must stress that none of this has had water through it yet, so I may have to modify that to maybe put a calmed inlet on it instead.

Is that what you were wondering about regarding the supply?

cerastes · 30-08-2014 12:13am

Benster wrote: »

Regarding float switches, this is what I am referring to:

http://www.reuk.co.uk/buy-FLOAT-SWITCH.htm

BTW, that REUK site is a goldmine of info for RWH.

As for the RW supply, at the moment my supply pipe is terminating at a simple tank connector, nothing else. It will just dump into the tank at the point where it is mounted. I must stress that none of this has had water through it yet, so I may have to modify that to maybe put a calmed inlet on it instead.

Is that what you were wondering about regarding the supply?

Good link, I actually found that site already and I realised that they are float switches and this was what I was talking about, but I was wondering if someone (maybe you) had mentioned about float switches and was referring to the type that are attached to motors like some of the ones you see in Lidl.
I was looking at their sensor they have as a DIY, with the coils of wire.

That site has some good info on circuits too, I was weighing the possibility of doing some of the control side of things in 12v and have relays to operate a motor, or even to switch on a pump on a circuit that has a solar charged battery.
I was thinking of collecting grey water too, but there may be enough in rainwater, the greywater side would complicate things more, I was looking at slow sand/gravel bed? filters but I think it would be too slow and they'd be ineffective at dealing with a large volume of water if arrived in one go.
Neither do I have the room to have loads of water storage and a sizeable tank would have to be kept away from the house where there is some unused space, meaning, Id have a bit of pipe and wiring work to do and trying to figure how to pump from it to the attic.

As for the open ended pipe from the HRW, not sure how that would best be terminated, a calmed outlet would mean submerging the outlet there? at that point Id have thought the water is sediment and carbon filtered and maybe even had UV on it, so I thought the calmed inlet was for where the water was collected initially?

Not sure on a first flush system either, as again the filtration would be in place. Id expect to have a few mesh strainers to get out the bigger contaminants, like leaves,twigs, anything dropped on the roof by birds, clumps of moss and then the sediment and carbon filter to catch and contain the rest.

Whatever I do on the control side Id like to have most of the electrics in one place in its own enclosure, with the minimal amount outside that.

Haldane · 24-01-2015 12:05am

Benster,
Your project is exactly what I plan on doing albeit for an outside shed for livestock. Basically I just want to pump water up to a header tank from a tank on the ground outside collecting rain water. I have the same idea as yourself and have a Pi sitting about doing nothing so was thinking of using that. i have a mains connection to the shed as well so it's basically the same setup required as yourself. i would be interested in hearing the specs you have for the pump, float switches and solenoid valves.

Rather than extending your ballcock are you can just add a soleoind valve on the inlet so when there is no water in your butt tank and the water level goes below your low level float then you just open the solenoid of the mains.

Be interested to hear how far you have got with the project.

Note the only reason i'm thinking of using the PI and not fully electronic control is cost, something to play with and can see status on my phone.

Regards

Benster · 26-01-2015 12:47pm

Haldane,
Stay tuned for a progress post, it's been operational since Jan 1st, going well so far... I want to get a few photos done before I start writing.

B.

kryan1 · 29-06-2015 6:24pm

If I had a rainwater tank and had a submergible pump that had a pressure switch. Up at the header tank there would be a level switch. This level switch operated the motorised value beside the take. When the level goes low, the motorise valve opens and the pressure in the pipe drops and the pump engages. If the rainwater tank is empty and the pump does not come on as there is a float switch when the water level in the header tank reached a second lower lever this operated a second motorised valve that is connected to the mains water? Is this possible?
Also would it be possible to connect a garden hose by tee off the main hose between the pump and header tank.

youtube! · 29-06-2015 6:54pm

Off topic but I just wanted to say that when I got my reverse osmosis system installed the guy tested the purity of the water with what is known as a TDS meter (total dissolved solids) I decided to buy myself one of these meters and out of curiosity I measured the TDS on several different types of water including rainwater. This is what I found

Normal tap water 550-650 ppm

Reverse Osmosis filtered water 35-45 ppm

Ballygowan 400-550 ppm (yes I couldn't believe it either but true and from several different samples

Evian 80-110 ppm

Deep river rock 250-300 ppm

and finally.... the rainwater which had gathered in my Dog's container which is just an upturned kennel lid.... 12-18ppm , never more than that, so practically pure of TDS and the dog will only drink from this, when we give her tap water she turns her nose up to it every time.

I guess this doesn't save you from bacterial infection however but the dog has been drinking it for yrs with no issues.

bonzodog2 · 29-06-2015 9:45pm

Interesting; can you test boiled tap water and rainwater off your roof?

positron · 30-06-2015 11:50pm

This thread got me reading up on TDS meters, and this is probably common knowledge but I initially misunderstood TDS reading as the "purity" of the water, but found the following online:

What Does a TDS Meter Actually Detect?

Since TDS meters are often used to test water "purity," it is important to understand what they do not detect. As conductivity meters in disguise, TDS meters will only detect mobile charged ions. They will not detect any neutral (uncharged) compounds. Such compounds include sugar, alcohol, many organics (including many pesticides and their residues), and unionized forms of silica, ammonia, and carbon dioxide. These meters also do not detect macroscopic particulates, as those are too large to move in the electric fields applied. So if you see "rusty" looking water from iron oxide particulates, that won't be measured. Neither will anything else that makes the water look cloudy. Bacteria and viruses also won't be detected.

It is a useful reading, but it doesn't necessarily tell you if the water safe for consumption.. Having said that I would not have any issues using rainwater for anything other drinking.

brightspark · 01-07-2015 10:25am

Without knowing what particles are in the water knowing the TDS isn't useful (unless you are maintaining steam boilers etc.)

The ballygowan water TDS reading is high because it is a mineral water, full of non-harmful minerals, some of which may even be beneficial to us such as calcium (114mg/litre) according to their website there is 400mg/litre of bicarbonate in it too, as well as some other minerals.
(I'm guessing that it will get your kettle covered in lime scale if you used it)

Which means that without putting it in the proper context a TDS measurement means very little.

TeaBagMania · 06-07-2015 3:50pm

Can’t you treat non-potable water with chlorine, should make it plenty safe for washing clothes and showering

Chemical Byrne · 06-07-2015 4:00pm

You shouldn't use the harvested water for your hot water requirements unless you've it treated to a fairly good degree. You must remember that all the bird sh!te and whatever other gunk off your roof will be dissolved in it and a lot of that isn't filterable.

Filtered raw rainwater is only good for outside use and for flushing toilets.

Even that considered, by the time you've factored in the cost of equipment, operation & maintenance and most importantly, your time, the extra little bit on the water bill will be looking fairly attractive.

Did a few quick calcs on this in college, for your average home the payback on the equipment capex was something like 6 years. That doesn't inlcude time spent fooling with it or, obviously, operation & maintenance costs. Basically, domestic RRW has no cost benefit, ergo, it's a waste of time and money.

Calahonda52 · 06-07-2015 4:20pm

Chemical Byrne wrote: »

Did a few quick calcs on this in college, for your average home the payback on the equipment capex was something like 6 years. That doesn't inlcude time spent fooling with it or, obviously, operation & maintenance costs. Basically, domestic RRW has no cost benefit, ergo, it's a waste of time and money.

Good to have the benefit of a college education, presumably at the taxpayers expense.

Did they teach you in college that projects that have 6 year paybacks are a waste of time and money?

Your simplistic approach ignores quite a bit:
just on the "time spent fooling"
How much time have u spent cleaning hardware gung off showers, toilets, taps, etc?
How much less soap is used with soft water?

How long more do dishwashers clothes washing machines etc last?

Chemical Byrne · 06-07-2015 4:26pm

Well as aI said that didn't even include all the costs so it's probably much longer in reality. By the time 5 or 6 years rolls around items like pumps, valves etc are probably starting to fail and be in need of replacement. - more time, more money more hassle.

We concluded that it just made more sense, from a money, time and convenience perspective , to meet all your water needs from the mains. It's different for large commercial operations that use a lot of water.

cerastes · 06-07-2015 4:33pm

Chemical Byrne wrote: »

You shouldn't use the harvested water for your hot water requirements unless you've it treated to a fairly good degree. You must remember that all the bird sh!te and whatever other gunk off your roof will be dissolved in it and a lot of that isn't filterable.

Filtered raw rainwater is only good for outside use and for flushing toilets.

Even that considered, by the time you've factored in the cost of equipment, operation & maintenance and most importantly, your time, the extra little bit on the water bill will be looking fairly attractive.

Did a few quick calcs on this in college, for your average home the payback on the equipment capex was something like 6 years. That doesn't inlcude time spent fooling with it or, obviously, operation & maintenance costs. Basically, domestic RRW has no cost benefit, ergo, it's a waste of time and money.

Personally I wouldnt use harvested water for anything other than flushing toilets/garden/washing car and for toilets only after Id strained and filtered it and possibly UV treatment, although maybe not RO.
Toilets I think is was where the biggest consumption and waste of a large volume of potable water is, I saw someone do a study on it in college myself, it was something like 2/3rds of all the water useage or maybe even greater.
That said, water is water and it can be filtered and cleaned like any water can for any purpose, whether or not it would be worthwhile to go to a potable standard in a domestic scenario or not is another thing, I think not.

But I disagree that it is not worthwhile or that its a waste of time and money to harvest to use in water the garden, washing the driveway/car and flushing the toilet, as vast quantities of potable water are wasted this way.
Despite the fairly large costs I see proposed to instal a rainwater harvesting system by private operators, a competent (or even an incompetent) DIYer could cheaply install a system to collect rainwater, I dont know why the Govt doesnt have a private funded body to come up with efficient free standardised designs but not solely along the lines of water harvesting to promote sustainability (ie pump sizes/components/wiring requirements for those less in the know) and let people get to work at it themselves as much as they are able.
They fund enough other quangos and shyite. This obviously falls foul of their own outlook and agenda, namely tax and vat revenue and of course any real view on actually conserving water, as the less you consume the less you will pay (for now).

The more people conserve and store water, the greater the buffer this provides for the existing system as people are taking less out, ie only to drink/cook and the less cost should need to be spent upgrading it to increase capacity.
Ive read it could even act as a means to prevent certain flooding/or at least reduce the strain on surface water drainage in times of lots of rain (Ive seen something like this mentioned regarding abandoned houses in the US and basements), while not as significant an issue here, if a means to prevent large voulmes of surface water otherwise wasted being dumped into drains and rivers and sometimes sewers where people can put it to use, but if a lot of people could store even a fraction of run off (which is greatly contributed to not being absorbed by soil due to large swathes of concreted/tarmaced/roofed surfaces) water especially in affected areas then it might have other advantages.

Ive yet to get around to doing it myself, as Ive a host of other jobs to do, but once any cost benefits run out, I see no harm in doing it, even if its only break even or barely, its a sustainability and management concern

What do you mean by RRW? I did a quick google to see was it an abbr or acronym for something but it turns up nowt.

Chemical Byrne · 06-07-2015 4:45pm

Sorry, I meant RRH.

I do a fair bit of work in relation to flood estimation etc. You would need an enormous level of RRH uptake to be able to attenuate flooding to any significant degree. It is possible in theory but in practice it just isn't a credible argument. Anyway, roofs only account for a small fraction of impervious urban surfaces.

I'd say you're right in saying toilets are a major user in most households. Reduced flush toilets would go a great distance to reducing consumption from them. Old toilets had a ridiculous flush volume or 9 litres or more. Modern dual flush toilets only use 4-6 litres so a significant reduction is possible in that alone.

cerastes · 07-07-2015 3:53am

I agree about the flood control really but it can be of no harm as a consideration, anybreuced volume of water getting into the drainage system can't be a bad thing, but more particularly because reduced demand on the potable supply by reducing the volume flushed in low flow and by using harvested water means less money has to be invested on upgrading capacity.
Although I think there should be a huge response to fixing leaks in the supply side, I also believe there should be good support to reduce the demand and for very little cost support retro fitting of lower flow equipment in older cisterns rather than outright replacement and also for rainwater harvesting.

Rain Water Harvesting

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