Harvesting Rainwater

yellatdave

As I understand it, our attic tanks provide water to the toilets/showers/washing machine/bathroom taps, etc. None of this tank water is drinkable.
But water from our kitchen taps, which are fed straight from the mains, is drinkable.

If I wanted to change the bathroom tap feed to take drinkable water straight from the rising main (like the kitchen tap) instead of the attic tank, would this be a big job?

Has anyone got this done?

loyatemu

why?

the attic tank is fed from the mains, presumably a competent plumber could take a feed off that to your bathroom tap. Might be issues with pressure though.

yellatdave

Final goal is to take all this lovely rainwater we're getting & have a system for pumping it to the attic tank to serve everything in the house except the taps. Don't think having unfiltered stored rainwater would be hygienic enough for teeth-brushing, so I want these to be mains-fed.

Since I know very little about plumbing, wanted to know if the feed for the bathroom taps can instead be taken from the rising main in a neat (& cheap) manner. Good point on pressure by the way. Hadn't thought of that, but don't think it would bother me.

2011

yellatdave wrote: »

Final goal is to take all this lovely rainwater we're getting & have a system for pumping it to the attic tank to serve everything in the house except the taps.

Unfortunately untreated/filtered rain water is good for watering the garden and little else.

Algae in the rain water will cause it to turn yellow with a green slime forming surface quite rapidly.

This may interest you:

http://rainwaterharvestingsystemsireland.town.ie/

Jimjay

Would you want to bath and shower in rainwater?

pixbyjohn

Jimjay wrote: »

Would you want to bath and shower in rainwater?

Its great for the complexion

FirstIn

pixbyjohn wrote: »

Its great for the complexion

I agree. Remember that girl in the Timotei add. Her hair looked great and she was washing in a stream.

I'd say go for it. You'll be the better for it.

yellatdave

After my little bit of research today, discovered that unfiltered rainwater (minus the major debris) can be used for the garden, toilets & washing machine. If I add a 2-filter system, (5-10 micron filter & carbon filter), I should be able to use it for the showers/bath too.

The cost of the extra filters could be offset by avoiding the cost of replumbing (so I can still feed the rainwater straight to the attic tank).
I'll have the shampoo bottle at the ready!!

2011

Why?

I don't think this would be very good for your washing machine.
Toilets unlikely to look very clean too

Dtp1979

Rain water will look clean. My biggest concern is the acidic level. Would you bath a young child in water that might be slightly acidic??

Annasopra

My granny used to wash her hair with rainwater all the time - never did her any harm

2011

Reasons that water harvesting is not popular in Dublin according to Dublin County Council include:

• The relatively high cost of the systems especially if retro-fitting.
• Concerns that the quality of the water may pose a health risk.
• Requires some technical skills to install and provide regular maintenance.

They go on to say:

For existing premises it is generally more economic to reduce water use by fitting more water efficient appliances and changing habits and behaviours before considering the use of complex rainwater harvesting systems. It is important to evaluate the potential savings before investing in a rainwater harvesting system.

Link:
http://www.dublincity.ie/WATERWASTEENVIRONMENT/DRINKINGWATER/RAINWATERHARVESTING/Pages/RainwaterharvestingFurtherInformation.aspx

yellatdave

The following 2009 study claimed that rainwater was safe to drink.

http://www.sciencedaily.com/releases/2009/11/091104091728.htm

While it makes for interesting reading, I would still be very hesitant to drink it.

For my purposes, a 5-micron filter + carbon filter should remove any unpleasant colours/odours & particles that could trouble a toilet/washing machine (sediment bigger than 50 microns can interfere with toilet mechanisms).

As for acidity, rainwater is almost 100% pure before it reaches the ground. If the storage tank & piping are certified for potable water use, and I put in the two filters, can't see a problem using it for everywhere except kitchen.

Dtp1979

yellatdave wrote: »

The following 2009 study claimed that rainwater was safe to drink.

http://www.sciencedaily.com/releases/2009/11/091104091728.htm

While it makes for interesting reading, I would still be very hesitant to drink it.

For my purposes, a 5-micron filter + carbon filter should remove any unpleasant colours/odours & particles that could trouble a toilet/washing machine (sediment bigger than 50 microns can interfere with toilet mechanisms).

As for acidity, rainwater is almost 100% pure before it reaches the ground. If the storage tank & piping are certified for potable water use, and I put in the two filters, can't see a problem using it for everywhere except kitchen.

Any scientific evidence to support your last paragraph?? I'm not being smart. I was all set to install my own system until I heard about the acidity issue. If there was evidence to support your claim I'd be delighted.

yellatdave

Dtp1979 wrote: »

Any scientific evidence to support your last paragraph?? I'm not being smart. I was all set to install my own system until I heard about the acidity issue. If there was evidence to support your claim I'd be delighted.

I'm open to correction, but I got a lot of info from the site below, and if the Australian study says its safe to drink, it stands to reason that it can't be too acidic to shower/bath in.

http://www.whollyh2o.org/rainwater-stormwater/item/122-rainwater-quality-and-filtration.html

drag0n79

yellatdave wrote: »

I'm open to correction, but I got a lot of info from the site below, and if the Australian study says its safe to drink, it stands to reason that it can't be too acidic to shower/bath in.

http://www.whollyh2o.org/rainwater-stormwater/item/122-rainwater-quality-and-filtration.html

While I'm all for water conservation, I'd still have problems with showering in rainwater that has come off a dirty roof and picked up bird droppings and insects and whatever else along the way. Even if it was filtered afterwards. Do you not also need an ultraviolet filter?

A lot of the 'drinkable rainwater' studies were done with rainwater collected from carefully cleaned surfaces.

If you do go ahead with it make sure your tank overflow works properly and that you have some way to divert the incoming rain back down the normal drainpipes in case of emergency (i.e. rainwater coming through the ceiling from a leaky pipe or overflow not emptying quickly enough). For the mains at least you have the mains stopcock for emergencies.

Dtp1979

drag0n79 wrote: »

While I'm all for water conservation, I'd still have problems with showering in rainwater that has come off a dirty roof and picked up bird droppings and insects and whatever else along the way. Even if it was filtered afterwards. Do you not also need an ultraviolet filter?

A lot of the 'drinkable rainwater' studies were done with rainwater collected from carefully cleaned surfaces.

If you do go ahead with it make sure your tank overflow works properly and that you have some way to divert the incoming rain back down the normal drainpipes in case of emergency (i.e. rainwater coming through the ceiling from a leaky pipe or overflow not emptying quickly enough). For the mains at least you have the mains stopcock for emergencies.

Oh a UV filter is a must

drag0n79

Dtp1979 wrote: »

Oh a UV filter is a must

Definitely, to disinfect the water. OP only mentioned 5-10 micron filter & carbon filter.

2011

An interesting project, but the question to the OP still remains:
Why are you doing this?
From a financial point of view it makes no sense.
Installation will be costly as it is a retro fit. Maintenance and running costs will not be free either.
Form an environmental perspective manufacturing the materials will have a large carbon footprint, which I would think would outweigh the environmental impact due to your reduced water demand for Wicklow County Council.
As per the link from Dublin County Council if the enviroment is your primary concern you may be better off looking at using appliances that consume less water.

dathi

drag0n79 wrote: »

While I'm all for water conservation, I'd still have problems with showering in rainwater that has come off a dirty roof and picked up bird droppings and insects and whatever else along the way. Even if it was filtered afterwards. Do you not also need an ultraviolet filter?A.

as apposed to using the water supplied by your council ? EPA report "the provision and quality of drinking water 2011" says 1.3% of public supplies 10% of group water schemes and 7.4% of private wells tested had ecoli present

2011

dathi wrote: »

as apposed to using the water supplied by your council ? EPA report "the provision and quality of drinking water 2011" says 1.3% of public supplies 10% of group water schemes and 7.4% of private wells tested had ecoli present

....but it would be far cleaner than rain water and perfect for toilets, showers, washing machines etc.

dathi

how would it be cleaner if you are one of the unlucky 10% that has e.coli supplied to them in their drinking water? the op said that he was going to filter the rainwater so that would remove any dirt from the water. if he puts a uv filter on it as well it would kill any bacteria leaving it cleaner than the above 10% and if you are worried about the acidity of the water(cant see why) you can buffer it by putting crushed oyster shells in the tank.

K.Flyer

The pipe work involved in retro fitting in a water harvesting system in a urban situation could be quite expensive and the costing for one particular house is not something you can go by unless both are exactly the same i.e. neighbours.
To be honest and if you think about it for a minute, careful usage and conservation should save you a lot more money than you would spend on a full on system complete with proper filtration and uv, not to mention the annual running cost.
Unless you are one for watering the lawn, washing the car and power washing around your house on a regular basis I really cannot see the savings vs the set up costs, unless someone has ALL the figures worked out.

yellatdave

2011 wrote: »

An interesting project, but the question to the OP still remains:
Why are you doing this?
From a financial point of view it makes no sense.
Installation will be costly as it is a retro fit. Maintenance and running costs will not be free either.
Form an environmental perspective manufacturing the materials will have a large carbon footprint, which I would think would outweigh the environmental impact due to your reduced water demand for Wicklow County Council.
As per the link from Dublin County Council if the enviroment is your primary concern you may be better off looking at using appliances that consume less water.

Various reasons, depending on my final use (which I'm still mulling over).

Financial: concur there is a large upfront cost (principally the cost of tanks). The payback period may take years, (depending on how much 'Irish Water' decide to fleece us annually). Then again, payback may not happen at all, but I figure set-up costs/maintenance would be negligible vis-a-vis water charges over the long-term.

Self-sufficiency: like the idea of this. When I consider last year's water cut-offs, or potential summertime hose-pipe bans, watering my veg garden or washing my car guilt-free sounds good. Flushing the toilets, wash the clothes, having a shower, etc., despite water cut-offs, even better!

Health: if I went the full-hog & added a UV light to make the rainwater drinkable, I could use it for 100% of my needs. No more fluoride, chlorine & aluminium mains-fed water for me... yipee!

2011

Best of luck with it.

Jimjay

yellatdave wrote: »

Various reasons, depending on my final use (which I'm still mulling over).



Self-sufficiency: like the idea of this. When I consider last year's water cut-offs, or potential summertime hose-pipe bans, watering my veg garden or washing my car guilt-free sounds good. Flushing the toilets, wash the clothes, having a shower, etc., despite water cut-offs, even better!

So if there is a drought or lack of rain where will you get your guilt free water from for tour veg or car in addition to baths, showers, washing up etc.
You must be planning one big storage tank. ;-)

Dtp1979

Jimjay wrote: »

So if there is a drought or lack of rain where will you get your guilt free water from for tour veg or car in addition to baths, showers, washing up etc.
You must be planning one big storage tank. ;-)

Obviously there would be a mains back up. He's on about using rainwater for the majority of the time.

yellatdave

Jimjay wrote: »

So if there is a drought or lack of rain where will you get your guilt free water from for tour veg or car in addition to baths, showers, washing up etc.
You must be planning one big storage tank. ;-)

Dtp1979 wrote: »

Obviously there would be a mains back up. He's on about using rainwater for the majority of the time.

Exactly. Will have a control box giving priority to rainwater feed, but once that empties, mains water feed kicks back in automatically. Haven't calculated storage capacity needed yet.

Dtp1979

yellatdave wrote: »

Exactly. Will have a control box giving priority to rainwater feed, but once that empties, mains water feed kicks back in automatically. Haven't calculated storage capacity needed yet.

I myself have only got space for 2 IBC tanks which is 2000 litres. Better than nothing I guess

Dtp1979

drag0n79 wrote: »

The OP is planning on storing rainwater in his attic. I doubt his ceiling joists would be too happy with 2 tons sitting on them. And how do you get an IBC tank into your attic?

It's all interesting to think about but as has been said above, just completely infeasible post-build, cost and work-wise.

Well I'm a plumber and have access to cheap materials and free labour obviously. I'd imagine the OP is doing the same as myself and collecting the rainwater outside and pumping it to the attic

2011

Dtp1979 wrote: »

Obviously there would be a mains back up. He's on about using rainwater for the majority of the time.

This will mean that you will have to pay the (knowing this country over inflated) water meter standing charge.

I'd imagine the OP is doing the same as myself and collecting the rainwater outside and pumping it to the attic

So you will need:
1) Tank(s) outside
2) Tank(s) in the attic
3) Buy, run and maintain a pump
4) Buy, run and maintain filtration system.

I myself have only got space for 2 IBC tanks which is 2000 litres.

All this so that you can store about €4 of water?

(Based on the cost to a business at present by Dublin County Council).
Link

Somehow I don't think that this will catch on

2011

By the way 2 cubic meters of water weighs 2 metric tons!
This extra weight will be spread across a few joists. Better check that they can take the additional load :eek:

Dtp1979

2011 wrote: »

By the way 2 cubic meters of water weighs 2 metric tons!
This extra weight will be spread across a few joists. Better check that they can take the additional load :eek:

I'm not putting 2 cubic metres in the attic. I'm using my existing attic tanks, putting the 2 IBC outside and pumping up to the attic. 2000 litres of water is alot of showers and flushing toilets

2011

Dtp1979 wrote: »

I'm not putting 2 cubic metres in the attic. I'm using my existing attic tanks, putting the 2 IBC outside and pumping up to the attic. 2000 litres of water is alot of showers and flushing toilets

Fair enough.
Where will you locate the pump and filtration equipment?

Dtp1979

2011 wrote: »

Fair enough.
Where will you locate the pump and filtration equipment?

Beside the tanks outside. They will be insulated and weatherproofed in one unit

yellatdave

2011 wrote: »

This will mean that you will have to pay the (knowing this country over inflated) water meter standing charge.



So you will need:
1) Tank(s) outside
2) Tank(s) in the attic
3) Buy, run and maintain a pump
4) Buy, run and maintain filtration system.



All this so that you can store about €4 of water???

Somehow I don't think that this will catch on

2000 litres = 1 cubic meter
Dublin County Council seem to be suggesting that a cubic meter of water will cost in the region of €2

Link:
http://www.dublincity.ie/Business/WaterCharges/pages/waterchargescalculate.aspx

2000 litres = 2 cubic metres, but based on the above cost, I'm coming in at €438 annually for a 4-person household:

Usage of approx 150 litres per person per day (source: http://www.waterwise.org.uk) for a 4-person household is 219,000lt per year, or 219 cubic metres @ €2 per cubic metre

While the €2 per cubic metre quoted is a business rate, it's broadly in line with UK domestic rates (Anglian water charge €1.80 approx per cubic metre), so probably pretty close to what its going to be.

Reckon I need:
1 x Pre-Tank Filter (€25)
2 x 1089lt potable water tanks (€1000)
1 x submersible pump with float switch (€150)
1 x MDPE 10mt flexible pipe (€25)
1 x 2-filter system (€165)
1 x control box (€40)

Rough costs:
Initial Set-up = €1,405
Annual running cost (filter cartridge replacements & electricity) = €65

Based on above, payback period in less than 3.5 years for 100% rainwater use. Reckon I'll be using 70% rainwater, thereby giving a payback period of roughly 5 years (if my maths are right!!)

yellatdave

2011 wrote: »

Fair enough.
Where will you locate the pump and filtration equipment?

Dtp1979 wrote: »

Beside the tanks outside. They will be insulated and weatherproofed in one unit

Very similar set-up, but with submersible pump. Float switch will cut off rainwater-feed when tanks are low & control box will then switch to mains-fed.

Would love to use IBC's like Dtp1979 to really cut down cost, but unfortunately need long narrow tanks to fit in limited space.

2011

Dtp1979 wrote: »

Beside the tanks outside. They will be insulated and weatherproofed in one unit

So the plan is:

1) Rain will fill the outside tanks.

2) This water will be pumped from the outside tanks to the attic tanks with an electric pump.

3) There will be some sort of inline filtration system between both tank systems (located outside).

4) If the outside tanks run dry due to lack of rain or otherwise the mains water will be used to top up the attic tanks.

5) There will be some form of level control on the outside tanks to ensure that the transfer pump does not dry run. This could be achieved easily & cheaply with a float switch.

Is that roughly the plan?
Please correct me if I am wrong.

Does the pump go upstream or down stream of the filtration system?
Have you a filtration system or pump in mind?
Do you intend on producing potable water?

2011

yellatdave wrote: »

2000 litres = 2 cubic metres, but based on the above cost, I'm coming in at €438 annually for a 4-person household:

Usage of approx 150 litres per person per day (source: http://www.waterwise.org.uk) for a 4-person household is 219,000lt per year, or 219 cubic metres @ €2 per cubic metre

While the €2 per cubic metre quoted is a business rate, it's broadly in line with UK domestic rates (Anglian water charge €1.80 approx per cubic metre), so probably pretty close to what its going to be.

Reckon I need:
1 x Pre-Tank Filter (€25)
2 x 1089lt potable water tanks (€1000)
1 x submersible pump with float switch (€150)
1 x MDPE 10mt flexible pipe (€25)
1 x 2-filter system (€165)
1 x control box (€40)

Rough costs:
Initial Set-up = €1,405
Annual running cost (filter cartridge replacements & electricity) = €65

Based on above, payback period in less than 3.5 years for 100% rainwater use. Reckon I'll be using 70% rainwater, thereby giving a payback period of roughly 5 years (if my maths are right!!)

You will need to consider:

1) Installation charge

2) The cost for pumping 219 metric tons of water from your garden to your attic (5m) per year? Is see that you have only allowed €65 for this including replacement filters. Seems a little low to me, have you done a calculation to back this up?

3) Maintenance costs. See above.

4) Sometimes it simply does not rain. Your calculation assumes that you will always have enough rain water.

5) What size is your roof area? Do you plan to collect all of the rain water from all of your roof? i.e. front & back of your home. Do you think you have enough roof area that you can collect 219,000 per year?

6) Do you have a 4 person household and therefore feel that you would consume the average amount of water for a 4 person household? I ask this because that is what this calculation is based on.

yellatdave

2011 wrote: »

So the plan is:

1) Rain will fill the outside tanks.

2) This water will be pumped from the outside tanks to the attic tanks with an electric pump.

3) There will be some sort of inline filtration system between both tank systems (located outside).

4) If the outside tanks run dry due to lack of rain or otherwise the mains water will be used to top up the attic tanks.

5) There will be some form of level control on the outside tanks to ensure that the transfer pump does not dry run. This could be achieved easily & cheaply with a float switch.

Is that roughly the plan?
Please correct me if I am wrong.

Does the pump go upstream or down stream of the filtration system?
Have you a filtration system or pump in mind?
Do you intend on producing potable water?

That's pretty much it. But step 1 will have a pre-tank filter on the downpipe, so no major debris enters the tank to trouble the pump.

Costs of filtration system & pumps were based on quick search of readily-available ones found on ebay/B&Q sites, but haven't settled on any particular one yet.

Still haven't decided on producing potable water. UV systems are pricy, but then again I'd be able to use 100% rainwater.

yellatdave

2011 wrote: »

You will need to consider:

1) Installation charge

2) The cost for pumping 219 metric tons of water from your garden to your attic (5m) per year? Is see that you have only allowed €65 for this including replacement filters. Seems a little low to me, have you done a calculation to back this up?

3) Maintenance costs. See above.

4) Sometimes it simply does not rain. Your calculation assumes that you will always have enough rain water.

5) What size is your roof area? Do you plan to collect all of the rain water from all of your roof? i.e. front & back of your home. Do you think you have enough roof area that you can collect 219,000 per year?

6) Do you have a 4 person household and therefore feel that you would consume the average amount of water for a 4 person household? I ask this because that is what this calculation is based on.

(1) Lucky to have an electrician uncle to give me a hand (who set up a similar system years ago).

(2) Replacement filters once a year @ €30. You're right, electricity was a bit low. Based on a 250watt pump running 3 hours a day = €60 annually

(4) That's why I'll have large storage capacity & a mains water back-up.

(5) Hope so! Based on observations of a few hours to fill my 500lt water butt in heavy rain while only using part of the roof catchment area, shouldn't see it as a problem. Was thinking of blocking-off the top of the other downpipe (not used for the system) to increase flow to the tanks, but unsure what weight stress this may pose to the guttering.

(6) Yep, a 4-person household.

2011

OK, just for the crack I did a very, very rough calculation of the electrical running cost per annum (that ignores all sorts of losses).


Work done to lift 219,000 litres of water to a hight of 5m = 219,000 x 9.81 x 5 = 10,741,950 Joules

(ignoring all losses frictional etc..).

Using a submersible pump such as this SCP5000


Assuming an output of 200W (taking into account pump losses) it will take = 150 hours to pump 219,000 litres of water to a hight of 5m.

Running this 220W pump for 1 hour will consume 0.22 units of electricity.

Therfore running this pump non stop for 150 hours will use 33 units of electricity.

At say €0.17 per unit this equates to a total cost of €5.61

Far less than I expected to be honest. Perhaps I have missed something due to over indulging last night :)

This assumes that the pump is running constantly, stopping and starting a pump will mean that it will consuming more electricity.

2011

yellatdave wrote: »

(1) Lucky to have an electrician uncle to give me a hand (who set up a similar system years ago).

Interesting, I would love to see this.

You're right, electricity was a bit low. Based on a 250watt pump running 3 hours a day = €60 annually

Perhaps your electricity allowance is more accurate that I initially thought.

The pump shown in my link above will transfer up to 15,000 litres in 3 hours, on that basis I don't think your pump will need to run for very long (as my pump is a similar size to yours). Although you can expect this figure to reduce due to the 5m head.

Remember 219,000 litres per year is only 600 litres per day (on average).

yellatdave

Knew they were efficient, but not that good!
Good pumps, will definitely check out.

yellatdave

2011 wrote: »

Interesting, I would love to see this.

More than welcome when up & running.

2011

yellatdave wrote: »

Knew they were efficient, but not that good!
Good pumps, will definitely check out.

Please don't take my very rough calculation as gospel. In the mist of a hangover I just randomly knocked of 20W from the pump input and gave it as an output to make some allowance for losses

Dtp1979

yellatdave wrote: »

2000 litres = 2 cubic metres, but based on the above cost, I'm coming in at €438 annually for a 4-person household:

Usage of approx 150 litres per person per day (source: http://www.waterwise.org.uk) for a 4-person household is 219,000lt per year, or 219 cubic metres @ €2 per cubic metre

While the €2 per cubic metre quoted is a business rate, it's broadly in line with UK domestic rates (Anglian water charge €1.80 approx per cubic metre), so probably pretty close to what its going to be.

Reckon I need:
1 x Pre-Tank Filter (€25)
2 x 1089lt potable water tanks (€1000)
1 x submersible pump with float switch (€150)
1 x MDPE 10mt flexible pipe (€25)
1 x 2-filter system (€165)
1 x control box (€40)

Rough costs:
Initial Set-up = €1,405
Annual running cost (filter cartridge replacements & electricity) = €65

Based on above, payback period in less than 3.5 years for 100% rainwater use. Reckon I'll be using 70% rainwater, thereby giving a payback period of roughly 5 years (if my maths are right!!)

Would an IBC tank not do for the potable water?

yellatdave

IBC's would be ideal (& much cheaper), but unfortunately I don't have the space for them. My garden is long & narrow, so need something to fit snuggly along one wall.

Dtp1979

yellatdave wrote: »

IBC's would be ideal (& much cheaper), but unfortunately I don't have the space for them. My garden is long & narrow, so need something to fit snuggly along one wall.

That's a pity. 120 for 2 IBC tanks. Maybe you could consider burying the tanks?

yellatdave

Good idea! But having dug holes in my garden before, once down more than 2 feet it becomes extremely difficult. With IBC's more than a meter high, don't fancy the idea of digging a few holes that deep. Although nothing better than nearly €900 saving to get the shovel out! :rolleyes:

yellatdave

Dtp1979 wrote: »

Would an IBC tank not do for the potable water?

Forgot to mention 2011's point on algae growth. Algae need sunlight, so you'll have that problem if using clear/translucent tanks like IBC's. Paint the plastic a dark colour or cover the tanks with a blackout material to avoid.