gravity fed rainwater header tank - how would you do it?

slipstream

Hi,

I am about to start a retrofit of our bungalow in Dublin.

The renovation will include adding a 25 square meter flat dormer roof and I hope to direct the drains here into a storage tank in the attic which will in turn feed the 1 upstairs and 2 downstairs toilet cisterns. The drop from flat roof drain to rainwater tank would only be between 5m and 1m.

I was thinking that this might work roughly as follows -
1) roof inlet with self cleaning leaf filter to keep wind stuff out
2) inlet pipe goes into attic into a sediment filter and/or first flush diverter with outlet to drain (inside to enable filter cleaning)
3) filter or diverter outlet goes into tank and drops down to underwater outlet (to act as water trap)
4) 400+ liter tank with lid
5) mechanical mains top up valve to ensure tank never empties
6) overflow with water trap to rainwater drain
7) second overflow with water trap to outside (double overflow as precaution since overflow will be frequently used)
8) outlet connected to all toilet cisterns

However, I don't have any experience whatsoever and so have no idea if this setup would work or be problematic. Also, I cannot find many resources online about this type of setup.

Some of the challenges I foresee are -
a) ensuring the systems does not overflow at anytime!
b) ensuring inlet pipework doesn't get blocked with crud
c) ensuring that the system can cope in a downpour
d) reducing the amount of filter maintenance
e) ensuring sufficient drop from tank to upstairs toilet cistern
f) avoiding severe sediment buildup at the bottom of the tank

Have any of you guys setup a similar systems or do you have any tips on how you would do it?

Thanks for your help,

Slip

North West

Hi slipstream
Can you put up rough sketch of what you are hoping to do ?.
NW

shane ryan 2013

Contact a professional what your trying to do is not for a diy enthuse .

lgk

shane ryan 2013 wrote: »

Contact a professional what your trying to do is not for a diy enthuse .

Depends to what level the OP wants to use the harvested water, and their DIY skills, but it's not really all that complicated. Plenty of DIY kits available from basic solutions to the more complex with whole house filtration. The plumbing in most cases is pretty low level.

OP, I think the greatest challenge in your plan will be gravity! From the flat roof, you're going to need a tank at or below ground level. Downspout filter to remove the worst of the debris, then further, serviceable filtration before the tank. You'll need a submerged pump to take the water from here up to the attic tank.

slipstream

lgk wrote: »

Depends to what level the OP wants to use the harvested water, and their DIY skills, but it's not really all that complicated. Plenty of DIY kits available from basic solutions to the more complex with whole house filtration. The plumbing in most cases is pretty low level.

OP, I think the greatest challenge in your plan will be gravity! From the flat roof, you're going to need a tank at or below ground level. Downspout filter to remove the worst of the debris, then further, serviceable filtration before the tank. You'll need a submerged pump to take the water from here up to the attic tank.

To be honest; the greatest challenge was my stupidity as I only recently noticed that with a 25 square meter collection area, only 17+ cubic meters of water could possibly be collected every year (25 x .7m annual rainfall in Dublin) and that is way too low to service all of our toilet and washing machine needs!

I think the design is perfectly feasible for someone with a larger roof area though. The tank would sit between the gutter and highest toilet cistern in a cabinet so that no pump would be needed. Inflow would come from a leaf filter and 2 overflows back out to be safe. water traps on all pipes to keep cold air out. mechanical mains top up valve in case the tank runs low.

Slip

lgk

slipstream wrote: »

The tank would sit between the gutter and highest toilet cistern in a cabinet so that no pump would be needed.

That's probably a bigger cabinet space than most people would be willing to forfeit within the house though.

slipstream

lgk wrote: »

That's probably a bigger cabinet space than most people would be willing to forfeit within the house though.

probably but if it reduces their water bill by 30 - 40% then some people might consider it.

slip

Leaksireland

Our house at home has an underground tank in the front lawn. It was built in the early 70's. All the water from the gutters goes through a gravel filtration system and then into the tank. Its then pumped from the underground tank back into the attic tank. This feeds everything except the drinking water.
Its years since i was down there but id say it could hold around 15-20 cubes of water.
To maintain it we only cleaned the gutters twice a year and changed the gravel in the pit every five years.
Maybe i wasnt the most healthy system but never had any damage done to any appliances in the house.

kryan1

Leaksireland wrote: »

Our house at home has an underground tank in the front lawn. It was built in the early 70's. All the water from the gutters goes through a gravel filtration system and then into the tank. Its then pumped from the underground tank back into the attic tank. This feeds everything except the drinking water.
Its years since i was down there but id say it could hold around 15-20 cubes of water.
To maintain it we only cleaned the gutters twice a year and changed the gravel in the pit every five years.
Maybe i wasnt the most healthy system but never had any damage done to any appliances in the house.

Hi there, can u give me an idea of the gravel filter system u have, I am putting in a tank and I wanted some filter system before it goes into the tank and this sounds perfect.

Leaksireland

kryan1 wrote: »

Hi there, can u give me an idea of the gravel filter system u have, I am putting in a tank and I wanted some filter system before it goes into the tank and this sounds perfect.

The system in our house is in from the early seventies, so i'd say its outdated.
I had a quick look on google and there are plenty of examples of different systems that you can use. I'd recommend researching there for what best suits you.