Dual plumbing for future rainwater harvesting

sparks3000

As title says , what pipe work should I see for this . Thanks in advance

Walter Becket

Are you building a new house?

Walter Becket

If so you need the down pipes taking the rainwater to bring it to wherever you plan to put the reception tank this is a huge concrete tank under the ground. When installed the water should be able go from this tank to a soakaway when the tank is full
So I'd say put your soakaway far enough away that there is space to put in a rainwater storage tank later.

Pete67

Assuming a new build, if you plan to make use of rainwater in future I would recommend installation of a secondary cold water cistern in the attic for future rainwater use, and pipe from this to supply all toilets, the washing machine, an outside tap and nothing else. Showers and sinks should be supplied via the primary mains fed cistern. Initially supply the second cistern from the rising main, and at a later date it would be straightforward to switch it over to the underground rainwater storage tank. You would need to pump the water up to the attic via a suitable filter to remove debris. You should also install a second 1/2 inch rising main from the location of the underground rainwater storage tank to the attic, ideally in 1 continuous length of heavy duty hydrodare pipe.

sparks3000

Thanks for the replies I have just finished a new build myself but my question relates to my friend who is hoping to be finished a new build in the next few months. He was showing me his construction spec when I saw allow dual plumbing for future rainwater harvesting. I could not see any extra pipes for this so was just curious as to what should have been installed

North West

Hi. Dual plumbing means; A rainwater system and a mains system working side by side. The rainwater being one system and the mains as a system. Two seperate identities. The rainwater being put in for Toilets/ Washing machine/outside taps only. Mains water for potable water feeding taps/showers etc. For your rainwater system you need to do a bit of homework, what you need. 1. Your Average Rainfall Yield for the year 2. Your Average Rainfall Demand per year 3. The floor area of your home in sq mtrs 4. The above will allow you to size your Rainwater Tank. You can use a direct pressure system or a gravity feed system. Direct pressure system allows you to feed your toilets/washing machine direct from your rainwater tank by means of a pump system. Gravity feed system is by pumping thewater from your rainwater tank to a seperate rainwater tank in the attic and gravity feed pipe work to toilets etc. If you are setting up to do a system make sure you downpipes go directly to rainwater take and not down through gullies then too tank. Which ever system you use, you back up the system with mains water, so you are never without water. Something worth reading: Google BS8515;2009, this is the standard the rainwater system is goverened by. Good information. The best system is an under ground tank system. Your rainwater system can save you around 45% of your mains water bill over the year. The initial system cost will through time pay for itself and you will have free rainwater for life. NW

Walter Becket

North West wrote: »

Hi. Dual plumbing means; A rainwater system and a mains system working side by side. The rainwater being one system and the mains as a system. Two seperate identities. The rainwater being put in for Toilets/ Washing machine/outside taps only. Mains water for potable water feeding taps/showers etc. For your rainwater system you need to do a bit of homework, what you need. 1. Your Average Rainfall Yield for the year 2. Your Average Rainfall Demand per year 3. The floor area of your home in sq mtrs 4. The above will allow you to size your Rainwater Tank. You can use a direct pressure system or a gravity feed system. Direct pressure system allows you to feed your toilets/washing machine direct from your rainwater tank by means of a pump system. Gravity feed system is by pumping thewater from your rainwater tank to a seperate rainwater tank in the attic and gravity feed pipe work to toilets etc. If you are setting up to do a system make sure you downpipes go directly to rainwater take and not down through gullies then too tank. Which ever system you use, you back up the system with mains water, so you are never without water. Something worth reading: Google BS8515;2009, this is the standard the rainwater system is goverened by. Good information. The best system is an under ground tank system. Your rainwater system can save you around 45% of your mains water bill over the year. The initial system cost will through time pay for itself and you will have free rainwater for life. NW

I agree with all you say NW except the last sentence. Water is never free the pump has a life of 10 to 15 years and will usually need maintenance in that time, the filters need annual maintenance or more often. Rainwater is acidic it will rot copper, brass and iron. Not all parts are available in plastic or stainless steel as far as I know.
The owner will have to live a long life for the system to pay for itself at current water charge prices
Fitting the pipe work to allow a system to be put in in future incase the water charges go up dramatically makes sense.

North West

Walter Becket wrote: »

I agree with all you say NW except the last sentence. Water is never free the pump has a life of 10 to 15 years and will usually need maintenance in that time, the filters need annual maintenance or more often. Rainwater is acidic it will rot copper, brass and iron. Not all parts are available in plastic or stainless steel as far as I know.
The owner will have to live a long life for the system to pay for itself at current water charge prices
Fitting the pipe work to allow a system to be put in in future incase the water charges go up dramatically makes sense.

Hi Walter
The rain is free, but the system is a cost and the maintenance of parts is reasonable over the years. Like buying a car you need the essentials over the year, tyres service etc. The pipe work can be put in for future installation. The need to properly size the system and all it's components is essential before any pipe work is done. Otherwise a mistake could be costly. The tank needs to be sized whether over ground or under ground. The pump needs to be sized properly to give you adequate flow rates. The pipe work will be sized according to the flow demand for the property. You have to decide whether system is direct pressure or gravity feed from header tank. All these things and more need to be decided before you do anything with pipe work. I would recommend a proper survey on the property before anything is done, this would take approx 3 hours. The survey enables you to put everything together from specification to pricing and options available for the particular property.
NW

cerastes

What kind of pump would be suitable for this?
Would a pump need to be a negative head type which would be costly? Is if the tank is at or under ground level?