Rain Water Harvesting - where do I start?

[rana]

I have a rainwater harvesting system that comprises 3 linked water butts which collect water from my roof. The water is pumped through a hosepipe into a loft tank using a 12V caravan pump (about £20). The caravan pump has an old car battery as the power source which is charged using a roof mounted solar panel.
The water is used to flush the loo and supply to the washing machine. These are the household areas where most water is used. The installation costs of less than £100 have been far outweighed by the savings in metered water bills.

I am fortunate that the water butts are discretely placed to one side of the property.

[Kristen]

The installation costs of less than £100 have been far outweighed by the savings in metered water bills.

Is it fair to say, though, that that depends on the length of plumbing runs? - which in turn depends on the topography (is that the right word?) of the house, and whether Loos and Washing machine are in similar, or completely separate, areas?

All our pipes are buried in the walls, and we have two downstair's loos, which would require a lot of re-jigging to get a new water-supply pipe to them.

Hmmm ... I wonder how many loo-flushes we have a day. Maybe I'll put a pen & pad in each loo and ask people to mark each time they are used, and I could then guestimate what proportion of water used is loo-flushes - it may be more than I think, and maybe only one of the downstairs loos is used 90% of the time ...

Food for thought, thanks

[Potstubsdustbins]

With regards to loos many years ago the cisterns were 2 gallon approx 9 lts capacity. This was reduced to 7 ltrs by water authority by law and it as since been slightly reduced again to I think just over 6 ltrs. So it really depends on how old your loos are as to how much water you use.

The main problem is that the two main parts of a loo the cistern & basin are designed together. Therefore you cannot just stick a new 7 ltr cistern on an old basin as there is not enough water to flush solids correctly.

Dual flush are a great help providing that people only use the big flush when it is needed.

Kristen I think when you do the maths you are going to be suprised as to how much good fresh water goes down your loo.

Colin.

[lfnfan]

well, I did a few calcs based on met office historical rainfall data for my area, my roof 'footprint', and a general water utilisation figure off answers.com.

I learned a few things so far:

- SE England seems to get remarkably regular rainfall across the months. Although with a high degree of deviation from the mean (droughts I suppose)
- The water gathering capabilities of my roof are 2 to 3 cu.m/mth at 80% efficiency
- I really need some better utilisation figures than provided by answers.com. Will I really use 8 - 10 cu.m/mth between may and september?
- Veolia charge me £0.91 per cu.m for water plus £0.51 per cu.m for sewage (calculated on how much water I use) - £1.42 in total. Based on the general utilisation figure, taking all the garden water from the mains would cost me £96 annually.
- If i don't have an irrigation system, or use a hosepipe I can ask nicely and Veolia might Revert me back to unmetered.
- underground water tanks are blooming expensive.

[Kristen]

I think you can save an extra fiver a year if you start your "year" / spreadhseet on 1st November, rather than 1st January, as you will be able to carry forwards the 3,184 litres from December to January

"Will I really use 8 - 10 cu.m/mth between may and september?"

Is reading your meter once a month feasible? (Once a week would be better - you could save enough to buy a rainwater harvesting system if you detected an underground leak a week or two earlier ...)

[Potstubsdustbins]

If a leak was big enough to show on your water meter you would have something called a 'pond'. If at anytime you think you might have a leak you can do one of two things which cost nothing.

(a) Contact your water authority, they may take some time to get to you but it will be free in the first instance.
(b) Turn off everything in your property that uses water go to your water meter or external stop cock and using something metal connect your ear to the metal pipe and listen. You will be surprised how easy it is to hear a leak! You will see people from the water board doing this with a purpose made 'listening rod'.

Things to be aware off.

What everyone knows as the stopcock in the road/street is in fact correctly called a 'boundry box'. It forms the boundry between the water authorities responsibilty and yours. Yes that underground pipe between the boundry box and your home is your responsibility you pay for the repairs. Usually BIG time.

If you do call in the water people they can serve you with a notice to ensure you have any leak repaired.

As to free rainwater I am not sure where the boundries are but I do know that if you have a well in your garden the authorities can charge you to use 'their' water.

Colin

[rana]

As to free rainwater I am not sure where the boundries are but I do know that if you have a well in your garden the authorities can charge you to use 'their' water.

Colin

The water companies actively encourage water saving measures and frequently sell water butts and downpipe kits. I imagine any collected rainwater is 'yours' as are any installation costs incurred.