Using old oil tank for rain water harvesting?

Tony, I've done something similar to what you are planning with 4 linked 1000 litre IBCs, gutter diverters and a WVO filter bag on the inlet to the IBC. The pump is a £50 boat/motorhome 12v diaphram pump with auto pressure switch. I also have a 1 micron in line filter with the pump, and use a basic ozone generator to bubble through the tank and hopefully keep the water relatively fresh.

I use the water in the toilets, washing machine and in the garden for watering the plants, and sometimes in the pressure washer. I am using approx 3000 litres per month from it (2 people in the house) so approx £10 saving per month. Payback period for the basic toilet flushing system was 1 to 2 years. Adding the filters and ozonator pushed it out another year, but meant I was happier to use the water in the washing machine. I was lucky and got the IBCs for free, although the going rate is about £25.

The water is pumped directly to the toilet cisterns and washing machine, with extra pipes, not to a header tank. There is an airgap between the rainwater and mains, in that if I want to switch the toilets back to mains, I just unplug the speedfit flexi connector from the pipe on the cistern and and connect it back to the capped off mains pipe. This takes about 2 minutes, and I need to keep this capability for when the system freezes in winter!

It also avoids any possibility of cross contamination with the mains, without the complexity of creating a header tank and weir arrangement.

PM me if you want a link to some pics.
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. I am using approx 3000 litres per month from it (2 people in the house) so approx £10 saving per month.

are you sure off your figures ???

i pay £160 a ton/cubic metre/1000L so unless your getting the disposal rebate it going to be nearer £5 off course your water may be more expensive :D :D
We're with Wessex water. I don't have the bill handy, but I believe it worked out at just over £3.50 combined supply and sewerage for 1000L, with supply and sewerage costs about half each. Sewerage is worked out at 95% volume of supply.
your lucky then i wished my water was that expensive then my frugal efforts would be better rewarded :oops: :eek:

a breakdown off my bill 28cubic m a year =£45 standing charges £75
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I went to an opening party at a friends house tonight.

He has fitted 6000 litres of rainwater storage in the basement! As there were 40 people there he did not have time to talk much about it but I will be interested to hear his calculations another day.

I dont see that he is going to get too much rainwater from his roof as my assessment would be about 40,000 li per annum. Thats less than seven refills!

The rainwater is only being used to flush his seven toilets!

the obviouse savings come from grey water storage from sinks/baths and washing machines then recycled to toilets cisterns to get the maximum recycle rate
He has not taken the boiler condensate to the tanks though!

The house is only about 17 kW heat loss but he has quite a powerful boiler because of the pool heating.

He has fitted two 500 li thermal stores, one for hot water and UFH and the other for the pool. The hot water one has a 100 kW plate HE.

I have not yet worked out why he thinks he needs a thermal store for the pool. The more I think about it the more I think he does not need one!

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