I want to put in rainwater harvesting into a new build house, but there are a couple of issues:
1. it's a small roof in London - 70m2. I think it rains about 600mm per year in London - so, if I've got it right it will deliver about 70 * 0.6 * 0.7 (70% efficiency) * 1000 = 2940 Litres
Not a huge amount of water - but every little helps, and it should be able to do low flush WC's and maybe the washing machine?
Here are my questions:
In order to get the water to the tank I think I will have to bury the tank (space and aesthetics). I think that a 1500L tank will be ample - but I can't seem to find a 1500L tank that works with a direct system - due to space and pipe run limitations I'm not sure that a header tank would work.
All of the companies that I have spoken to seem to offer the same thing - ie 3000L tanks - which would have implications for extra costs in digging more ground out foundation issues etc.
Anyone found any company that doesn't sell the standard systems?
Anyone not used a company and done it themselves???
Recommend you pop into your local boat chandlers as 1500 litres is a typical size.In addition you can install 12V pumps for PV/battery for the low carbon solution.
Regards
If you have any problems contact me.
We would do a 1500l tank with all the holes / fittings tailored to your set up for around the £400 mark.
I live in a standard 50's semi, with a garage on the side. All the guttering leads to a 1500 litre tank. When it rains, it fills at up to 4 litres/minute ( I measured with a bucket ). The whole tank was filled in the last downpours ( a couple of days ) to overflowing ( I forgot to add an overflow ).
I think you have underestimated how much water you will collect. We use ours for the toilet and the washing machine, and have an extra tap in the kitchen - we use rain water for rinsing the sink, filling pans that need soaking, washing the floor etc.
gus
posted on 31-10-06
Thanks both of you for your help with the tank.
what about the other bits: i.e the control panel, the filters the pump etc. - would I be better off buying these separately or as a package?
I'm a little nervous about trying to fit them all myself and would rather find someone to supply and install.
What do you think? Am I being over-cautious? Is it more straight forward than it sounds?
Cheers
gus
posted on 31-10-06
John,
I didn't point out that this is a 70m2 flat roof - which is pretty small for a roof. If you take a standard semi - at a guess your roof is pitched and therefore probably 60-70 m2 each side - ie twice the size that I will get. I got the figures checked out by a company as well.
The only thing is that I have heard that weather conditions are changing and that we are getting heavier downpours that we used to.
Not sure whether average rainfall is going up or down? We hear a lot about average temps - but not much about rain - although we have drought conditions - that's partly to do with 'not enough drizzle' - which apparently feeds into the acquifiers quicker?
Please correct me if I'm wrong - this is all stuff I've picked up - and I'm no expert!
