Rainwater harvesting

gromituk

That first flush thing sounds interesting. At the moment all I've got in the way of filtration is some stainless steel scouring pads sitting on brass mesh in downpipe hoppers. They catch a fair amount but obviously not all of the muck.

beetlebum_2

After doing lots of googling on rainwater harvesting, I have started on my project.

So far I have got 2 water butts connected into the downpipe. I've started installing pipe to feed the upstairs toilet, fed from a small header tank in loft. I may extend it to feed the dishwasher and washing machine. The only problem with supplying rainwater to my washing machine is that it needs 1 bar and I won't have enough head for this. The dishwasher needs 0.5 bar, so should be able to achive this.

I thought I would tell people here about the rainwater filter that hooks into the downpipe. It's called the 3P Rainwater Filter/Diverter. The cheapest price I have seen it for is £33.59 including delivery from Earth Systems. Basically, it has a mesh filter to remove all the crud from the tiles and gutters. I am very impressed with this device.

Last week I bought a submersible pump with float switch from Lidl for £24.99 which will be used to pump the collected water up into the loft to the header tank. To do this, the cheapest form of pipe seems to be 21.5mm overflow pipe (about £10 for 10x3M lengths). Using 22mm pipe, be it copper or plastic is too expensive. Likewise, 32mm waste pipe is 3.5 times as much.

The stumbling block at the moment is working out how to turn the pump off once the loft tank is full. I am aware of electric float switches, but just not sure how to wire this up. Any help and advice on this would be greatly appreciated.

It would be nice if there was a website dedicated to cheap DIY systems, with pictures and tutorials of how people have done it. Once mine is complete, would love to share it with the masses.

gromituk

If you're interested in minimising electricity consumption I would have thought that 32mm waste pipe would be better - the tank will fill much more quickly. Mail order it shouldn't be too expensive. Regardless of what you do, make sure it doesn't have any low spots so it will drain completely when the pump is off and so will not freeze.

You wire float switches in the same way as any other switch, but I'd use at least two in series because the consequences of the pump not switching off are fairly disastrous. Again to minimise electricity consumption (fewer and longer cycles), you'd want a large difference in level between the point where the pump switches on and switches off - difficult to achieve with a simple switch.

beetlebum_2

After doing a quick experiment with a small tank in the loft, I wasn't too happy with the slow fill rate of my toilet's cistern (due to the fact I only have about 2.5M of head).

Last week I stumbled across this website: http://chrismi.com/rainwater/ which gave me the idea to try a pressure boosting pump. I ordered one off ebay for 60 odd quid. Haven't had too much time to play with it, but initial impressions are good. So with this, I can have a direct feed to the toilet and washing machine and will provide at least 1.5 bar.

Andrew: Interesting video. I like the idea of the 25 micron sock on the inlet pipe. Going to order one of those today to give finer filtering. As I said in my previous post, I use a 3P filter that removes most of the stuff, but obviously doesn't filter out the really fine stuff.

gromituk

The trouble with putting pumps like this in is the amount of energy they take. I wonder whether you're losing out overall.

beetlebum_2

After plugging in an energy monitor on to the pump, it uses about 650W. So. to pump 1000 litres of water will only cost a few pennies. Haven't measured the flowrate yet, but it's quoted at 3800l/h. The pump has a 1" outlet, which I will be connecting to cheap 21.5mm overflow pipe. Not only that, I get the added benefit of being able to use rainwater with my washing machine. Most need 1 bar (my Bosch does), although I believe a couple of manufacturers only need 0.5.

beetlebum_2

Just thought I'd update you with the progress on my rainwater harvesting project. I've been quite busy with it the least few weeks and I'm just about there.

As it stands at the moment, this is my setup:
As previously mentioned, I am using a booster pump to supply water the the upstairs toilet and the washing machine. The one I originally got has gone back and has been replaced by a 700W Clarkes CPE100TF one (which I got for a bargain off ebay). Using my energy meter, it uses 500W and has a great inlet filter. This is in sited in the shed.

Next to the shed I have an IBC container. I have acquired 2 of these, but at the moment only have 1 connected. I removed the heavy metal cages from them too, as it would have been a major tasks to get them in the rear garden otherwise. The container is connected with 32mm MDPE pipe (which I managed to get 3.5 metre from Freecycle).

The cold feeds from the pump is run in 15mm speedfit pipe which I got on a coil. It certainly made it very easy to route the pipe under the kitchen units to the washing machine.

Finally, I altered my gutter downpipe, to fall on the kitchen extension roof. That water then goes into that roof gutter where I have then installed the 3P filter/diverter. From that, I have connected 32mm PVC waste pipe to the top of the IBC. At the end of the pipe, I have attached a 25 micron filter sock for finer filtration (thanks for the idea Andrew). All I need now is some rain!

Once the 2nd IBC is in situ, I will post some pics with details to show how I done everything.

So far it's been very educational and rewarding. I know most of you seem to be using a submersible pump and header tank, but having tried this option, it wasn't for me, especially as it didn't create enough head to run my washing machine. Also, couldn't get my head around wiring up a float switch. Not only that, most float switches seem to be rated at 1A, which is too much for the submersible pump to handle. The Junior Hippo would have been fine, but didn't have enough guts to pump water into header tank.

Ken68

Would pouring rainwater thru the detergent access work OK. ?
I presume there is a float switch of sorts to tell the washing machine when there is sufficient water.
Would save on mains water.

beetlebum_2

Ken68 wrote: »

Would pouring rainwater thru the detergent access work OK. ?
I presume there is a float switch of sorts to tell the washing machine when there is sufficient water.
Would save on mains water.

Hi, when looking into this, I found this webpage, which made interesting reading:
http://www.whitegoodshelp.co.uk/wordpress/low-water-pressure-and-washing-machines/

Ken68

Blimey, Beetle, lots of info there, like War and Peace.
Read something there which explains why my BEKO machine uses less water than normal. Nonetheless washes well enough.
I have a manual solar hot water system which produces hot/warm water by about 5pm in the summer, so thought to save water and electric. However opted to use said hot water to pre- soak clothes overnight instead.