Rainwater harvesting

gromituk

I have a large pond in the garden, and right from the beginning I planned to try to feed it with rainwater as much as possible. To that end, I dug a hole under the decking which the pond surrounds, and lined it with pond liner. This holds about 5000 litres. I originally fed it just from the gutters at the back of the house, via a simple strainer made from brass mesh sitting in a hopper, with stainless steel pan scourers on top. This catches some of the larger bits. I have also put leaf traps along the guttering.

I have since extended the system so that it catches water from the front of the house, too. Quite a bit of extra piping was needed, and I have a "rainwater switch" consisting of a "shoe" above two hoppers. You can rotate the shoe to send the water down the drain or to the reservoir. I hardly ever send it down the drain - the reservoir has a soakaway which is much better than sending rainwater into the sewers (reflected in the fact that it is required under the building regs for new properties and extensions). There is a downpipe at the front of the house but I have angled the gutters to encourage the rainwater round the back. I have put a short stub of pipe in the top of the front downpipe so that no water goes down it except in heavy storms, when otherwise my long lengths of gutter might overflow.

As I am in an end terrace with downpipes only on alternate properties, I get the benefit of most of next door's roof too. Fortunately my neighbours are not gardeners or they might feel a bit cheated!

I have a submersible pump to fill the pond from the reservoir. Yes, it uses electricity but not that much.

I have recently been thinking about using rainwater for toilets. As I don't have any proper filters I haven't considered it for the washing machine/dishwasher. I bought a secondhand cold water cistern from eBay and some solvent-weld 32mm waste pipe but that's as far as it's got. The plan is to put another submersible pump in the reservoir and feed it up the back of the house in 32mm pipe to the cistern in the loft. The pipe will be self-draining to avoid freezing. Because it drains each time the pump switches off, it is better to have the pump running infrequently and for longer periods, and to this end the cistern I have bought is quite large, and I intend to fit two float switches at very different levels - one to switch the pump on and one to switch it off. A third switch will act as a safety cutout and there will also be a timer to cut the pump if it's running for longer than anticipated - the last thing I want to do is flood the house! A fourth switch will kill the system if the reservoir is too low - a float valve connected to the mains water (via a non-return valve, as it will be submerged most of the time) will cater for droughts.

I will feed two toilets and an outside tap from the cistern.

As you can see, this is quite a palaver and only really worth it as a challenge!

gromituk

apples1 wrote:

We have to keep the cast iron guttering/ down pipes. Its a listed building and we are not allowed the plastic ones.

Ah OK. Also, I was wrong about rainwater goods - they are in PVC.

I wouldn't be surprised if you find a water butt adaptor that's compatible with cast iron, or some other solution such as extruded aluminium, which is fairly indistinguishable.

yds3

Use an aluminium downpipe, paint it to the colour of your cast iron pipes. Plastic is hard to recycle, I know, I have tried to get plastic tubes recycled as we used a lot.

The other thing is that if you are usiing a pump, get a solar one or convert it to solar. Why? Because its not just about saving water it is also about reducing our carbon footprint.

If anyone has the cash and land, dig a borehole to the water table and you can, so I have read somewhere use 2200 gallons of water a day. I think the cost will outweigh the benefits.

Every action has a reaction - causal effects

woollyjumper

GrommitUk - How long does it take to paint your decking if it is covering a tank that holds 5,000 litres.. Sounds like a full-time occupation to me ! :rotfl:

Luckily or Unluckily don't have a pond - so it down to just watering the garden and possibly the toilets - if I get a big enough tank fitted in the garden .. but keeping away from the commercial systems the costs don't weigh up so as grommit says add it to the DIY list !

gromituk

Doesn't need painting fortunately! But 5000 litres isn't that much - a hole 3m by 3m by half a metre deep, approx.

cazrobinson

if any of you get permaculture magazine, there was an article there about water usage and a lady has just made a diverter, so the water could switch from drain to feed watering can or an old hosepipe laid in flowerbeds with holes in.

very cool!

gromituk

cazrobinson wrote: »

if any of you get permaculture magazine, there was an article there about water usage and a lady has just made a diverter

I've got my own rainwater switch - the pipe comes down over two rainwater heads (hoppers), and I turn the shoe on the end one way or the other to send the rain into my "reservoir" or down the drain.

Seakay

bridiej wrote: »

You need to be careful about storing water used in things like showers, laundry etc as it can breed all sorts of nasty bugs. It's also not recommended to use such water in sprinklers or hoses either..... I know there are laws against that here becuase it can be quite nasty. And you should use that type of water on any food plants either.

I am really keen to reuse rain water as there is a water shortage here although you'd never know seeing the amount that gets wasted on people watering their gardens with sprinklers!! (they have no ban here)
:rolleyes:

If you use eco friendly washing products then there is no problem with using it for any watering - friend of my sister in Melbourne has a pipe attached to his washing machine outflow pipe to take all the water straight down the garden - even the sudsy stuff! Might even help with aphid control if you have that problem.

I store the water from the spin cycle for up to a month and it seems ok as it is not very soapy - I use a reduced amount of the eco stuff and don't collect the first rinse water which is very soapy and which starts to smell if kept for more than a day or so (I experimented with a bucket!)

gromituk

Sounds like a great project, but it also sounds like you are in the very fortunate position of being able to have a supporting structure (a hill?) capable of holding 3 tonnes at a level above the taps in your house! I have a less ambitious project in mind to pump water from the "reservoir" I use for my pond up to cisterns which then feed the toilets. The pond uses a lot of water so although I collect from all round the house and next door (end of terrace) I still barely have enough a lot of the time.

Fred56

Andrew, very impressed with what you've achieved there. I've looked at this myself but the package systems are over £2k which made it uneconomic. We were off mains for sewage for that house so I was putting in a treatment plant and was already geared up for excavation. I was keen because I stayed with my brother out in Aus. There are no water or sewage systems at all where he lives and he harvests rain. To drink it they filter through a half micron filter. When he runs out of rain water he just pumps some water out of the river that flows through his land.
The filters are available here, I've fitted one to a single tap to stop my wife buying bottled water. We get scummy tea if we use straight tap water. Works a treat.
Keep adding news, I'm really interested.