Catching rainwater

[kristen]

I want to catch the rainwater.  Retro-plumbing a system to fill the bog etc. would be difficult here (solid concrete floors, long pipe runs, etc.), however we have a pond and large vegetable patch, and last year we had a large water bill for using the hose.

I have managed to find one soakaway - its only 10' from the house (plastic sheet covering some builders rubble, so pretty basic!).  The others are not so obvious.

I reckon I have two choices, but I would welcome ideas and opinions please.

1) Dig a trench round the house, intercept all the pipes-to-soakaways, link them, take the water to a single point for re-use.

2) Take each downpipe into a water butt, and have some 1/2" or 3/4" pipe to some central store.  Heavy rainfall will overflow the butt into the original pipe + soakaway (maybe a pump would reduce such wastage?).

(2) would be easier to install, but might look a bit unsightly.  We have large [cast iron I think] downpipes, so the standard diverters for water butts won't fit.

Not sure what to do with the water once I've got it to a central point.  One thought was to make the drainage pipe an integral part of the pond - so when the pond is full the pipework will be flooded too.  There is a fall towards the pond - about 0.5m over a 30 m run, that's the the top of the pond, and its won't be "full" in practice.  I could then pump from there to the Veg patch.

Alternative is a tank, and then pump to Veg patch or Pond as appropriate (and resort to mains water when necessary).

The house has a downpipe at each corner, and a 5th at the end of the attached garage.  There is also a large covered area with no gutters that just runs off at present (perhaps put a land-drain around that, as well as some areas of the garden I would like to drain, that might give me some more catchment).  The site is pretty flat

I could have a borehole I suppose ....

Kristen

[stephen]

Kirsten,
Bore holes will cost you anywhere from £8000 to £12000 so it’s a bit expensive.
You can get pumps with a small diaphragm in them that activate when there is a flow of water. 12v ones are available from boat suppliers or machine mart type companies do the 240v.
Have you also looked into sending the water into an IBC (intermediate bulk container) which tend to be 1000l and can be found on ebay for about £20.  Also to a google for orange containers they used to hold liquid orange prior to putting them in cartons.

Just some ideas

Stephen

[kristen]

Last summer we spent £ 8 per day on water.  We had two leaking ponds to try to keep the plants alive in, and discovered a leak on the swimming pool (which has automatic fill).  So I have no idea how much was wastage, and how much we actually needed.  We didn't have any vegetable patch to water at that time, but if that were to become our normal usage then a bore hole would look cheap!

Our water usage is now about £ 0.50 per day.

Thanks for the info about the pumps, and the IBCs - didn't know about that, I'll have a Google.

Any idea whether I should pump out of a sunken tank direct into the irrigation, or should I build a header tank and trickle-pump up to that?

Kristen

[stephen]

The pumps will pump up or down hill and most dont need priming.

We have a farm and use about 0.5-0.8m3 per day. We have sheep which dont drink much 5 horses + girls washing horses etc and 2 houses.  this summer we are putting in a system similar to what you have described for washing the yard down, flushing outside toilets etc. so it should come down a bit.

You should be able to make one claim for a large leak per household per 5 years i think.

let me know if you need more help

Stephen

[SteveK1]

Hi,
1.What about connecting two IBC's together, (in a shed for insulation and to keep them in the dark) next to your house. Stand them on a couple of pallets to get a gravity head sufficient for a trickle to your Veg. Route your downpipes to these.
Rainwater is not advisable for Ponds/Pools as it promotes Green algae but you can use a UV filter to beat that, (also useful to clean Non potable water a little more and zap those nasty viruses, bacteria and protozoa). This will keep the costs down.
2. If you want to spend a bit more simply drop a pump in, triggered either by a drop in pressure on a seperate system when you flush a loo or to another header tank in the loft. you will need a mains feed to top up the tanks if they run dry though?
Don't forget your rainwater will be unsuitable for your pool unless you can be sure all those evil bugs have been killed, (remember a roof is a Bird toilet!)
Onward we stumble.....
Steve K

[kristen]

Thanks to Steven I have now had a look at IBCs on eBay.  As he said: "Dirt cheap"! and there are plenty available in Black, so that seems like a good idea.

Can I stack them vertically, perhaps with an Overflow to the next-lower-tank?  How many high?

I don't really want them stood next to the house (even a water butt is going to be a problem because my downpipes are much bigger than the standard size T-connection into a butt - they look like they are cast iron - also, they would look unsightly)

So I reckon my best bet is to sink a small "sump tank" next to the down-pipe, route the rainwater into that, overflow into the original pipe to soak-away, and install a submersible to pump the water into some storage right next to the veg. patch.  I think running a drain-pipe all round the house intercepting each down-pipe is going to be too difficult - a 1/2" pipe from a submersible would be much easier to retrofit.  (I'm assuming that the submersibles would filter out the muck, and the sump-tank could be cleaned out regularly;  maybe a 3/4" pipe would be better?)

IBCs might well be the answer to the storage side, but I have seen some large "Titan" tanks for not a great deal of money.  The only IBCs I've seen are 1,000L whereas the Titan is 5,000L

I reckon the pond will be about 200 sq.m, I suppose an average of 0.5m deep, maybe less, so somewhere in the region of 100cu.m of water.  I read somewhere that evaporation in the summer will use up 1" per week, which is about 5 cu.m / week.  Average rainfall here is 20" per year (average 2"-2.25" per month Aug-Nov, 1"-1.5" per month the rest of the year)

My total "collecting area" is 400 sq.m with gutters, and a further 300 sq.m without gutters

I am also wondering whether I could use the outfall from the cesspit for something useful.   Given that its too hard for me to retro-plum grey water to the bogs etc., maybe using mains water for the bogs but pumping the cesspit outfall onto the veg patch would accomplish some re-use.

There is also the backwash water from cleaning the Pool, which I always think is a terrible waste - is has a fairly high chlorine level, so might need a settling tank?

(The cesspit is really old, and must be getting close to needing replacement, so as part of that I could perhaps look at something that will make the water clean-enough for the veg patch, or maybe even the pond, but right now whatever is coming out is going into the ditch, or maybe a soak-away ... so could perhaps go on the veg patch).

If the roof is a bird's toilet I suppose putting the cesspit outfall into the Ponds is A Bad Idea!

Kristen