Hi Guys,
I'm after a bit of advice on my plans for rain water harvesting... My house currently has surface water fed into the combined sewer system, for which evil Southern Water levy a standing charge. They've also just installed a compulsory water meter, which is going to hurt as I have a large garden to water, and some small people in the house who have a profligate daily bath regime! I'm in the process of building a new driveway, and decided that some 'underground workings' might be in order to initially divert water to a soakaway. Phase-II is to harvest the water mostly for garden use, but potentially also for toilets by filtering and pumping under pressure back to the house. I'm not comfortable with using it for laundry though, as I would worry about bugs growing in a 40C wash, and would need to implement some sort of full-on treatment, which doesn't sound cost-effective. Anyone have any experience here on cheap treatments?, as (again, thanks to those messy Small people) the WM is a major user I'd like to get of my bill!
The current idea is to make a 'sump' out of an inspection chamber built under the drive. Water will be collected from each of the downpipe locations on the drive side of the house, and will be carried underground to the sump. It will then overflow into a soakaway. This ditches the nasty surface water charge
and provides an escape route for water if the harvesting system breaks. The sump, and underground pipework will fill up to the same level, acting as a store. I'll have a bilge pump in the sump controlled by a high and low water level. This will pump the sump dry, with the water being pumped around to the back of the house where it will join water from the one rear downpipe, and then flow by gravity into one (or more) IBCs in the garden. I'll probably have some sort of sand filter in the feed to the tank.
I'm expecting that the sump will catch quite a bit of muck that'll I'll have to clean out occasionally, but I don't see that as a problem as it means I don't need to bother with 1st-flush arrangements.
Quite impressed with this rain water harvesting lark. I'd dismissed it in the largess days of pre-meter, but a diy install is very cost effective. Taking only the surface water charge alone, and using just the soakaway, my pay-back is in the the order of <5years. I can't wait to start harvesting... each 1000L IBC full is worth £3 at the current rates, and I bet they rapidly go up :-)
Nick
