Harvesting rainwater for drinking

[Islay]

My parents have had enough of the vile water that they are getting from the mains, and are contemplating attempting to harvest and drink rainwater. They (and I) have absolutely no idea where to start with a system, have any eco-builders got any ideas at all? Any thoughts much appreciated!

[Green Aura]

I don't have huge amounts of knowledge but have looked into it some. But before that one thing springs to mind - do you get enough rain?!!

Anyway, if the answer to that is yes, space permitting you can get huge tanks that go underground or not so huge ones that sit at the side of the house.

You need to do some research on how to keep it sweet, in storage, and then you have to treat it to make it potable (drinkable). The best, small-scale method I've seen is a UV light system that the water runs through, as you pour it. A cottage we stayed in a few years ago had one of these. It was a small box, approx 2 feet high x 6" wide, fitted to the wall in the outhouse laundry room - it glowed eerily in the dark They were treating spring water though.

I think keeping the water clean enough to drink will be your biggest problem - large reservoirs of water attract all sorts of things, which may not be a huge problem to water the garden with but you wouldn't want to drink.

Oh, and you probably need to check out any legislation - even households are covered by so much legislation these days!

[Islay]

Thanks for that - I think lack of water is not a problem - they live in the Welsh valleys. Too much water, maybe...

Hadn't even thought about legislation, I'll get them to give the council a call, so thanks for thinking of that!

[KathyLauren]

I only use rainwater for irrigation, but I have looked into what would be required to use it for drinking water.

You would need to start by looking at the material that your roof is made of. Metal is the best surface for water collection. Asphalt shingles or wood are likely to trap gunk and grow stuff, which you want to avoid.

You would want a sediment tank between the eavestroughs and the main tank. This is a tank big enough to hold the first few gallons of a rainstorm. It has an intentional slow leak in it, so it empties itself after the rain stops. Basically, it traps the first flush of a rainstorm, which washes any contamination off the roof. Once it is full, then the overflow from it goes into the collection tank.

The water in the collection tank is going to get icky no matter what you do, so you need purification between it and the kitchen taps. Someone mentioned UV. It is effective, but it has some drawbacks: it uses electricity; it must be on all the time; you need an alarm in case the bulb burns out; you need good filtration so bacteria can't hide in the shadow of a speck of grit; the bulb must be replaced every year, whether it burns out or not.

An alternative is a ceramic filter. These filter the water through a porous piece of pottery. The pores are small enough to remove bacteria. Drawbacks are that the filter must be cleaned regularly (3 or 4 times a year) and eventually replaced; you need a good pump to squeeze the water through it. On the positive side, you only need to replace the filter once every few years, and it doesn't consume electricity. We have one for our well water, and like it a lot.

[Millymollymandy]

I don't know anything about collecting water for drinking but I would say avoid collecting it from any roof which has a tree overhanging it. We've got some kind of problem up on our corrugated iron chook shed roof which has an overhanging sycamore - OH has cleaned the gutters (not dirty) and looked on the roof (no dead rats!) but we are collecting green, stinking, festering bubbly water in our 500 litre water butt. I don't know how, and we emptied the whole lot out, cleaned the butt and it refilled with recent rain.... only to have a layer of festering green algal gunk on the top and all the water is bubbly and stinking again.

I can only blame the sycamore tree, but we've never had this problem before. It's a real pain as this is the butt we normally use for the duck and chook water but it is so bad I am scared I'm going to kill the non edibles (as I'm not putting it on my veg!!!).