Medium Scale Rainwater Collection

[Briggs]

I have an ongoing project with the aim of storing up to 2000 litres of rainwater. I thought I'd share my thoughts and progress so far.

I plan to use multiple IBC 1000 litre storage tanks because these are less costly than underground storage tanks and the storage tanks provided by rainwater storage systems. I was a little concerned with the clear plastic tanks if left out in the sunlight would become an algae breeding ground making the water stagnant in a few weeks. I saw a prepper in the US has overcome the direct sunlight/algae forming problem by removing the plastic tank from the metal cage and wrapping the tank in thick UV protective black wrapping, then fitting it back into the metal frame. (I have noticed some black coloured tanks for sale but I'm not 100% sure these are UV proof plus the clear ones cost less so I'm going down the wrapping route).

Rainwater will be collected in the usual way from the roof but I plan to pre-filter the water in the downpipe using the type of filter medium you find in garden pond stores to remove the moss/leaf/bird poop medium.

My plan is to then have the 1000 litre tanks connected in series. The first tank will be pre-filtered by gravity through the filters in the down pipe. In between the first tank and the second tank, I'm planning on fitting a low voltage garden pond pump and three stage filter which I will power by battery and solar panel. I will fit a one-way valve so the filtered water is fed into the second tank and cannot be contaminated by contact with the first tank. By using a garden pond filter with three-stage filter and a UV filter, the water in my second tank will be Koi-Carp quality clean which is good enough for washing and boiled for food-prep.

Water from the second tank will then be filtered into drinking water and I'm currently considering using another three stage filter and UV steriliser with a drinking water certification or I may opt for a simpler set up using a British Berkefeld no-power-required filter to get our drinking water.

Total kit required:

2 x IBC containers, a home-made downpipe filter, a Hozelock garden pond pump and suitable solar panel/battery. Then the Berkey filter for drinking water. I'm figuring this is going to cost about £400

to £500 but will be worth it in the long term to have a ready supply of water at home and at my off-grid location.

I'm aiming to install this set-up at my off-grid location as a permanent water source so 2000 litres may be too big for your requirements (after all you can't bug out and take 2000 kilograms of water with you) but the idea of the garden pond filter could easily be adapted to smaller water butts in your garden/balcony and the Berkey filter is a good idea if you were planning on bugging in and using the cold water tank or a filled up bath as your emergency water supply.

It's not just about being self-sufficient in water, I'm driven by the ever-increasing cost of utility bills. My water supplier, South West water meters me on the water they supply to the house and then charges me three times that rate for the waste water and sewage removal. SW Water assume what they supply into the house, must be going out as waste water so, by not bringing in some much water via their metered pipe, I'm effectively reducing what they can charge me for sewage/waste water. Check your own water bill and you should see the cost for incoming and outgoing water so if you can collect your own, your savings are potentially three fold.

Any comments or suggestions will be most welcome

[grenfell]

I'll comment on one thing if I may.
I can foresee one flaw in your plan and that is to filter the water in the down pipe. Filters by their very nature slow down water flow and you may well find that in heavy rain the downpipe will back up and overflow the guttering. I'd perhaps take water into one IBC container and then a filter between that and the next one with an overflow to a soakaway on the first. The first would thus always be unfiltered but would be perfectly good for watering, washing , and flushing toilets.
I have heard that some people who use these containers have problems with the fittings as supplied leaking and have to redo them. Also check there has been nothing nasty carried in them and that they have been well cleaned.

[Briggs]

I'll comment on one thing if I may.
I can foresee one flaw in your plan and that is to filter the water in the down pipe. Filters by their very nature slow down water flow and you may well find that in heavy rain the downpipe will back up and overflow the guttering. I'd perhaps take water into one IBC container and then a filter between that and the next one with an overflow to a soakaway on the first. The first would thus always be unfiltered but would be perfectly good for watering, washing , and flushing toilets.
I have heard that some people who use these containers have problems with the fittings as supplied leaking and have to redo them. Also check there has been nothing nasty carried in them and that they have been well cleaned.

Thanks for the comments. You are right, the downpipe filter is something I do need to test for flow rate. I intend to start off with three different filter pad and then remove them one by one as and if flow rate is an issue.

Where I am, the farms use these containers for everything from red diesel to sheep dip so I will be steam cleaning them thoroughly before use.