Water matters.

A week ago we were on day four of a severe weather warning for high temperatures. We were also, and still are, experiencing a very dry summer. The world is getting warmer and the rate it is doing so is accelerating.

I already have a fairly complicated water harvesting setup but my stored water ran out leaving me using metered tap water. My thoughts turned to ways of increasing my storage.

If space wasn’t an issue I would install a galvanised steel tank with EPDM liner. Suppliers will tell you they are the most cost effective solution for large volumes of water and so they probably are. Historically our area gets 1250-1500mm of rainfall pa and I can collect water from about 100m² of roof. That equates to 125,000-150,000 litres of water pa. It would be great if the 100m² was a single roof with space available alongside to install a tank of perhaps 10,000 or 20,000 litres capacity. I would surely never run out of water again. Sadly, I am drawing water together from a number of roof areas and moving it about by various means.

Looking at one tank supplier, they offer a 9ft (2.76m) diameter tank in various heights. At 1.52m high it has a capacity of 9,120 litres and costs £1901.74. An anti algae cover brings that up to £2261.72, a steel roof to £3359.74. That’s a range of roughly 22-37p per litre stored.

The 3.84m high version holds 23,050 litres and costs £3208.54, £3568.52 or £4666.54 for the same options. That’s around 14-20p per litre stored.

An 18ft (5.53m) diameter tank, 2.28m high, holds 54,760 litres and for the same options costs £3708.26, £4471.46 or £6828.26, equating to 7-12.5p per litre stored.

The tank would need a concrete pad to stand on, adding to the cost. Being assembled on site, access is not the issue it becomes with a large plastic tank.

The same company offer polythene tanks in various sizes but even the 2,500 litre version is 1400mm wide; too wide to get into our back garden without a crane or taking the fence down. It weighs 55kg, could it be lifted over the gate? At £816.95 it equates to 33p per litre stored. They offer a 720 litre tank which is 700mm diameter but it costs £615.94, a cost per litre of 85.5p.

Another alternative would be reconditioned IBC’s. The same company offer them in black and including delivery, three would cost £502.20. At 1000L capacity, that works out at 16.74p per litre stored. Still too big to go through the gate but could be dismantled and manhandled. For a given volume of storage they take up more space.

I found and was intrigued by the idea of a PVC collapsible water butt. At £150 for 1000L capacity it is an inexpensive option and it could be put away when it was empty. The blurb said collapse and store in winter but that is when it would be filled, to use in summer.

Hmmm. Options, lots of ’em. And questions, where will it go? How will it look? What other costs are involved? Is it enough or will I need to add to it in a short while?

I’d be interested to hear if you have thoughts or experience in this area; there must be many angles I haven’t considered. While I was writing this piece, it was raining outside. Heavy for a while, then a long tail of drizzle. My rain gauge recorded it as 8.2mm, so another 730 litres has been captured and will be put to good use.