Time to rethink rainwater harvesting?

mmmmikey

It's just started pouring with rain so I've come inside for a cup of tea and now seems an appropriate time to create this post

Anyone who's looked at rainwater harvesting (in the UK!) in the past is likely to have come to the conclusion that it doesn't make much sense in pure financial terms and may not ever pay for itself.

Notwithstanding that, I had a problem with drainage in my garden a few years back and whilst I was sorting it out I installed an underground rainwater tank - not in the expectation of saving huge amounts of money but thinking that even if it never paid for itself it wouldn't fall far short, it would be good for the environment and it would protect me from future increased water costs. I was also in the nice position of knowing that it wouldn't bankrupt me if it all went wrong and I enjoyed the challenge of digging the hole and getting it all installed and working. I bought a package for about £2000 which included the tank and a pump / mains backup unit, and spent maybe another £500 or so on bits and bobs to get it all installed. For one reason and another (mainly because I really wanted to remodel the bathroom first) I've only just got round to installing the pump and associated equipment, and I'm kicking myself for not doing it sooner. I'm now using rainwater for laundry and toilet flushing as well as watering the garden. It's been up and running seamlessly for a couple of weeks now - long enough for me to be confident that I'll see a saving of £200 to £250 per year on my water bill.

The point of this rambling post is that for me rainwater harvesting is starting to make real financial sense, with a payback in ten years or so at current rates. It also seems inevitable to me that water costs are going to rise steadily over the next decade or so to fund the desperately needed investment in new reservoirs, replacement of aging pipework and generally redesigning the systems to cope with changing weather patterns and increased population. So something (rainwater harvesting) that was a bit of an extravagance is now looking ( sort of  ) sensible.

I'd be surprised if you could make the numbers work if you were paying someone to do the work, but I do have the impression that this is now a viable project for keen DIYers (but just a note of caution on that - you need to appraise yourself of the regulations so you don't kill all your neighbours by contaminating the public water supply, something that is frowned upon in many places).

Has anyone else looked at this either in the past and/or re-run the figures at today's costs? Anyone thinking of trying it?

The rain has stopped, going back outside now to check the level in the tank. I should have enough rainwater stored to last me into July now. A bit of sunshine to charge the solar batteries would be welcome now

FlorayG

I know someone who does this with a couple of IBC tanks on the side of his house - he doesn't get as much water, but there's no digging involved and there's enough water outside of summer for all the domestic uses

MattMattMattUK

I know a business who does this, not to save money, but for the environmental benefits. The water from the roof of their office and warehouse goes into a tank which flushes toilets and is used for watering the grounds. Not really any direct saving, but it does mean that they can water the gardens when there is a hosepipe ban.

Rodders53

I worked at BBC Broadcast Centre, White City where they had rainwater harvesting off the roof to flush toilets.  They soon reverted to mains water for the toilets as the water was "dirty" and staff complained and the required filtering in the too difficult pile.

This house was built with rainwater harvesting.  I'd not use the water for washing clothes.  Again the water can leave  grubby marks and algal growths in toilet bowls.  It probably does save us half our (low) water use, though (3 cu m per month cf 6 cu m per month in our previous property).  SWMBO wants it switched back to mains (as we have to do when the tank runs low) for cleaner loos.  Does a good job with car washing though cf the hard water here.

***  The install was poorly done and the pipe / auto mains water refill system in mine is flawed (the MDPE take off pipe/float has a 'memory' so never reaches the lower end of the tank to operate the float switch/water solenoid.  I had to replace an expensive control switch that failed (leaked).  Others in the small development have had problems also.  At least one has abandoned it. 

A local garden centre is very proud of their rainwater harvesting for plant watering purposes.