Rainwater Harvesting - is it Green & Ethical?

Reed_Richards

QrizB said:

...Managing it and treating it {water}, so you have enough potable water all year round, well that's another matter. Buying it from the water co is almost certainly the moneysaving option, and could be the green and ethical option too.

I have been toying whit the idea of collecting rainwater in a big tank and using it to flush the toilets as well as to water the garden during the persistent dry spells that seem to be increasingly common.  This is sufficiently expensive that the payback period would be huge as to be almost certainly not money saving.  However I had thought that not watering the garden with water bought from a water co. was green and ethical so I would be interested to know why not.  I already have a 350 litre water butt but that really doesn't last very long.   

ABrass

I think the key bits are potable and 'all year'. You're not describing potable water, rain runoff from your roof does require treatment to be potable. Also storing that water in a potable state isn't trivial.

Rainwater for toilet flushing and the garden is green by any sensible metric.

mickyduck55

I have a 1000 litre  BIC container that stores water from my garage roof and a few other water butts some are connected to the the roof others I just fill from the BIC.  I rarely used my garden hose for anything except filling the granddaughter's small paddling pool.

I pump the water from the BIC to the butts that are not connected using a submersible pump powered by electricity generated from my solar array.  It takes time and its a bit of a pain but I feel good about doing it this way.  The ROI is not even worth thinking about .. I had to buy a pump, have two wooden old whiskey barrels and a plastic butt connected to my shed roof.. probably spent £200, the barrels both have cast iron hand pumps so are decorative as well as functional... as I said I do it because I like the idea.

michaels

I guess it depends if the large plastic tank you need plus all the other bits and pieces use more plastics and energy (of which some will be released as microparticles) 'per litre of water' over their lives than the same volume of water supplied by the utility - bearing in mind that you might be more sparing with water if it comes from the utility.

I wouldn't like to even guess which option is actually green rather than greenwash.

mickyduck55

My BIC tank was just laying empty on a friends farm so cost me nothing.. clearly at some point it did cost someone something.. The wooden barrels are recycled from a distillery... as I said I like the idea.  Like "Micheals" above I have no idea if its green.

silverwhistle

Eminently sensible idea and no downsides. I just have space for a butt feeding from my outhouse roof and it's a particularly useful resource for the acid loving plants. I also run the taps into a watering can for either fresh water in the morning or to let it run warm for washing up etc. It's not so much due to being metered, but living in the water stressed south-east I'd rather my local stream had a healthier flow. We should have much higher standards for all the new builds being built round here..

ABrass

michaels said:

I guess it depends if the large plastic tank you need plus all the other bits and pieces use more plastics and energy (of which some will be released as microparticles) 'per litre of water' over their lives than the same volume of water supplied by the utility - bearing in mind that you might be more sparing with water if it comes from the utility.

I wouldn't like to even guess which option is actually green rather than greenwash.

But then you've got to factor in that many properties also have shared sewerage systems so by diverting some of the rain you capture you reduce the stress on water treatment facilities and thus save dolphins. Also by watering your plants you help slow storm surge.

Also by avoiding drawing down other fresh water supplies you reduce the environmental impact of them and load on ground water.

Water butts should last a decade or two, I doubt they expell much microplastic particles either if properly recycled.

Being sparing with water is great, unless it's free and you're helping the environment by using it rather than letting it just run down the sewers.

If you try to go to extremes then you can make anything look bad.

QrizB

ABrass said:

I think the key bits are potable and 'all year'. You're not describing potable water, rain runoff from your roof does require treatment to be potable. Also storing that water in a potable state isn't trivial.

Rainwater for toilet flushing and the garden is green by any sensible metric.

This is exactly what I was getting at. You can do lots of things with raw rainwater and a coarse screen to take the lumps out - flush the toilet, water the garden, top up the pond, wash the car, perhaps wash laundry.

But ensuring it's fit to put into a human body is relatively expensive and, on a domestic scale, resource-hungry.

EricMears

Of course it's both green and ethical.  More to the point (on this site) it can also be hugely money saving.

My 4 IBCs in the basement cost absolutely nothing as did the 'redundant' pump I fitted.   The header tanks in loft and a small amount of wiring & plumbing cost less than £100.

Apparently,  water for WC flushing accounts for approx a third of domestic consumption - in which case using rainwater is an immediate 'discount' of one third of metered water charges,  But it gets better :  if you're on mains sewage (I'm not) then sewage isn't measured - just estimated from metered input - so you'll get a similar discount on sewerage charges.  And if your rainwater is normally sent to a sewer,  that would be a further item on your water bill that you can avoid.

The minor inconvenience of having an extra tank in your loft is quickly overlooked the first time you have a loss of mains water supply lasting more than a couple of hours.  Which clown decided that dispensing with a header tank was a worthwhile saving ? 

michaels

Reuse is always environmentally friendly if the alternative is something will get thrown away but in an overall comparison it would not be possible for everyone to reuse pumps, tanks etc. I have no idea if more energy is used for you pumping the grey water to your loft than the utility company use to supply the same volume to your home.   Obviously energy and resources were used in the additional tanks, pump etc, again we would have to compare it to the utility resources used in supplying the same volume.  We also need to look at the environmental impact of the decomposition of any plastic tanks and their end of life processing.  I suspect outdoor plastic items do shed Nano particles but no idea at what rate - also how are they recycled, is it mostly incineration to provide heat and power?

The good thing is that water is not lost in use so at least we can say that beyond evening the flow, the storage and domestic use of rainwater will not impact on local water tables.

EricMears

michaels said:

 I have no idea if more energy is used for you pumping the grey water to your loft than the utility company use to supply the same volume to your home.   

Exactly !

However,  I do know - almost exactly.  Pump draws 500W and runs for approx 5mins/day to raise 100litres.  It's always run at cheapest possible rate - which at this time of year is usually zero ppu (from solar power).  It would be something of a miracle if Severn Trent could get anywhere near matching that !