You remember how we first got interested in grey water? Fear of the municipal account. Do you remember what made me realise it wasn’t going to be as easy as ‘pour it into a 25l drum and relax’? Fear of the hospital account! That drum smelled dangerously foul. The water went down the drain and I got started on an information hunt.
Sifting through all the information and misinformation on the internet took hours but I am grateful I did it. I happened upon this site and found excerpts from the book Create an Oasis with Grey Water by Art Ludwig. Art is an ecological systems designer with 35 years full-time experience in water among other things. He seems honest and his information is free and complicated. No easy answers here! Which makes me trust him. Art does not know I exist and I am definitely not earning anything from this post. I just want to share what I learned.
Don’t store grey water more than a day
Firstly, I learned that it is best not to store grey water for more than a day. The bad microbes in the water multiply making the water smelly and oxygen poor. A system that drains completely as soon as the water is cold, gives maximum benefit.
24 hours is generally considered the prudent maximum time for storage. Since this is not enough time to, for example, store grey water from a time when irrigation is not needed to one in which it is, I find myself tuning designs to eliminate pooled grey water anywhere it occurs; just send it all straight to the soil. The fewer little anaerobic corners and pockets the better. My latest designs drain COMPLETELY…all the collection plumbing, distribution plumbing, and surge tanks (if any) slope at least 2% across their bottom surfaces.
He carries on saying that in the case of treated grey water it could be stored longer. That means that if you use Mrs Martin’s HAND and BODY (or any of the other Mrs Martin’s products, for that matter) and collect the water from your basin, you could store it for longer before using it in your garden. The beneficial microbes in the soap will retard the process in which pathogenic or ‘bad’ microbes multiply and make the water black. I invite you to try : we have several clients who say their systems stopped stinking after switching to our detergents!
You are not doing it to save money
Secondly, we will probably not be saving a lot of money. Good clean water is still cheap in South Africa.
A typical residential grey water system will save $5-$20 worth of freshwater a month, at best.
It could, however, make all the difference to your garden in a time of drought like we are experiencing now. If you are not allowed to irrigate your garden, using your grey water safely makes all the difference! Just don’t use it on your azaleas or hydrangeas as acid-loving plants don’t appreciate grey water.
The simpler the system, the better
Thirdly, the simpler the system the better. Art goes as far as to say that the moment a pump is involved you might have a net negative influence on the environment due to the cost of materials, manufacturing and electricity needed. He sees something as simple as a bucket as a grey water system.
Toilets can be flushed with grey water by simply bucketing it from the bathtub/shower directly into the toilet bowl (not the tank, where it will fester). An added plus of reusing bathtub water in this way is that due to flush volume always being under direct intelligent control it is always less. Also, in cold climates you get a primitive but highly effective sort of grey water heat recovery as the bath water sits there and heats the house as it cools.
It was after reading this last sentence that my efficiency instinct kicked in. I started to smile inwardly. Could it be that I could be heating my house this winter and gaining water for the garden AT THE SAME TIME?
Well, how I applied all my new-found knowledge, is for another post. Can’t wait to tell you!