Conveniently placed, next to the compost toilet at Eco-works, you'll find a pretty basic 'greywater' system. Also, recently made, somewhere nice to sit, and admire nature from.
Elements consist of a supported kitchen sink. The outflow, first filtrates through a vessel containing straw, for removing any larger particles. Then, below, another containing gravel. Ther is then an outflow pipe than then trickles water into an open channel, [resembling a water feature]. At the end of which is a small lagoon, contain a range of suitable plants, to finish the job. It can thus be returned to the ground.
Reusing Grey Water [CAT paper]
Grey water is the water from sinks, baths, the washing machine etc which has already been in contact with us humans and our germs, and reusing it for any purpose other than garden watering is difficult. It cannot be stored for any length of time without some fairly heavy duty treatment, as otherwise it will very quickly start to smell. Also, research into the impact of systems that treat grey water for reuse in the home have shown that the environmental impact of such systems (using chemicals and/or energy) usually far outweighs the benefits.
It's always best to first reduce the amount of grey water you produce, and there are many simple ways to achieve this. A shower should use much less water than a bath, and fitting spray-head taps and a low flow shower head can make a big difference to water consumption.
What greywater can I re-use?
Pollutants such as salt and grease in grey water can be damaging if it is used for irrigation. However, reducing the levels of these substances is fairly easy, and It is fairly easy to reduce the levels of pollutants (such as grease and chemicals) in greywater, enabling you to safely use it to directly to irrigate the garden. Water from the bath or shower is generally the easiest to re-use, as shampoos, soaps and so on are fairly mild and well diluted. Simple diversion kits are available which enable you to channel grey water from your downpipe into the garden.
If you want to re-use greywater from a washing machine on the garden, then do try and use detergent that is low in sodium, as it can damage plants and degrade soil. Also avoid phosphorus, which causes algal blooms if it collects in ponds or rivers. Otherwise, the water has very small quantities of other undesireables, such as pathgens or grease. Liquid detergents usually contain less salt than powders. Ex-kitchen water can be very dirty, and contain lots of undesireable things, like grease, oil, and chemicals. As it is generally produced in small quantities any, it's best not to reuse it.
Why not re-use it in the home?
Grey water contains bacteria and a nutrient source, and is often discharged warm, so you have an ideal situation for pathogens to multiply. Storing this water for re-use involves lots of treatment, and even then it will only be suitable for non-potable purposes such as toilet flushing.
Commercially available grey water recycling systems use disinfectants that are often very energy intensive to produce - and which may also cause problems if you have a private sewage treatment system. All independently published case studies of installed systems have shown running costs higher than that of mains water supply. Given the infrastructure requirements and the disinfectant doses needed, it is very difficult to see these systems as environmentally friendly, especially for individual households.
Grey water recycling is still a relatively young technology, and as such may improve with time, but shortages of water in the UK would have to become much more acute to justify domestic grey water systems. Advances in water treatment technologies may in future allow heavily contaminated water like grey water to be cleaned to suitable standards fairly cheaply - but the environmental impacts of this treatment might still be high.
A Handbook for Changing Our World
Edited by The Trapese Collective
Greywater reuse system (Water Dynamics) - Environment Agency
Photographer - Media: One Eye on the Road. Nottingham. UK
Member of the National Union of Journalists [No: 014345]
"It is not enough to curse the darkness.
It is also necessary to light a lamp!!"