Using Grey Water to Irrigate Plants
(Grand Forks, B.C.)
Soap Bubbles - where can I use grey water?
Grey water is water that you've already used in everyday household operations - laundry, showers, or washing the floor. Sometimes, this will contain soap residue, and even other things too, such as bleach.
Many experts recommend not using this kind of water on edible plants, for a couple of reasons. First and most important, it will quite often contain a lot of potassium which is one of the ingredients of soap. It has an effect on soil, such as killing off all the micro herd, which is a no-no, if you've been paying attention.
Other issues are that if you're watering succulents, the soapy film will cling to the leaves, just like on the shower stall.
For these reasons, I wouldn't use soapy grey water directly on any plants that you really like. Lawns are a good place to use grey water. Rinse water, if it's possible to isolate the water from washing clothes is fine to use on all plants.
So what can you do, especially in droughts? Well, one way that a lot of people in Australia and other areas utilize grey water is to water a mulch bed, which is a large prepared bed with gravel for a base, planted with reeds or even willows. Then once the plants reach a good size, they are cut down and used for mulching, or to make compost.
Tip for grey water; don't try to save this for later use. It will smell abominably bad. Use it immediately, and let the ground use it.