Using Dishwater to Water Plants: Which Greywater is Safe in the ...

Using Dishwater to Water Plants: Which Greywater is Safe in the Garden?
The next time you come up dry due to watering restrictions, consider using dishwater to keep your flowers and veggies from dying of thirst. The detergent residue in the water won’t hurt them; as you might recall, dish soap is often used as a base for natural pesticides, because it helps the mixture stick to the plants, isn’t toxic, and can be easily washed off later. Just make sure your dish soap does not contain boron or bleach. You can read more in the article below about boron compounds and chlorine and how they can hurt plants.
Now, one caveat here: dishwater is classified as a type of “greywater,” because it tends to be cloudy rather than clear. While it’s not considered sewage as such, in some areas, you’re required by law to dispose of greywater through a proper sewer system. Therefore, it’s a good idea to check your local regulations before dousing the daisies with dishwater.
Also, keep in mind that while dishwater is fine to use on your plants, not all greywater is created equal. If you’ve used water to wash poultry parts, for example, don’t use it to water anything you’ll later be eating, because of the risk of bacterial contamination. Bathwater, of course, is right out.
Comments
I do not disagree with NOT using water from a bathtub or from washing poultry, as examples, for watering food one might eat. EXCEPT for fruit and other trees, and flower gardens. If fruit trees are properly pruned, there should be no danger of fruit contamination. This is especially true in climates where heat and sun are going to sterilize ground surfaces. It infuriates me that towns and cities pour ‘grey water’ back into our rivers and then complain about trees being an inconvenience to water and manage. As a former forester from Northwestern Ontario, where fire incidence IS increasing with global warming AND a former town councillor from that area (Nipigon, Ontario), it was bothersome to me that no one had the initiative to encourage separation of sewage so that grey water would maintain a healthy green perimeter around towns which were becoming increasingly worried about fire incursion. Alberta’s Fort McMurray wildfire devastation (and California, etc.’s growing problems) raise my ire when it comes to water, climate management personal responsible use of water and maintaining healthy trees where we are able. Don MacAlpine, former forester, Nipigon, Ontario, now in Regina, Sk. CANADA
Hello – Thanks for your thoughtful comments. I live in Sonoma County, California and we have lived through multiple years of devastating fires. Many of us attribute a good portion of that to climate issues, and a lot of it to urban interface and forestry management. Our community has used grey water for decades: for vineyards, silage crops, public landscaping, even regenerating thermal wells for generating electricity. The efforts are built from public – private planning and investment in the necessary secondary distribution and storage system. We are a dry county – only two rivers, and small streams and limited annual rainfall. But we are doing our best to use the water resources available – twice.