Green Plumbing-How to Use Plumbing to Water Your Plants

Here’s another Green Plumbing method on how to kill two birds with one stone. Do you have some plants that need to be watered, but you don’t want to waste water?

Greywater is gently used water from your bathroom sinks, showers, tubs, and washing machines. It is not water that has come into contact with feces, either from the toilet or from washing diapers.

Greywater may contain traces of dirt, food, grease, hair, and certain household cleaning products. While greywater may look “dirty,” it is a safe and even beneficial source of irrigation water in a yard. Keep in mind that if greywater is released into rivers, lakes, or estuaries, its nutrients become pollutants, but to plants, they are valuable fertilizer. Aside from the obvious benefits of saving water (and money on your water bill), reusing your greywater keeps it out of the sewer or septic system, thereby reducing the chance that it will pollute local water bodies. Reusing greywater for irrigation reconnects urban residents and our backyard gardens to the natural water cycle.

The easiest way to use greywater is to pipe it directly outside and use it to water ornamental plants or fruit trees. Greywater can also be used to irrigate vegetable plants as long as it doesn’t touch edible parts of the plants. In any greywater system, it is essential to use “plant friendly” products, those without salts, boron, or chlorine bleach. The build-up of salts and boron in the soil can damage plants. While you’re at it, watch out for your own health: “natural” body products often contain substances toxic to humans (see resource pages below for details).

We believe that for residential greywater systems simple designs are best. With simple systems you are not able to send greywater into an existing drip irrigation system, but must shape your landscape to allow water to infiltrate into the soil. We recommend simple, low-tech systems that use gravity when ever possible, instead of pumps. We prefer irrigation systems that are designed to avoid clogging, rather than relying on filters and drip irrigation.