Estimate how much graywater your plants need

Does your graywater production equal how much water your plants need? Pick the right amount of plants to irrigate based on your estimated graywater output.

Irrigation requirements depend on whether the plants being irrigated are water-intensive (e.g., fruit trees), drought-tolerant, or somewhere in the vast middle. Plants usually have an estimated water demand factor that can be found through online research or by contacting a local nursery. If you apply for the rebate, we'll help you estimate this.

On average, an older top-loading clothes washer produces enough water for an 800 square-foot area of trees, shrubs, and vines. For a rough estimate: 

• A front-loading clothes washer can provide water for 1 tree for every load per week and up to 8 outlets overall.

• A top-loading clothes washer can provide water for 2-3 trees for every load per week and up to 12 outlets overall.

To help calculate the amount of graywater needed to irrigate your plants, see Table 1 in this PDF from the University of California Division of Agriculture and Natural Resources.