Publication Date

Summer 2021

Degree Type


Degree Name

Master of Science (MS)


Environmental Studies


Katherine Kao Cushing


Code compliant systems, drought, Fecal Coliform, Laundry to Landscape greywater systems, Soil quality, Wastewater reuse

Subject Areas

Water resources management; Soil sciences; Environmental science


Many communities worldwide are facing water shortages and droughts, stressing the critical need for water conservation. Following the longest recent drought cycle in California (2011–2017), local water companies are prioritizing the development of unconventional water sources, such as laundry-to-landscape greywater, which is a low-tech method to reuse water. This study describes the characteristics and performance of installed greywater systems in San José, California, including the systems’ conformance with California plumbing codes and landscape plants irrigated by the systems. Over three-quarters of the greywater systems conformed to the California Plumbing Code, and nearly 60% of the landscapes were drought-tolerant. Samples of both greywater and soil from 31 households showed that water quality, besides iron and calcium, was mostly in the acceptable range for wastewater-reuse irrigation, and values of many of the parameters were lower than previously reported. Code-compliant systems performed better than non-code-compliant systems for fecal coliform and nitrate, as well as for calcium, magnesium, potassium, organic matter, organic carbon, cation exchange capacity and boron, but even systems that did not adhere to the codes did function for water conservation. There was accumulation of salt and nutrients for older systems in soil. The results of this study strengthen the reuse of these systems as an attractive solution in conserving water.