What is graywater?

Graywater is any untreated household or building wastewater, with the exception of wastewater from toilets, dishwashers, and kitchen sinks. Essentially, graywater is the soapy water that comes from appliances and devices such as bathroom sinks, washing machines, showers, and bath tubs. The wastewater that comes from kitchen sinks, dishwaters and toilet on the other hand is referred to as blackwater. 

What is the benefit of using graywater?

The use of graywater reduces reliance on potable water for outdoor irrigation and minimizes the amount of water that enters our wastewater collection system. Graywater systems offer home and business owners an effective and environmentally friendly way to reuse their wastewater with minimal costs and effort. Graywater systems have the potential to preserve potable water sources for other uses, lower water utility bills, provide landscape irrigation, recharge groundwater, and reduce the strain on septic and sewer systems which can in turn lower energy loads at treatment plants. Utilizing graywater plays an important role in the effort to reduce, reuse, and recycle water.

Types of graywater systems:

There are three different classifications of graywater systems.  These three classifications vary in complexity, permitting requirements, and volume of water produced.  The most common, and widely used system uses wastewater from laundry to directly water a garden (gravity fed), this method does not require permitting of any type.  

1. Clothes Washer System: No permit required if in compliance with all items outlined in 1602.1.1 [HCD 1] of the California Plumbing Code: Chapter 16. Often described as "laundry-to-landscape", this system moves water from a single domestic clothes washing machines to gardens in a one- or two family dwelling. These types of systems require no plumbing alterations.  Please note: If a pump is used to move water, a permit will be required for this type of system.

2. Simple System: Permit required. Reuse water from bathroom sinks and showers in a one-and-two family dwelling, townhouse or other occupancy with discharge of 250 gallons (947 L) per day or less.  Often involve on-site plumbing alterations and include pumps and surge tanks.  

3. Complex System: Permit required.  Systems that discharge over 250 gallons (947 L) per day via a complex system of pumps, surge tanks, and filtration systems.  These systems are expensive to install and require large amounts of maintenance.

For more information about graywater standards and requirements please view California Plumbing Code: Chapter 16

Additional Links and Resources:

Greywater Action

Oasis Design