Can I legally discharge greywater on my property?

Local Regulations and Permits

Before discharging greywater on your property, it’s essential to check with your local authorities to determine if there are any specific regulations or permits required. In the United States, the Environmental Protection Agency (EPA) recommends that greywater systems be designed and installed according to the International Association of Plumbing and Mechanical Officials (IAPMO) guidelines. In many states, greywater reuse is regulated by the state’s water quality agency. For example, in California, greywater systems must be registered with the California Department of Public Health (CDPH). It’s also crucial to ensure that your local government allows greywater reuse for irrigation purposes.

Designing a Greywater Branched Drain System

A greywater branched drain system must be designed to separate greywater from blackwater and treat it to a safe level for reuse. The system typically includes a greywater tank, a treatment component (such as a septic tank or a sand filter), and a distribution network for irrigation. A good rule of thumb is to use a 2:1 or 3:1 tank-to-house ratio, where 1 house has 2-3 tanks to collect greywater. For example, a 1,000-gallon tank can serve a 1-bedroom home. The treatment component should be designed to remove pollutants and pathogens from the greywater. A sand filter or a septic tank with a pump and aeration system can be effective treatment options.

Treatment and Reuse

Greywater treatment should aim to remove pollutants and pathogens to a safe level for irrigation. Common treatment methods include sand filtration, membrane bioreactors (MBRs), and ultraviolet (UV) disinfection. The treated greywater should be reused for irrigation purposes only, and not for drinking or cooking. According to the EPA, greywater reuse can save up to 50% of potable water used for irrigation. To ensure safe reuse, the treated greywater should be monitored regularly for pH, turbidity, and bacterial levels.