Quick Answer
A branched drain system for greywater should have 3-5 outlets to allow for efficient collection and distribution of wastewater from sinks, showers, and washing machines.
Designing a Branched Drain System
When designing a branched drain system for greywater, it’s essential to consider the number of outlets. Typically, a system with 3-5 outlets is sufficient for a standard household. However, this may vary depending on the number of appliances and fixtures connected to the system. For example, a system with multiple washing machines or a large commercial kitchen may require more outlets.
Outlet Placement and Sizing
The placement and sizing of outlets are critical in a branched drain system. Outlets should be located at least 6 inches off the ground to prevent backflow and should be sized according to the flow rate of the greywater source. A general rule of thumb is to size outlets to handle 2-3 gallons per minute (gpm) per outlet. For example, a showerhead with a flow rate of 2.5 gpm would require an outlet with a minimum size of 1.25 square inches.
Common Applications and Considerations
Branched drain systems are commonly used in residential and commercial applications where greywater is generated from sinks, showers, and washing machines. When designing a system, consider the local plumbing codes and regulations, as well as the desired level of treatment and reuse. For example, a system designed for irrigation may require more outlets and treatment steps than one designed for flushing toilets.
Find more answers
Browse the full Q&A library by topic, or jump back to the topic this question belongs to.