Rainwater Harvesting Regulations — Do They Apply To Diverters?

Regulations and Diverters

In the United States, the National Association of Home Builders (NAHB) and the International Association of Plumbing and Mechanical Officials (IAPMO) provide guidelines for rainwater harvesting. While these organizations do not mandate specific regulations, local authorities may adopt and enforce their standards. For example, the City of Seattle’s rainwater harvesting ordinance requires diverters to be installed according to the International Plumbing Code (IPC) and the International Residential Code (IRC).

First Flush and Diverters

A first flush device is a critical component of a rainwater harvesting system that prevents contaminants and debris from entering the storage tank. When selecting a diverter, property owners should consider the type of first flush device to be used. A 1:10 to 1:20 ratio is a common guideline for the diverter’s opening size and the roof drain’s diameter to ensure efficient first flush operation. By selecting a suitable diverter, property owners can ensure the quality and safety of their harvested rainwater.

Local Ordinances and Compliance

Property owners should familiarize themselves with local regulations regarding rainwater harvesting systems, including diverters. To ensure compliance, it is essential to obtain necessary permits and inspections from local authorities. For example, the State of California requires rainwater harvesting systems to be inspected and permitted by local building departments. By understanding and complying with local regulations, property owners can avoid fines, system shutdowns, and potential health risks associated with improper rainwater harvesting practices.