BPU Explains the Difference between Backwater Valves & Backflow Prevention Devices


Article Contributed by
Jamestown Board of Public Utilities

BPU water and wastewater/sewer customers should know the difference between backwater valves and backflow prevention devices and when the equipment is needed in a home or commercial/manufacturing setting.

Wastewater/Sewer: Backwater Valves

Property owners are responsible to prevent wastewater (sewage) from backing up into their buildings.

A backwater valve is a device installed to decrease the risk of wastewater backup into a building. The valve is a simple mechanical device that closes when sewer water flows back against it. For residential buildings, it is installed where the underground sewer lateral connects to a home. In BPU territory, the installation of a backwater valve is required to be done by a Master Plumber licensed in Jamestown.

Having a backwater valve installed will offer moderate protection for a property owner if the valve is properly installed and regularly maintained. The only absolute protection against wastewater back up is to ensure that the lowest sewer drain opening on your property is higher than the elevation of the nearest upstream wastewater manhole, in or near the street, per New York State code 714.1.

Only wastewater is permitted to be drained into the sanitary sewer system. There is a separate storm drain system that is designed to handle the influx of water flow during a rainstorm. Eliminating connections that route ground and storm water into the sanitary sewer system reduces the overall risk of overwhelming it, leading to fewer backup events.

Drinking Water/Backflow Prevention Device

In New York State, all commercial/industrial properties, multi-family dwellings, new residential properties and remodels are required to have backflow prevention devices installed. This is a New York State requirement and is for the protection of the entire public water supply.

A water backflow prevention device is a valve connected to a water service which prevents potentially contaminated water from flowing backwards through a private property’s pipes into the public water supply. Such an event could contaminate the supply of water to other properties.

Backflow prevention devices must be installed by a licensed plumbing contractor. Most backflow prevention devices require annual testing to check their functionality while others do not. To determine the appropriate device, the plumbing contractor will do an evaluation based on the property type and potential backflow risk and submit their recommendation to the BPU and the Plumbing Inspector for approval before the installation. (For example, a single-family home with a swimming pool or lake front location will require a different type of device than a home without a pool or lake front location.)

In Summary

Backwater valves offer moderate protection against wastewater backups but removing any drain openings below the elevation of the nearest upstream manhole lid is the most effective and complete prevention. It is the property owner’s responsibility to prevent wastewater from backing up into their buildings. Backflow prevention devices protect the potable (drinking) water supply. It is everyone’s responsibility to protect the public water supply.


Questions regarding backwater valves for wastewater/sewer issues or drinking water/backflow prevention devices may be directed to the Water Department at (716)661-1688 or Communications at (716)661-1680.