Backwater Prevention Devices
- What is a BPD?
- What does a BPD look like?
- Do I need a BPD?
- Where are they installed?
- How do I maintain it?
A backwater prevention device (BPD) is installed on top of a sewer line cleanout access point. The device consists of a valve with a float that opens if the pipe fills with water and it also seals odors within the pipe. When blockages form in the sewer main or in a private sewer lateral, wastewater can back up in the pipe and flow toward a building or a nearby manhole. BPDs prevent sewage from backing up into a building and instead release the wastewater outside into the landscape.
If not already installed, the District requires that your private sewer lateral be equipped with an appropriate BPD (e.g., Contra Costa valve, as warranted by the individual site conditions). If properly installed and maintained, these devices help prevent sewer backup into your home or business. All BPDs shall comply with Ross Valley Sanitary District (RVSD) standards and shall be maintained by the property owner to provide for the continuing function as designed. For more information, please refer to the RVSD Approved Materials List.
Type I - "Mushroom" Type also known as "Contra Costa" Valve
Type 2 - Sewer Popper
BPDs are required on all new private laterals and lateral replacements. The owner or contractor should contact the District to obtain a sewer permit and arrange for a District Inspector to approve the installation of the backwater prevention device(s). The installation of any such BPD shall be at the sole cost and expense of the property owner.
BPDs should be installed on sewer laterals within two feet of where the pipe exits the foundation of a building and are sometimes located on a cleanout near the public sewer main.
If the BPD is below grade (Type 2) it should be enclosed in a suitable concrete utility box with a removable cover and shall be readily accessible for inspection and maintenance. It is critical that the top of a Type 2 BPD is installed at least six inches below the bottom of the box cover (see photo).
The maintenance of the BPD shall be the sole obligation of the owner, periodically checking that the device is clear of debris and functioning properly. All BPDs must be accessible and free from any obstructions, including, but not limited to: rocks, soil, vegetation, debris, grass, trees, bushes, plants, landscaping, concrete, asphalt or other ground coverings, or any other materials. Loose caps must not be buried, screwed down or clamped tight, or else they will not relieve the blockage. Regular maintenance will ensure the prevention of sewer backups inside a building.