Sewer Laterals

A key factor in solving sewer problems is the maintenance and repair of sewer laterals, the lines that run from each property to the sewer main. When laterals become cracked or damaged by tree roots, groundwater seeps into the sewer lines during wet weather. The system becomes overloaded and leads to sewer overflows and unpermitted discharges into the San Francisco Bay. It can also lead to sewer backups in residences. The town is proposing to inspect sewer laterals and assist property owners with repair or replacement, when needed.

If residents are having their laterals serviced to clear roots on a regular basis, they should consider having their lateral repaired or replaced. Several technologies exist where laterals can be lined with a non-corrosive material or injected with foam to prevent root intrusion. Call the Public Works Department at 650-375-7444 for more information about qualified plumbing contractors.

Inside a Lateral

This short video shows the interior of a lateral in Hillsborough that has been affected by root intrusion and, subsequently, ground water infiltration. Made in summer 2010, the video is stopped because of the break in the lateral pipe and ground water leaking into the sanitary sewer. This ground water infiltration occurs 24 hours a day, every day of the year. There was no sign above ground that this defect existed, and the resident's sewer lateral was not causing any backups at the home

Sewer Backflow Prevention
The Town of Hillsborough's Municipal Code requires certain homes to install sewer backflow prevention devices (also known as backwater valve) under certain conditions.  This device can prevent sewage from flowing into a home through toilets and drains due to a sewer main blockage.  Also, the Building and Planning Department has created a Backwater Valve Installation Guide which provides criteria for when a sewer backflow device is required by California Plumbing Code.