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Sewer Collection System


How can I help the Town maintain the system?
Residents can help by maintaining their sewer laterals and reducing water usage whenever possible, particularly during wet weather. Repairing or replacing a damaged sewer lateral reduces the amount of groundwater infiltration into the sewer system and prevents overflows.

How does the Town collect and treat our sewage?
Hillsborough's sewer collection system consists of more than 90 miles of sanitary sewer pipe.  It is known as a satellite system because the Town's wastewater is sent to treatment plants operated by the cities of Burlingame and San Mateo.

What are the consequences of a sewer overflow?
SSOs present not only a public health concern, but can compromise local waterways. When the downstream treatment plants become overloaded during heavy rains, it can lead to unpermitted discharges of wastewater into San Francisco Bay. Hillsborough and other communities in the Bay Area are working to maintain and upgrade their sewer laterals, mains and treatment plans to protect our water resources.

 A report on the Alternatives for Sanitary Sewer Capital Improvements was presented to the Hillsborough City Council in April. It can be viewed at the PDF Link below.

For more information about the town’s sewer system, visit:



More information is also available at http://www.sewersmart.org/

View PDF

What can I do to prevent sewer backups in the Town?
Proper disposal of all materials can help prevent backups and assist town crews in maintaining sewer lines. Residents can also maintain their sewer laterals and have them inspected periodically. If you plan to plant trees in your yard, make sure you know where your sewer lateral is located and avoid planting trees near a lateral. Roots are the most common cause of damage to laterals. The town will assist you in locating your sewer lateral.

What can I put in the toilet or drain?
Residents should avoid putting grease or eggshells in their sinks or garbage disposals. Grease is a major cause of sewer stoppages and eggshells do not decompose and can clog pipes and pumps. 

The only thing that should be flushed down the toilet is toilet paper. Other items, such as feminine hygiene products, wrappers, baby wipes and Swiffers can cause backups in sewer mains and laterals and damage sewer pumps.

What causes sewer line backups?
Sewer lines can back up when they become clogged with materials such as grease or paper products, or when tree roots damage mains and laterals and cause excess inflow into lines. Some backups occur during wet weather when sewer flows increase dramatically and lead to sanitary sewer overflows (SSOs) within the town’s collection system. A combination of increased flows and lack of downstream treatment capacity causes the SSOs.

What services does the Town provide?
The Public Works Department spends considerable time and resources maintaining the town’s sewer mains and trunk lines. The town provides free pop-up covers for residential sewer cleanouts that will permit sewage to flow out in the event of a blockage within your sewer lateral. Maintenance and repair of sewer laterals are the responsibility of the property owner.

Why does my sewer lateral require regular servicing?
A sewer lateral is the line that runs from a residence to the sewer main located in the street. In older residences, the lateral may be as old as the home itself and may require repair or replacement. If you have trees in the vicinity of your lateral, the roots may have damaged the lateral, causing backups. If you are required to have your sewer lateral serviced on a regular basis, it is an indication that it needs to be repaired or replaced. The Municipal Code requires that when a home is sold in Hillsborough, the sewer lateral be inspected and repaired or replaced if necessary. The town can provide a list of qualified contractors for inspection or repairs.

The Town of Hillsborough 1600 Floribunda Avenue, Hillsborough, CA 94010 (650) 375-7400
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