Infiltration and Inflow

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What is Infiltration?

Infiltration is when groundwater enters the sanitary sewer through defective, broken or offset pipes. What causes these issues is that throughout the years, ground movement and roots can caused these pipes to become offset or damaged.  If water can get in then so can roots, which will grow into a mass that will eventually block the line. A blockage in a sewer lateral can lead to private lateral sewer discharges (PLSDs), which the city is required to report to California State Water Resources Control Board. Property owners are the responsible party for a (PLSD), along with the cost of the cleanup and any fines associated with the discharge.
Infiltration is also the leading cause of sinkholes by drawing in dirt along with ground water into a break or offset in the sewer pipe.  Overtime this process creates a void around the pipe and at some point; will collapse on its own or with the help of the weight of a person or vehicle.

lateralinfil  lateralRoots  sinkhole

What is Inflow?

Inflow is the introduction of stormwater into the sanitary sewer system by property owner’s inappropriate connections to their sewer lateral. These connections usually are sump pumps, roof drains, and yard drains, but have also been found to be yard and gutter drains, draining to the top of a manhole in backyard easement.  Inflow is the leading cause of Sanitary Sewer Overflows (SSOs) and for the continue increase in sewer fees along with potential health problems.  Belmont Code Chapter 21, Sec. 21-152 specifically addresses these unlawful connections.



  Infiltration and Inflow Brochure

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