The Burlingame, Hillsborough, and San Mateo Sewer Lateral Tests

Raziel Ungar

Raziel Ungar

April 7th, 2020 - 4 min read


  • Sewer laterals are pipes that connect private homes to city-owned mains.

  • Several Peninsula cities (Burlingame, Hillsborough, Millbrae, Pacifica, South San Francisco, and San Mateo) have laws requiring sellers to pass a sewer lateral inspection before their home can close escrow.

  • One city, San Mateo, has a new program offering 50 percent grants for sewer lateral repair and replacement.

  • Methodology requirements differ from city to city, with only Hillsborough requiring video testing.

  • Sellers must absorb the costs of testing, which can range from an estimated $300 to $750.

  • Approximately 50 percent of homes tested in Burlingame since 1986 have required repair or replacement, at a cost ranging from $1,500 to $10,000

It’s not as sexy as, say, “red-hot real estate market,” but the term “sewer lateral testing” has recently gained plenty of traction on the Peninsula. No fewer than six San Mateo County cities – South San Francisco, San Mateo, Pacifica, Millbrae, Burlingame, and Hillsborough – require sewer lateral testing before signing off on the sale of a home. (San Carlos requires testing only if a property is being converted from commercial to residential use or is undergoing a major remodel.) San Mateo which recently passed an ordinance to require a passing test as of Dec 1, 2020, is now offering grants to help homeowners pay to test, repair or replace their aged sewer laterals, minus the point-of-sale requirement.

Burlingame Sewer Lateral Test


Sewer laterals are pipes connecting private homes to city sewer mains. They’re sunk underground and sit in place indefinitely – unless they spring leaks, in which case they are repaired or replaced. Cities’ challenge is to assure that these pipes aren’t leaking and leeching sewage into the ground. It’s in everyone’s best interest to see that sewer laterals are without leaks, cracks or tears; five Peninsula cities have decided the best way to do this is to make sewer lateral inspection a point-of-sale requirement – to be paid for by the seller. One has decided that the best way is to aid homeowners in getting their sewer laterals ship-shape now, rather than wait until point-of-sale.

Point-of-sale requirements have been somewhat controversial. In the spring of 2014, the City of Belmont tried to introduce legislation requiring point-of-sale sewer lateral inspections but succeeded only in drawing pushback from homeowners and Realtors who argued that a citywide program, paid for by the city and not dependent on point-of-sale, would be a better system for all. In the end, Belmont made sewer lateral testing a necessary disclosure for listing agents. In Pacifica, where point-of-sale inspections were mandated in 2012, some residents have taken to local news message boards to express their displeasure.

Nevertheless, sewer lateral inspections are gaining popularity among cities with an inventory of aging single-family housing (and sewage systems). South San Francisco, Pacifica, Millbrae, Burlingame and Hillsborough all require that sellers hire (at a cost ranging, according to each city’s estimate, from $300 to $ 1,000) a licensed contractor to inspect their sewer lateral. If test results show a leak or leaks, homeowners are required to repair or – in extreme cases – replace their line, at a cost ranging from $1,500 to $10,000. Only when a sewer lateral is given a clean bill of health can escrow close.

In Burlingame (as well as in South City and Pacifica), homeowners are subjected to testing using water pressure instead of smoke. Again, the concept is simple: using a balloon, testers wall off a section of pipe, then flood it with four gallons of water, wait 30 minutes and re-check the water level. If it’s fallen below four gallons, there is a leak.

Burlingame also employs air pressure testing, in which air is pumped into pipes until its pounds per square inch (PSI) reaches 4.0. After a two-minute period, it should take more than 10 seconds to drop the pressure inside the lateral from 3.5 to 2.5 PSI. If the pipe is breached, the pressure will drop more quickly.

Hillsborough, which adopted its Sewer Lateral Ordinance in 2012, requires that sellers snake a small video camera into the lateral connecting to the sewer main – unless: “a sewer lateral connects with the sewer main in a street right-of-way.” In this case, a water test, reaching from the “building structure” and the property line will do. Millbrae also requires a visual test. San Carlos, when it does require a test, also insists on video. San Mateo, which does not have a testing requirement, does not specify an “acceptable” testing methodology.

Since Burlingame enacted its law, in 1986 (it was amended in 2000), approximately 50 percent of homes tested have required sewer lateral repair or replacement, with individual homeowners footing the bill. So this is no trifling thing.

In San Mateo, effective Dec. 1, 2020, the revised private sewer lateral ordinance has four triggers that require a property to conduct a sewer lateral inspection:

  • Sale of real property

  • Improvements to property that are greater than or equal to $90,000

  • Sewer class change as defined by section 3.54.020

  • Sewer lateral backup or blockage resulting in a sanitary sewer overflow for commercial or multifamily residential buildings

If any of the four triggers listed above apply to your property, then a sewer lateral inspection is needed. The Private Sewer Lateral Cost Sharing Program was created, according to the City of San Mateo website, to “assist and encourage property owners to properly maintain their lateral and ultimately reduce the amount of inflow and infiltration into the city’s sewer system.” It offers grants to cover up to 50 percent of homeowners’ lateral cleanout, repair, and replacement costs, up to $5,000. The program opened on July 1, 2014, and lasts until June 2015. All homeowners are eligible on a first-come, first-serve basis.

This program is not new. Once called the Healthy Home Program, it was test-run in 2009-2010 as a combination grant and loan program, initially targeting the San Mateo Village area; unfortunately, Healthy Home ran out of funds in 2011. Now, a version of it is back. South San Francisco also piloted a version of this program in 2012-2013, offering up to $2,500 in matching grants. That’s it for San Mateo County. A search turned up only one other similar program, in Modesto.

There’s more than one way to inspect a sewer lateral, and the six Peninsula cities requiring point-of-sale testing do not share methodology. There are several ways to skin the sewer lateral cat, as it turns out.

Belmont’s proposed program employed something called “smoke testing.” Though the term might strike fear into the hearts of fans of the TV show “Lost,” smoke testing is relatively benign. Smoke is blown into sections of pipes; if any escapes, we’ve got a problem. The City of Berkeley presently has a comprehensive smoke testing program that includes both laterals and mains – paid for by the city, not at point-of-sale.

There are exemptions. In Burlingame, a property is exempt if it has passed inspection within the past decade. If it hasn’t, there’s still good news: properties whose lines have been replaced are exempt for 25 years. Homes located less than six feet from the city’s right-of-way may be exempt and all condominiums are exempt. For everyone else in these six cities, sewer lateral testing is a necessary – and potentially costly — fact of selling your home. For those in San Mateo, though, sewer lateral testing method and whether it passes or not is up to the plumber the seller hires.


The Hillsborough Sewer Lateral Test

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