Plumbing Help for San Marino Homeowners: Houses From the 1940s and Two Water Suppliers

By our sums from Census counts, about 41 percent of San Marino homes date from 1939 or earlier, about 82 percent from before 1960 and about 93 percent from before 1980. The same tables show no buildings of five or more units and roughly 83 percent owner occupancy, so most calls come from people who own a detached house and decide on the repair themselves.

A house that old can hold a mix of pipe materials from different decades of repairs, which is why a camera look is worth asking for before anyone quotes a replacement. The city's historic resources survey also describes many mature street trees. We found no San Marino source tying roots to sewer trouble, so treat roots as one possibility the camera can confirm or rule out. When more than one fixture drains slowly, see slow drain repair.

San Marino runs no water department of its own. The city's water page says California American Water or Sunnyslope Water Company serves you, depending on where you live, and we found no street map that settles which. Your bill shows the name, and that is the number to call about pressure, taste or a meter.

Cal Am's San Marino system takes about 90 percent of its supply from groundwater and about 10 percent from Metropolitan Water District. The newest Cal Am report we could read covers 2022 and 2023 and gives a hardness of 162 mg/L, about 9.5 grains per gallon, with sodium between 20 and 58 mg/L. Sunnyslope's 2025 report gives 130 mg/L hardness and 28 mg/L sodium. Water in that range can leave scale on heating elements and fixtures, and a tank water heater is usually where it shows first. Neither report says anything about softeners. Phone lines are (888) 237-1333 for Cal Am customer service and (626) 287-5238 for Sunnyslope.

The city operates its own sewer collection system, about 50 miles of pipe, and it connects to Los Angeles County Sanitation Districts trunk sewers. The city's sewer page says the city maintains the public main and property owners maintain their own lateral. For a backup you suspect is in the street, report it through Public Works at (626) 300-0765. A backup that only affects fixtures inside the house is the owner's side, and a plumber can run a camera to find out. See repairing a sewer lateral for what the options look like.

The city's new-resident manual adds a San Marino-specific point: some private sewer connections lack a backwater valve, and fixtures below the next upstream manhole need one. It says a permit and inspections are required to install it. Ask a plumber whether your lateral already has the valve before any sewer work begins.

The city's 2024 hazard mitigation plan describes the soil as mostly Ramona loam, which it calls permeable, and it says expansive soil is not a significant issue in San Marino. That rules out the clay-heave story behind pipe breaks in some other foothill cities. Liquefaction is mapped as medium to high only near the northeast city border. The Raymond Fault and part of the San Rafael Fault run through or near the city, and the plan notes that shaking can damage underground utilities.

The Housing Element names three places with short periods of localized flooding: Huntington Drive near Old Mill Road, Lacy Park, and Huntington Drive near the high school. If your lot is close to one of them, say so when you describe a drainage or leak problem. No source we found names the usual foundation type here, so expect the plumber to check yours; if you suspect a leak under a floor, see locating a slab leak.

The Building Division of Community Development, at 2200 Huntington Drive, issues plumbing permits, and the city page says some can be issued online. Its permit application has fee lines for tank, tankless and condensing water heaters and for house sewer repair including a cleanout. We found no line named repiping, so the page rule is simply that plumbing work needs a permit; the plumber should tell you which one applies. The application carries both a licensed-contractor declaration and an owner-builder declaration. For a replacement heater, see water heater swap.

Two other rules can slow digging. The new-resident manual defines a protected tree as at least 15 feet tall and at least 6 inches across at 4.5 feet, and it requires an arborist's tree protection plan for construction under the canopy. The municipal code limits construction hours to weekdays 7 AM to 6 PM and Saturdays 9 AM to 4 PM, with an exception for emergency repairs.

For a heater that makes noise, runs out of hot water early or leaks at a fitting, the first question is the supplier and the second is the tank's age. Water in that range builds scale gradually, so the tank's age is often the better guide. See pilot and thermostat repair for what is fixable and what is not.

Callers here also ask about toilet repair, garbage disposal replacement, gas line help, hidden-leak testing, repiping options, tankless water heater options, drying a flooded room, water line leak repair and reverse osmosis and filters. If the problem cannot wait, the dispatch line details explains the after-hours routing.