Plumber in Los Altos Hills, CA

A Homeowner’s Guide to Plumbing in Los Altos Hills

Water: Purissima Hills or Cal Water

The Town doesn’t run a water system. The Town’s housing element says Purissima Hills Water District (PHWD) serves about the northern two-thirds of Los Altos Hills and Cal Water the rest; a few residents also use well water. Your bill tells you which one you have.

• Purissima Hills Water District: (650) 948-1217, marked 24 hours on its website; office hours are weekdays 7 a.m. to 4 p.m. Customers repair leaks downstream of the meter, which sits underground near the street under a lid marked “WATER.” The house shutoff is usually below the hose bib at the front of the home. PHWD’s free EyeOnWater portal sends leak alerts to your phone.
• Cal Water, Los Altos Suburban district: (650) 917-0152, day and after hours. Cal Water is responsible only for the utility side of the meter; the plumbing on your side is yours. Its 2025 report says it has no known lead service lines.

On acre lots, the service line from the meter to the house can be long. If the meter dial keeps moving with everything off, the leak is between the meter and the house valve. See leak detection and water line replacement.

Sewer or septic

The housing element says about 40% of the Town uses septic systems; the rest is on public sewer, with flow carried through the City of Palo Alto’s or the City of Los Altos’s systems. For a backup or overflow, call Town Hall at (650) 941-7222 during office hours, or Santa Clara County Communications at (408) 299-3233 after hours.

Homes on septic are regulated by County Environmental Health, which issues permits for repairs, upgrades, emergency repairs and abandonment. The County doesn’t require an upgrade when you sell, but recommends pumping the tank every three to five years and having it evaluated for the sale disclosure. Under Town code, an existing home must connect to the sewer when a main is within 200 feet of the property line, unless its septic system is working to code; new homes and major additions within 200 feet must connect unless gravity flow isn’t possible.

Your lateral, all the way to the main

In Los Altos Hills, the homeowner owns the entire lateral, from the house to the sewer main, including the wye at the main and any part under the pathway, the asphalt or an easement (Municipal Code 6-4.443). If Town staff find the main isn’t the cause of a backup, you call a plumber; Town crews don’t work on private laterals. The Town recommends a backflow preventer and a cleanout on every lateral, and its standards call for 4-inch PVC laterals, one per lot.

A new connection takes engineered sewer drawings showing cleanouts and a backwater valve, a Town connection fee and review, an encroachment permit for work in the street, pathway or utility easement, and a building permit for the private side. Public Works inspects the public part and a building inspector the rest. Homes set below the street may need a sewage ejector pump. See sewer line replacement and trenchless sewer repair.

Hillside homes on acre lots

Los Altos Hills incorporated in 1956 with a one-acre minimum lot size. The housing element counts almost 40% of homes as built from 1960 to 1979, 19.1% from 1940 to 1959 and 4.9% before 1940, and notes that 20 to 25 homes are replaced each year. Homes from those decades can still have galvanized steel supply pipe, which rusts inside and loses pressure, and cast iron or clay drain lines that roots can enter. A camera inspection shows a long lateral’s condition before you buy or remodel. See repiping.

Permits for plumbing work

The Building Department (650-947-2501) takes most permits through eTRAKiT; small permits such as water heaters, furnaces and bathroom remodels can be emailed with a building application. Inspections are booked by phone three to four days ahead and aren’t held on Fridays. A water heater replacement needs a plumbing permit; the Town’s handout covers seismic straps, the relief valve drain, venting, combustion air and a sediment trap on the gas line.

The reach code requires all-electric new homes and detached ADUs, and Ordinance 611 (2024) applies zero-NOx requirements to new and substantially altered homes. Gas comes from PG&E: if you smell gas, leave and call 911, then PG&E at 1-800-743-5000. See gas line services.

Water heaters and rebates

PHWD’s Hetch Hetchy water averages 60 ppm hardness (8.1 to 112 ppm). Cal Water’s groundwater averages 305 ppm, and its Valley Water supply 97 ppm, so heaters on Cal Water scale faster. See water heater services. Compare other cities in our South Bay water hardness table.

The Air District’s zero-NOx standard for new water heaters is set for January 2027; a July 2026 draft would move it to January 2028, pending a Board vote. Silicon Valley Clean Energy offers Home Rebates for heat pump water heaters replacing gas or electric resistance units (reserve before installing; there’s a process for emergencies) and an Emergency Water Heater Replacement program through partner contractors. The Town also lists its own first-come rebate; ask the Building Department if funds remain. See SVCE Home Rebates and heat pump water heaters.

PHWD customers can use Valley Water’s landscape, irrigation equipment, graywater and rainwater capture rebates and free outdoor surveys. Cal Water lists conservation kits and fixture and irrigation rebates that vary by district.

Sources

Town of Los Altos Hills: Sanitary sewer · Homeowner responsibilities for sewer lateral · Procedure for sanitary sewer lateral connection (updated 10/1/26) · Sanitary sewer construction standards (2019) · Building Department · Water heater replacement handout · Reach codes · Building electrification · 2023–2031 Housing Element (October 2022 draft). Purissima Hills Water District: FAQs · Leak detection · Rebate programs · Contact · 2025 water quality report. Cal Water: Los Altos Suburban district · 2025 water quality report · Is Cal Water responsible for plumbing leaks? · Rebates and conservation programs. County of Santa Clara Environmental Health: Onsite wastewater treatment systems. Silicon Valley Clean Energy: Home Rebates · Emergency Water Heater Replacement. PG&E: Gas safety. Bay Area Air District: Draft water heater rule amendments (July 14, 2026). Checked October 2026.