Leak Detection and Repair in Palo Alto, CA

A Homeowner’s Guide to Leak Detection and Repair in Palo Alto

Where CPAU’s pipe ends and yours begins

Palo Alto homes buy water from the City’s own utility, CPAU. Two of its rules decide who handles a leak.

Part of the system (CPAU rules as of October 2026)	Who maintains it
Water main in the street, up to and including the meter near the curb	CPAU (Rule 21)
Meter box or vault	The customer (Rule 21)
Yard line from the meter to the house, and all piping inside	The customer (Rule 21)
Water main break or service disruption	Call CPAU Utilities Dispatch, (650) 329-2579, any hour

Leaks waste water the City can act on: Rule 21 says that when CPAU finds water waste from leaking or defective equipment, it follows the steps in Municipal Code Section 12.32.010. A leak anywhere past the meter, whether in the yard, the walls or the slab, is the owner’s to find and fix. See leak detection and water line replacement.

How CPAU flags a leak

CPAU has been installing Advanced Metering Infrastructure (AMI) meters; Valley Water’s March 2026 table puts the rollout at 87% of about 21,400 meters. What you get depends on the meter:

• With AMI: single-family homes have received courtesy email alerts since October 2024 for continuous use of 5 gallons an hour for 24 hours, or 75 gallons an hour for 8 hours. WaterSmart, reached through MyCPAU, shows hourly, daily and weekly use, with possible leaks marked in orange.
• Without AMI: a billed-usage alert follows the bill when monthly use passes 750 gallons a day or tops the seasonal high of the past two years by 200%. The account needs two years of history.

Leak alerts can be turned off in MyCPAU’s communication preferences, so check they’re on. An alert tells you water is running, not where; that is the part we do.

The Rule 11 leak adjustment

Rule 11, effective July 1, 2026, is the City’s leak bill policy, and it is narrower than many homeowners expect:

1. Customers with an AMI meter aren’t eligible, since they can get alerts.
2. Others apply within 60 days of the due date of the bill covering the high use.
3. One request per 36 months, covering water, wastewater or both.
4. The leak must be repaired first. Turning off the source isn’t a repair, and high use with no identified cause isn’t eligible.
5. The adjustment applies to half of the volume above your three-year average, priced at the Tier 1 rate.

Eichler slabs: what the City’s guidelines say

Eichler Homes built some 2,700 houses in Palo Alto, in central and southern neighborhoods. The tract list in the City’s Eichler Neighborhood Design Guidelines starts with University Gardens (1949–1950) and runs through Greenmeadow No. 3 (1961–1962), with three small tracts added in the 1970s. Greenmeadow and Green Gables are National Register historic districts.

Section 5.5 of the guidelines is the part that matters for leaks. Plumbing and the original radiant heating were placed in the concrete slab and may be difficult to repair without highly invasive work. The guidelines ask owners to repair in place where feasible, note that the copper heating pipe in some Eichlers can be repaired without removing concrete while steel pipe is much harder to fix once corroded, and point to low-profile floor systems, or plumbing over the roof kept out of view from the street, when in-slab plumbing must be replaced.

That’s why we locate a slab leak precisely before anyone breaks concrete. See slab leak repair.

Permits, pressure and soft water

• Permits: a licensed contractor can get an instant permit to re-pipe the water system of a detached single-family home or duplex (interior only). Other standalone water system repairs can use the City’s over-the-counter MEP pilot. See repiping.
• Pressure: the Building Division’s repipe checklist (revised 2011) notes static pressure above 80 psi, typically west of El Camino Real, and calls for a regulator in that case. High pressure strains supply hoses, valves and old joints.
• Water quality: CPAU’s 2025 water quality report shows hardness averaging 62 ppm, soft for the South Bay, and no lead service lines in the City’s system.

Sources

City of Palo Alto Utilities: Rule 21, Special Water Utility Regulations (effective June 1, 2026) · Rule 11, Billing, Adjustments and Payment of Bills (effective July 1, 2026) · Utility Rules and Regulations · Manage Your Water Use With WaterSmart · Contact Utilities · 2025 water quality report. Planning and Development Services: Eichler Neighborhood Design Guidelines (2018) · Apply for a Building Permit · Over-the-Counter Residential MEP Permit Pilot Program · Repipe inspection checklist (rev. 2011). Valley Water: Understanding your water use (AMI status, March 2026). Checked October 2026.