San Mateo County will require water tests every three months at small systems serving farmworker housing

Picture a farmworker family on the San Mateo County coast, living in a unit their employer provides, drinking from a well that serves three or four homes. Until now no agency tested that water on a schedule. State drinking water rules generally start at five service connections, so for a system that small, county enforcement was largely limited to responding to reports of a problem serious enough to count as an imminent health hazard.

When the county did test, it found trouble. After the January 23, 2023, shootings at two Coastside farms, which killed seven farmworkers, county departments formed the Farmworker Housing Compliance Task Force to inspect housing on agricultural and ranch land. It sampled 38 water systems serving farmworker housing that were not already subject to regular testing under state law. Twenty-one of them, 55 percent, tested positive for coliform or E. coli bacteria, the county's staff report says. The county says corrective action was taken at every one and follow-up tests confirmed safe water.

On October 20 the Board of Supervisors turned that one-time effort into a standing requirement.

"After the tragedy in January 2023, we made a promise that every farmworker on the Coastside would live in a safe and healthy home. The Task Force showed us that unsafe drinking water was the most common problem these families faced," Supervisor Ray Mueller, whose district includes the coast, said in the county's announcement.

What the board adopted

Two actions, both on October 20:

• The ordinance (Ordinance 4929). It repeals and replaces Chapter 4.64 of the county code, the water supply ordinance last updated in 1977, with a new Domestic Water Systems chapter. It was introduced on October 6 on a 5-0 vote (moved by Supervisor Mueller, seconded by Supervisor Lisa Gauthier) and adopted on the October 20 consent agenda, 5-0. It takes effect 30 days after adoption, which the county gives as November 19, 2026. The board adopted a companion rewrite of the county's wells ordinance (Chapter 4.68) the same day.
• The fee (Resolution 082170). After a public hearing, the board set an annual permit fee of $1,706 for each farm labor housing water system. The vote was 3-0, with Supervisors Noelia Corzo and David J. Canepa recorded absent.

What the ordinance requires

The new chapter creates a category called a Farm Labor Housing Water System: a piped drinking water system with one to four service connections, at least one of which serves a farm labor housing unit. For those systems the ordinance requires:

• An annual permit. No one may operate one without a county permit, renewed every year.
• Testing every three months. The operator must have at least one sample tested for total coliform and E. coli bacteria at least once every three months, by a state-certified lab, and send the results to the county by the tenth of the following month. The county can require more frequent testing for higher-risk sources, such as springs or wells under the influence of surface water.
• A fast retest. If a routine sample comes back positive, the operator must tell the county and take a repeat sample within 48 hours. If that one is also positive, the operator must fix the cause and notify everyone on the system.
• Testing after trouble. Extra samples are required after events such as a suspected waterborne illness, repairs to the well or pipes, or a pressure drop below 5 pounds per square inch.
• Standards and inspections. Systems must meet water quality, quantity and pressure standards, and county inspectors may enter, sample and inspect them unannounced during business hours.
• A notice to residents. Operators must tell the people they serve, once a year or by a posted notice, that the system is regulated less extensively than larger public systems and whom to call with questions.
• Owners stay responsible. Where a system serves tenants, the operator and the owner of the water source are both responsible for meeting the water quality rules, and the owner and operator must remedy any imminent hazard, including hazards to tenants.

Environmental Health Services can issue administrative fines of $100 for a first violation, $200 for a second within a year and $500 for each further one, with each day counted separately. In a lawsuit the county can seek a civil penalty of up to $5,000 a day per violation, and violations can be prosecuted as infractions or misdemeanors.

What it costs, and who pays

The permit fee is $1,706 a year per system, set to recover the county's cost. The county's Environmental Health Services division says its inspection programs are meant to be fully fee-supported. But the county will subsidize the fee while the program starts:

The fee was cut during outreach. The staff report says an earlier proposal would have cost $2,296 a year, with an on-site inspection every three years and one self-collected bacteria sample a year. After outreach to farm groups, a county agricultural advisory body and a Pescadero community council in October 2025 and August 2026, the county moved to an inspection every five years and four self-collected samples a year, at a lower fee. Operators also pay for their own lab tests, which the ordinance puts "at its own expense." The ordinance also lets the county bill operators for inspection and enforcement costs at its hourly rates, and charges double the standard fee to anyone who starts operating a system without a permit.

What it covers, and what it leaves out

• Covered: the 32 water systems serving 49 farmworker housing units in unincorporated San Mateo County that the county says the program will reach. The task force counted 124 active agricultural and ranch operations in the unincorporated area, 56 of which provide 145 farmworker housing units for an estimated 356 farmworkers.
• Larger systems stay where they were. Systems with 15 or more connections remain with the State Water Resources Control Board; systems with 5 to 14 connections remain with the county. The new chapter updates the county's rules for systems up to 14 connections.
• Other small systems are not on the testing schedule. A one-to-four-connection system that serves no farm labor housing (a "Local Water System") needs a one-time permit, and regular testing is encouraged but not required, unless it supplies a food facility. Those that do must test for bacteria every three months and for nitrates and nitrites once a year.
• Other small rental housing is not covered by the new program. The county says Environmental Health Services will keep testing similar-sized systems serving other multifamily housing when it receives complaints, as resources allow, and may consider expanding regular oversight if that testing finds comparable problems.
• Where it reaches. The county's figures, 32 systems and 49 units, are for unincorporated San Mateo County, where the task force worked. The ordinance text does not say whether its farm labor housing rules also reach systems inside cities.

Who it touches

• Farmworkers and their families living in employer-provided housing on small systems, who gain scheduled testing, notice from the operator if a positive sample is confirmed on retest, and a yearly or posted notice naming whom to call.
• Farm and ranch operators who house workers, many of them small family businesses, the county says. They take on an annual permit, quarterly lab tests, reporting and inspections, with the county paying all or part of the permit fee through June 2030.
• Food businesses served by small water systems of one to four connections that serve no farm labor housing, which now must test for bacteria every three months and for nitrates and nitrites once a year.
• Property owners who rent out homes on small systems, whose responsibility for water quality is now written into the code.

"Our staff will work with each operator, step by step, to bring their water systems into compliance," Charles Ice, director of Environmental Health Services, said in the county's announcement.

What happens next

• November 19, 2026: the ordinance takes effect, according to the county.
• Permits: operators apply to Environmental Health Services. Each permit includes a sampling plan that sets where, and at what time of year, the quarterly samples are taken.
• The subsidy steps down on July 1, 2027, July 1, 2029 and July 1, 2030, per the schedule above.

How to weigh in or get help

• Questions about the program: San Mateo County Environmental Health Services, 650-372-6200.
• The Board of Supervisors takes written comments at boardfeedback@smcgov.org; those received by 5:00 p.m. the day before a meeting go to the supervisors in advance, and later ones received before the meeting ends join the record. Name the agenda item. Spoken comments are heard in the chambers at 500 County Center in Redwood City or on Zoom. The October 20 agenda offered live Spanish interpretation of the whole meeting.
• Read the record: the ordinance, the fee resolution and the staff reports are linked in the sources below.