Plumbing Brentwood

Plumbing in Brentwood, CA, where the tap blends wells and Delta water

Brentwood's tap water is a blend of the city's five wells and treated Delta water, and the two are far apart: in 2025 the wells averaged 363 ppm of hardness, the surface supply 75. Scale follows, but the usual fix is off the table, because since October 22, 2015 the city has banned brine-discharging, self-regenerating softeners to protect Marsh Creek. Under the street the news is better: the city maintains the lateral from the property-line cleanout to the main.

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  • Rules on this page checked against 13 public sources, October 2026
Water sources
Five city wells, plus Delta water bought from ECCID via the canal
Hardness, 2025 report
Wells 363 ppm on average; treated surface water 75 ppm
Softener rule
No brine-discharging softeners since October 22, 2015
Lower lateral
The city's, from the property-line cleanout to the main

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Free to request, and you agree the scope and price with the person you hire before work starts. In California, a job over $1,000 in labor and materials, or one that needs a building permit, must be done by a contractor licensed by the CSLB in the right class. Ask for the license number and check it at cslb.ca.gov.

The gateway arch into downtown Brentwood
The gateway arch into downtown Brentwood. Photo: LPS.1, CC0, via Wikimedia Commons.
Copper pipe fittings: elbows, a tee, reducers and couplings
Copper pipe fittings: elbows, a tee, reducers and couplings. Photo: Torsten Bätge, CC BY-SA 3.0, via Wikimedia Commons.

The houses here

Subdivision houses on acidic, pipe-eating ground

Most Brentwood houses went up in subdivisions from the 1990s and 2000s, and the city's standard conditions for residential design review called for raised wood floors, post-tension slabs or structural slabs, so on slab houses the drain lines run under concrete. The ground around them is its own problem. Brentwood's amendment to the plumbing code says high acid levels in both natural and imported soils across the city have proven highly corrosive to metallic pipe laid underground. The water itself is gentler on old pipe: the city's report credits its naturally hard groundwater with keeping lead and copper results well below action levels.

The work

What Brentwood plumbers are usually called for

  1. Treating hard water without a salt softener

    Water from the city's wells averaged 21.2 grains per gallon in 2025, against 4.4 for treated surface water, so the scale on fixtures and inside water heaters can be heavy. A conventional softener that regenerates itself and flushes salty brine down the drain cannot be installed. The city's fact sheet points owners to systems that send no chloride to the sewer, which reduce scale, soften, or both, and its building FAQ lists water softeners among installations that need a permit.

  2. Tankless water heaters and the gas line behind them

    Brentwood requires a permit to install or replace any water heater, and its tankless handout explains why the gas line gets attention: an on-demand heater needs much more gas flow than a tank, and existing piping may be too small. The application has to list the pipe material, size and run length and the heater's BTU rating. The handout also calls for a grounded outlet within six feet, with no extension cord, and bonding of the gas and water piping.

  3. Sewer backups at the property-line cleanout

    Every Brentwood lot needs an approved cleanout at or near the property line, and that cleanout is the dividing point. From it to the main, the city maintains the lateral, funded by a monthly lateral maintenance fee on residential owners. From the property line back to the house, repair and replacement are the owner's. Lateral work needs a written city permit, and a replaced lateral gets a backflow prevention device, kept clear of soil and landscaping.

  4. Buried gas lines to a pool heater or fire pit

    Because of the corrosive soils, Brentwood's plumbing code amendment bars metallic gas piping underground unless the chief building official approves it after a soils analysis shows a pH that will not corrode it. That leaves polyethylene, one of the materials the city's own permit forms list. The city's gas shutoff chapter also applies: when a plumbing permit is issued for gas piping, a seismic or excess-flow shutoff device is required, and an excess-flow system adds a device at each appliance.

Permits and local rules

City rules that change a Brentwood plumbing quote

  1. The ban on brine-discharging softeners

    Since October 22, 2015, Municipal Code 13.04.022 has barred installing a brine-discharging self-regenerating water softener. The reason is Marsh Creek, which receives the city's treated wastewater: the Central Valley Regional Water Quality Control Board's permit limits chloride in that effluent, the plant cannot meet the limit, and the city says most of the chloride in its wastewater comes from salt-based softeners. Alternatives must not discharge chloride to the sewer.

    City of Brentwood Water Operations Division (opens in a new tab)

  2. Where the owner's lateral ends

    The city's Public Works Department requires an approved cleanout at or close to the property line and states that the city is responsible for, and maintains, the lateral from that cleanout or property line to the main. All maintenance, repair and replacement from the property line back to the building belong to the owner. The same page notes that sewage from a plugged main is meant to overflow outside the house through a backflow prevention device, not inside it.

    City of Brentwood Public Works (opens in a new tab)

  3. What is in the water, source by source

    The 2025 Water Quality Report says groundwater from five city wells and surface water treated at the city's plant or the Contra Costa Water District's Randall-Bold plant reach the average customer as a blend. It lists the two sources separately, including hardness, sodium and nitrate. It also reports that the city's 2024 inventory found no lead, galvanized requiring replacement or unknown service lines, customer-owned lines included.

    City of Brentwood Water Operations Division (opens in a new tab)

State license for this work: C-36 Plumbing, C-42 Sanitation System. Look up a contractor's license on the CSLB website (opens in a new tab).

Before you hire

Points to settle before a Brentwood plumbing job

  • If a plumber suggests a water softener, ask whether it discharges brine to the drain; Brentwood does not allow one that does.
  • For a backup, ask the plumber to open the property-line cleanout first, since past that point the lateral is the city's to maintain.
  • If gas pipe will be buried, ask what material it is; metallic pipe underground needs the chief building official's approval.
  • If the slab has to be opened to reach a drain, ask how the plumber will locate post-tension cables before cutting.
  • Look up the C-36 Plumbing license at cslb.ca.gov, and confirm the permit is in the contractor's name.

Questions

Water and sewer questions Brentwood homeowners ask

Can I install a water softener in Brentwood?

Not one that regenerates itself and flushes salt brine into the sewer; those have been banned since October 22, 2015. The city's fact sheet describes alternatives that put no chloride into the sewer and may reduce scale, soften the water, or both. The building FAQ lists water softeners among installations that need a permit, so ask the installer to pull one.

Why is the water in Brentwood so hard?

Part of the supply comes from the city's wells, and in 2025 that groundwater averaged 363 ppm of hardness, about 21 grains per gallon. Treated surface water averaged 75 ppm. The average customer receives a blend of the two, so homes here see more scale than the surface water alone would leave.

Who pays to fix a sewer backup between my Brentwood house and the street?

It depends on where the blockage is. The city maintains the lower lateral, from the property-line cleanout to the main, as long as the lateral maintenance fee is paid. The pipe from the property line back to the house is the owner's to maintain, repair and replace, under a city permit.

Are there lead service lines in Brentwood?

The city reports none. Its 2024 inventory found no lead service lines, no galvanized lines requiring replacement and no lines of unknown material, and the report says that includes privately owned, customer-side lines. The report adds that lead in drinking water comes mainly from service lines and home plumbing.

Can our new barbecue gas line be run underground in steel pipe?

Not without approval. Brentwood's amendment to the plumbing code prohibits metallic gas piping underground unless the chief building official approves it and a soils analysis shows a pH that will not corrode it, because acidic soils in many parts of the city have eaten through buried metal pipe. Ask about polyethylene pipe, which the city's permit forms list, and plan on a permit.

Where these facts come from

Checked against these public sources in October 2026. Rules and programs change: confirm permit requirements with the city before work starts, and a contractor's license on the CSLB website.

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