Water heater repair and replacement in San Rafael and Marin County
We repair and replace tank and tankless water heaters across Marin County and southern Sonoma County. A standard tank replacement is $2,800 to $3,200 installed, permit included, and most repairs run $100 to $800. Call with your address and what the heater is doing, and we'll tell you what the visit costs before we book. California C36 license #1090862.
- Plumbing in Marin County since 2017
- California C36 plumbing license #1090862
- 5.0 stars from 89 reviews, as of October 2026
What's included
Included in every water heater replacement
- Sizing for your household, not just matching whatever was there
- Permit pulled and inspection handled
- Removal, hauling and recycling of the old heater
- New water connections with a proper shutoff, and venting checked and corrected
- T&P valve and pan drain run up to five feet, plus earthquake strapping where code requires it
- A free water pressure check and a walkthrough on how to flush the tank yourself
Priced separately
- Mid tier upgrade, about $790: full port ball valve, braided no-burst connectors, expansion tank and longer parts and labor coverage
- Top tier upgrade, about $1,322: adds a second ball valve, a quick drain valve and the longest coverage term
- Moving the heater to a new spot, quoted and approved before we start
- Leaks, valves and fixtures elsewhere in the house, see plumbing repair
Price guide
| Job | Price |
|---|---|
| Diagnostic visit, inspection and quote | $69 |
| After hours and holidays, for real emergencies | Quoted when you call |
| Common repairs: thermocouple, T&P valve, thermostat, expansion tank or tank flush | $215 to $430 |
| Larger repairs: anode rod, pilot or burner assembly, heating elements | $430 to $550 |
| Gas control valve or full electric rebuild | $550 to $800 |
| Tank water heater, 40 or 50 gallon, gas or electric, installed | $2,800 to $3,200 |
| Tankless water heater, installed | $6,000 to $7,000 |
What moves the price: how hard the heater is to reach, and anything the current setup is missing that code now requires, like an expansion tank or drip pan. Every price is flat rate, so the number we quote is the number you pay. See the full price breakdown
How it works
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Call us
Give us your address and what the heater is doing. If it's leaking, we'll walk you through shutting off the water to the tank.
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We come out
A real leak gets a response any time. If it can safely wait, we'll say so and be there first thing in the morning instead.
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You get one price
We check the heater and your water pressure, tell you whether repair or replacement makes more sense, and quote a flat rate.
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We finish and test
Install or repair, permit and haul-away, then a full test and a quick lesson on flushing it so it lasts.
What our job records show
6 of 50
Water heater jobs since November 2025 that also needed a new thermal expansion tank.
High pressure in the house works on a water heater every day, and an expansion tank is what absorbs it. That's why we check your pressure for free on every visit. Replacing a heater on an over-pressurized system just means we'll be back.
Our 50 water heater jobs range from sediment flushes and anode rods to a Navien tankless pump replacement and full 50 gallon swaps, across 14 towns from Petaluma to Sausalito.
Who does the work
Glenn Lopes
Owner and C36 license holder. Started Big Island Plumbing in 2017 after five years as a carpenter and a six month UPC code course.
Tainan "Tai" Siqueira
Partner and field lead. Handles most of the water heater work in Marin. No one here works on commission.
Recent water heater reviews
Read all our reviews on GoogleWhere we service water heaters
San Anselmo
Mill Valley
Larkspur
Corte Madera
Fairfax
Woodacre
San Geronimo
Ross
Tiburon
Sausalito
Santa Rosa
We also service water heaters in Greenbrae, Kentfield, Cotati and the rest of Marin and southern Sonoma County. See all service areas
Questions we get asked
How much does a water heater replacement cost in Marin County?
A standard tank is $2,800 to $3,200 installed, depending on gas or electric and 40 or 50 gallons. Tankless runs $6,000 to $7,000. Both include the permit, installation and hauling off the old unit.
My water heater is leaking. Can you come today?
If water is actively coming out, yes, we respond to real emergencies any time. Shut off the cold water valve on top of the tank first. If it's a slow drip into the pan, we'll usually tell you it can wait until morning and save you the after-hours rate.
Should I repair it or replace it?
If the heater is under about eight years old and one part failed, repair almost always wins. If the tank itself is leaking or it's past twelve years, replace it. In between, it depends on the repair and how long you're staying in the house.
How long does a water heater last?
Ten to fifteen years for a tank that gets flushed every year, and about twenty for tankless. Skipping the yearly flush is the fastest way to cut that short. More on what shortens it
Are you licensed?
Yes. Big Island Plumbing holds California C36 plumbing contractor license #1090862. You can verify it on the Contractors State License Board site.
Why did my new water heater need an expansion tank?
Water expands when it heats, and in a closed system that pressure has nowhere to go. An expansion tank absorbs it. Without one, the heater and every fitting in the house take that strain on every heating cycle.
Can I buy my own water heater and have you install it?
We'd rather you didn't. Big box versions of the same model are often built differently, and we can stand behind our labor but not a part we didn't source. We install Bradford White tanks bought from a plumbing supply house.
Related services
Water heater leaking? Call (415) 209-8142
We answer true emergencies 24/7, and an owner does the work.