Replacing a Water Heater

6.4.1 When is it time to replace?

No primary source read for this page gives a water heater lifespan in years, so this page doesn't name one. What the sources do say is that hard water costs equipment life: the USGS ties the scale left by heated hard water to shorter equipment life (USGS), and FPUD's 2025 data averaged 13.7 grains per gallon.

Many symptoms point to a part, not the whole heater. Rheem's manual ties an occasionally discharging relief valve to thermal expansion in a closed system (Rheem AP21831), and A. O. Smith's manual says a valve that won't reseat needs replacing, not the tank. A leak from the tank body itself is different; neither manual offers an owner fix for that. A licensed plumber can tell a failed tank from a failed fitting. The relief valve page §6.2 covers the drip question in more depth.

6.4.2 Does replacement need a permit?

It depends on who governs your parcel. For the unincorporated County, form PDS 110 (rev. 1/1/2026) lists among work exempt from a plumbing permit "a replacement water heater with no change to the unit type or servicing utilities when performed by a California licensed plumbing contractor" (San Diego County PDS 110). The same form treats replacing defective concealed pipe as new work that needs a permit and inspection.

The City of Escondido takes the stricter line. Its residential water heater handout quotes the plumbing code rule that installing, removing or replacing any water heater without first obtaining a permit is unlawful (Escondido handout). Vista is also a city with its own building department; no Vista rule was read for this page, so check with the City of Vista.

A mailing address is not always the jurisdiction: some homes with an Escondido or Vista address sit outside city limits. If in doubt, confirm with the County or city before the old heater comes out. And note what the County exemption leaves out: a change of unit type or of the servicing utilities.

6.4.3 Tank or tankless in hard water?

Both heat water, and heated hard water is what leaves scale behind. Rheem's tank manual expects deposits in anything harder than 5 grains, building quicker as the setting rises; A. O. Smith recommends, where water is hard, water softening or threshold-type treatment (A. O. Smith 324257). No tankless maker's manual was read for this page, so ask any installer for the model's own descaling interval and water-quality limits in writing.

The permit question changes too. Switching from a tank to a tankless unit is a change of unit type, which falls outside the County's like-for-like exemption, and it can change the gas connection, venting and electrical service. Plan on a permit in the unincorporated County as well as in Escondido. See scale and flushing §6.1 for the maintenance side.

6.4.4 What gets checked at install?

A good install covers safety items that are easy to verify afterward:

Items to look for on a new heater

Strapping

Restraints in the upper third and lower third, the lower one at least 4 inches above the controls, anchored to wall studs per SDG&E. Details on the earthquake straps page §6.3.

Garage height

A gas heater in a garage with its ignition source at least 18 inches above the floor, unless it is an FVIR unit that may be exempt (SDG&E).

Expansion control

An expansion tank wherever a regulator, check valve or backflow preventer closes the system, per California Plumbing Code §608.2-608.3 and A. O. Smith. See thermal expansion tanks §3.3.

Relief valve and discharge pipe

A new T&P valve with an open, uncapped discharge pipe running down and away from where people stand.

Thermostat

Set near 120°F, the starting point A. O. Smith, DOE and SDG&E name.

A. O. Smith's manual also says the gas stays off until the tank has filled completely, one reason the first fire-up belongs to the installer. Gas piping, venting, the burner and the relief valve are jobs for a licensed installer. If you're unsure, call a licensed plumber.

If anyone smells gas or hears hissing around the new heater, the steps don't change: leave the house first, avoid switching anything on or off or using anything that could spark inside, and, once outdoors, call 911 or the SDG&E gas emergency line (SDG&E gas leaks).

6.4.5 What should a quote include?

A written quote should name the heater, the permit plan, and the safety items above. The CSLB rules give a homeowner several checks on the paperwork (CSLB contracts guide):

• A license number, which ads must also show, and a current status on cslb.ca.gov. Plumbing contractors hold the C-36 classification.
• A licensed contractor whenever the job reaches $1,000 for labor and materials together, or needs a permit.
• A down payment no higher than 10% of the price or $1,000, whichever is less.
• Three business days to cancel a home-improvement contract, five if the buyer is 65 or older; a service-and-repair contract waives that right.
• Workers' compensation coverage if the contractor has employees, and a $25,000 license bond on file.

Ask also who pulls any permit, whether strapping and expansion control are included, and what happens to the old tank. Current tank and tankless models can be compared at water heaters (PlumbingSupplyAndMore, owned by the people who run North County Water & Pipes) before talking to an installer. More on vetting is on choosing a plumber §4.5.

6.4.6 Common questions

Q. Does a Fallbrook water heater swap need a County inspection?

Not if it is like-for-like and done by a licensed plumbing contractor; PDS 110 exempts that from a plumbing permit. A change of unit type or servicing utilities falls outside the exemption.

Q. Who pulls the permit for an Escondido replacement?

Escondido's handout says a permit is needed before the work starts but leaves the logistics to you and the installer. Put who pulls it, and who meets the inspector, in the written quote.

Q. Can a homeowner replace a water heater in the unincorporated County without a permit?

The PDS 110 exemption is written for work performed by a California licensed plumbing contractor. An owner doing the work is not what that line describes, so ask the County first.

Q. Does switching from gas to a heat pump heater change the permit?

A different unit type and different servicing utilities fall outside the County's like-for-like exemption. Expect a permit, and in Escondido a permit is needed either way.

Q. Should the new heater have a water softener installed at the same time?

Where water is hard, A. O. Smith's manual recommends water softening or a threshold-type treatment, and North County water is very hard by USGS classes. It is a separate decision with its own trade-offs, covered on the softeners page §2.3.

Q. Does selling a house involve the water heater?

Yes. Health & Safety Code 19211 requires every residential water heater to be braced, anchored or strapped, and its subsection (b) has sellers certify that the heater complies.

6.4.7 Sources for this section