Gas water heater replacement in Fairfax, VA
Quick answer: A natural-gas water heater — tank or tankless — is still the most common type in many Fairfax County, Arlington, and Alexandria homes that already have gas service. Gas tanks typically recover faster than a comparable electric resistance tank. They also come with venting, combustion-air, and permit requirements that an electric swap does not always have.
In Virginia, replacing a gas water heater requires a permit, even when the new unit is a like-for-like replacement. That rule comes from the Virginia Construction Code: the exemption for replacing mechanical appliances in certain homes applies only to equipment not fueled by gas or oil (13VAC5-63-80). Fairfax County says the same in plain language on its Household Appliance permit page.
Tank vs tankless on gas
Gas storage tanks
The straightforward replacement in a basement or garage: same fuel, same general footprint, shorter install path when the vent and gas line already fit. See also water heater replacement.
Gas tankless
Can make sense when you want on-demand capacity or wall space, but it often needs a larger gas supply and different venting. See tankless installation.
If the home is all-electric today, switching to gas is a different project (new piping, a meter or service change, Washington Gas coordination in the City of Fairfax, and a plumbing permit rather than a simple appliance swap). Ask about that path only if you actually want it; a like-for-like electric or heat pump unit may be cleaner. Electric and heat pump.
If you smell gas
Leave the home and call Washington Gas or 911 from outside. Do not operate light switches or use a phone inside. First-aid steps for a water leak are on the emergency leak page.
Venting and chimney certification
Gas water heaters have to send combustion gases outside. Older Fairfax-area homes sometimes share a chimney with a furnace or have a flue that is no longer the right size for a modern appliance. Fairfax County requires a chimney vent certification for the replacement or installation of all fuel-burning appliances in existing buildings. Arlington also requires a completed chimney vent certification when a fuel-burning appliance is replaced.
A quote should say whether the existing vent can stay, whether a power-vent or direct-vent conversion is in scope, and who is providing the certification. Skipping that conversation is how a “cheap” swap fails inspection.
Combustion air, sediment traps, and TPR discharge
A finished gas job also has to get the unglamorous details right:
- Combustion air for the burner (especially in a tight closet)
- A properly configured gas connection and sediment trap
- A TPR valve with a discharge pipe routed to an approved location — not aimed at an electrical panel, and not capped
- Clearances from combustibles
- An expansion tank where the water system is closed
Permits, by the short version
- Fairfax County: Household Appliance (HAPL) permit in PLUS when there is no new gas piping; Residential Plumbing permit if new gas pipe is part of the job. Automatic issuance after a complete HAPL filing; then a required inspection.
- Towns of Vienna or Clifton: PLUS plus a separate town approval, uploaded to the record.
- City of Fairfax: its own portal; a gas water heater needs a gas permit and a plumbing permit — the City of Fairfax is not Fairfax County.
- Arlington: Plumbing/Gas permit through Permit Arlington.
- Alexandria (the city): APEX / Code Administration.
- Woodbridge / Prince William County: a gas permit; the county lists replacing gas appliances, water heaters included, under “permits always required.”
Full links: permits guide.
Rebates
Washington Gas currently advertises Virginia rebates of $200 for storage water heaters at 0.81+ UEF, $300 at 0.86+ UEF, and $400 for ENERGY STAR tankless, through a participating contractor. Confirm eligibility and the current table on that page before you count on a rebate.
Source: Washington Gas, retrieved 2026-11-13.
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Does a like-for-like gas swap really need a permit?
Yes, in the Virginia jurisdictions we cover. Fairfax County is explicit that gas appliances are not exempt, even for a like-for-like replacement.
What if the heater failed over the weekend?
Virginia’s building code allows emergency equipment replacement to start, with the permit application submitted by the end of the first working day after the work begins. That is not a reason to skip the permit; it is a timing rule for true failures.