Gas vs electric is the simplest-sounding water heater decision and the most under-thought. Most homeowners default to whatever was there before because the alternative requires running a new gas line or upgrading a service panel. That defaulting behavior is usually right — but not always. Here are the specifics that determine when to break from the default.
The 30-second answer
Replace with the same fuel source you already have, unless: (a) you have gas available but the existing heater is electric and you have a 100A service that is preventing other upgrades, or (b) you have electric only and a heat-pump water heater would fit your space and climate. Switching fuel types is rarely worth the install cost unless triggered by another decision.
Monthly operating cost (national averages, 2026)
Assumptions: household of four, 60 gallons/day hot water, set to 120°F, US national average fuel prices.
- Natural gas tank (UEF 0.62): $33/mo at $1.20/therm.
- Natural gas tank (UEF 0.86 condensing): $24/mo.
- Propane tank (UEF 0.62): $67/mo at $2.80/gallon.
- Electric tank (UEF 0.92): $48/mo at $0.16/kWh.
- Electric heat-pump (UEF 3.45): $13/mo at $0.16/kWh.
Natural gas wins clearly against electric resistance — about $15/month, or $1,800 over 10 years. Propane loses to electric resistance in most pricing scenarios. Heat-pump beats everything else by a wide margin in any climate where the install location supports it.
Regional variation matters: in California and the Northeast where electricity runs $0.28–$0.35/kWh, electric resistance becomes a financial nightmare. In Washington State where hydro keeps electric at $0.10/kWh, the gap narrows to under $5/month. Always look up your specific utility rate before doing this math — national averages mislead.
Up-front cost
Like-for-like replacement (existing fuel source stays the same):
- Mid-grade 50-gallon gas tank installed: $1,400–$1,800.
- Mid-grade 50-gallon electric tank installed: $1,100–$1,400.
- 50-gallon heat-pump installed: $2,400–$3,400 (often offset by $300–$1,500 utility/tax rebates).
Electric resistance is cheapest on day one. Gas is cheapest on day-720. Heat-pump is cheapest on day-1,200.
Fuel switch cost (the actual reason most people stay where they are)
Converting electric to gas typically requires:
- Run gas line to heater location ($500–$2,000 depending on distance from meter).
- Install venting — B-vent up the chimney or PVC for condensing ($400–$1,500).
- Combustion air provisions in some basements ($200–$600).
- Permit and inspection ($150–$400).
- Total switching premium: $1,250–$4,500 above the tank cost.
Converting gas to electric typically requires:
- Run a dedicated 30-amp 240V circuit ($200–$600).
- Cap the gas line at the location ($100–$200).
- If switching to heat-pump, may need condensate drainage ($100–$300).
- Total switching premium: $400–$1,100 above the tank cost.
Electric → gas is much more expensive to convert than gas → electric. This asymmetry is why "default to existing fuel" is almost always the right move — the install premium swamps the operating cost savings.
The power-outage question (rarely discussed)
Modern gas tank water heaters with electronic ignition still need 120V power for the control board. When the power goes out, most gas tanks stop heating. The exception is units with thermopile-powered gas controls — Bradford White's ICON system and a few others. These keep running through power outages because the gas valve is driven by heat from the pilot, not from the grid.
Electric water heaters obviously stop in any outage. Tankless of either fuel type also stop because they need 120V for the control board and the fan (gas) or the elements (electric).
If you live in an area with frequent outages and want hot water during them, your only real option is a Bradford White or similar atmospheric gas tank with thermopile control. This is a niche concern but a real one for parts of the Gulf Coast, hurricane-prone areas, and rural ice-storm regions.
Venting matters
Gas water heaters must vent combustion products. Three vent types in residential use:
- Atmospheric / natural draft. Vents up a brick chimney or through a metal B-vent. Cheapest and oldest. Requires a chimney path. Vulnerable to backdrafting under negative pressure.
- Power vent. Uses an integrated fan to push exhaust through PVC or metal vent pipe horizontally. Can vent through a side wall — no chimney needed. Costs $200–$500 more than atmospheric.
- Direct vent / condensing. Sealed combustion, two-pipe PVC venting. Highest efficiency, longest possible runs. Costs $300–$700 more in venting hardware.
If your existing heater is atmospheric and you want to switch to condensing for efficiency, you need to either re-vent through a side wall or run new flue liners. Many homeowners don't realize this and discover it during install — adding $500–$1,500 to the project.
Electric heaters require no venting at all. This is the single biggest install simplifier favoring electric in tight spaces (closet installations).
Safety and code differences
Gas water heaters require: combustion air (typically 50 ft² of un-obstructed room around the unit, or a powered combustion air intake), proper venting, and a CO detector within 15 feet. Some jurisdictions require seismic strapping (California, others). Most jurisdictions require the heater to be 18 inches off the floor in garages where gasoline vapors might pool.
Electric water heaters require: proper electrical disconnect within sight of the unit, a 30A 240V circuit with appropriate wire gauge, no garage floor restrictions, no venting requirements. Code complexity is meaningfully lower.
This is part of why electric is the default for new construction in markets with no existing gas service — adding gas requires multiple trades and inspections.
Who wins
Gas wins for: households in cold climates (Northeast, Midwest, Mountain West) where electric resistance bills genuinely bite; households of four or more (recovery rate matters more); homes with existing gas service and atmospheric venting already in place.
Electric wins for: apartments and condos where gas service is unavailable; small households (1–2 people) where the monthly operating gap is under $10; homeowners with rooftop solar where excess PV production can offset water heating; basements that fit a heat-pump unit (huge winner).
Heat-pump (electric) wins for: almost every household with a basement or large utility room install location. Lower operating cost than even condensing gas. Federal and utility rebates often make the install cost competitive with standard electric. The only reason not to is the install location constraint.