Colorado’s new water heater rules took effect January 1, 2026. Most Aurora homeowners only find out when a tank fails. Here is what each rule actually says, in plain terms.
Colorado’s 2026 Water Heater Rules in Plain Terms
Colorado House Bill 23-1161 requires every new gas-fired water heater sold or installed in the state to meet Ultra-Low NOx (nitrogen oxide) emission limits as of January 1, 2026. The law does not ban gas water heaters. It does not require you to replace a working unit. Existing units can still be serviced and repaired indefinitely. The limits apply only to new equipment.
The specific NOx limits:
- Residential tanks under 75,000 BTU/hr: 10 ng/J maximum
- Commercial units 75,000 to 2 million BTU/hr: 14 ng/J maximum
Your three replacement paths in Aurora:
- Ultra-Low NOx gas tank: Bradford White, Rheem, A.O. Smith
- Ultra-Low NOx tankless gas unit: Navien, Lochinvar
- Electric heat pump water heater: zero NOx at the unit, qualifies for the most utility rebates
Non-compliant units already in Colorado inventory before January 1, 2026 can still be installed until that stock runs out.
Do I Need a Permit to Replace My Water Heater in Colorado?
Yes. The City of Aurora Building Division requires a plumbing permit for water heater replacements, with a city inspection on completion. Aurora enforces the 2021 International Residential Code with Colorado amendments.
Permit requirements by install type:
- Same-for-same tank replacement: plumbing permit only
- Tank to tankless conversion: plumbing permit plus electrical permit, larger gas line often required
- Tank to heat pump: plumbing permit plus electrical permit, dedicated 240V/30A circuit, condensate drain, 700+ cubic feet of clearance
Permit fees in Aurora run $150 to $750 depending on scope. A licensed plumber pulls the permit on your behalf. Skipping the permit can void homeowner insurance claims and create disclosure issues at the time of sale.
Can You Have a Gas Water Heater in Colorado?
Yes. Gas water heaters are fully legal in Colorado after January 1, 2026. The law changes what kind of gas water heater can be installed, not whether you can have one.
Three points to know:
- Existing gas units can stay in service, be repaired, and have parts replaced indefinitely
- A new gas unit installed in 2026 must be Ultra-Low NOx certified
- Compliant brands: Bradford White, Rheem, A.O. Smith (tanks) and Navien, Lochinvar (tankless)
Ultra-Low NOx units use redesigned burners. Upfront cost runs higher than the standard models they replace. Performance and lifespan are comparable.
What Is the Federal Tax Credit for Tankless Water Heaters in 2026?
There is no federal tax credit for tankless water heaters in 2026. Section 25C of the federal Energy Efficient Home Improvement Credit was repealed by the One Big Beautiful Bill Act, signed July 4, 2025. The repeal applies to any unit placed in service on or after January 1, 2026.
Key dates:
- Units placed in service in 2023, 2024, or 2025: still eligible for up to $600. Claim using IRS Form 5695 with the manufacturer’s PIN
- Units placed in service on or after January 1, 2026: no federal credit applies
Utility rebates are the path forward in 2026. Xcel Energy still offers rebates on heat pump water heaters in the Aurora service area. The rebate is typically applied at the time of install.
What Is the Hot Water Law in Colorado?
Colorado’s plumbing code caps domestic hot water at 140°F (60°C) at the water heater outlet. At higher-risk fixtures, delivered water must be lower.
Code requirements at a glance:
- Maximum hot water at the source: 140°F at the tank or tankless outlet
- Maximum delivered water at tubs and showers: 120°F at the valve, enforced through an ASSE 1016 anti-scald shower valve
- Combined potable and space-heating systems running above 140°F: ASSE 1017 master thermostatic mixing valve required
- Closed systems (most Aurora homes): expansion tank near the water heater
An Aurora city inspector confirms each applicable item at permit close-out.
Not Sure Where Your Water Heater Stands?
If your water heater in Aurora is more than ten years old, a quick assessment now is easier than a Saturday-morning emergency call. Whether the right move is Aurora water heater repair or a compliant replacement, we can walk through what is installed, where it stands against current code, and which option fits the home best.
Call us now for fast service! Reach Superior Mile High Plumbing at (303) 304-0784.