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Water heater temperature should be set to 120°F (49°C). The "temp" abbreviation suggests buyers looking for a quick answer — this page provides that, plus the reasoning and the deviation cases.

The 30-second answer

Set your water heater to 120°F. That's it. This is the recommendation of every major US safety organization (EPA, OSHA, CPSC, AMA). Higher temperatures increase scald risk significantly. Lower temperatures allow Legionella bacteria to multiply in the tank.

How to check your current setting

Place a meat thermometer in a running hot tap after the unit has cycled (wait 15 min from last use). The reading is your actual delivered temperature. The dial on the unit is approximate — actual delivery can differ by 5-15°F.

How to change the setting

Gas tank water heater

Dial on the gas control valve at the bottom front of the unit. Turn to the desired setting. Modern units: digital scale 100-140°F. Older units: "WARM/HOT/A-B-C" with A≈120°F.

Electric tank water heater

Two thermostats (one per heating element). Power off, remove access panels, set both to same temperature. Restore power.

Tankless water heater (any fuel)

Digital display on the unit. Adjust via up/down buttons. Setpoint range 100-140°F typical.

Heat-pump water heater

Digital interface, often WiFi-connected. Eco mode at 120°F is the typical default.

When higher than 120°F

  • Older dishwasher cleans poorly → try 125°F or 130°F
  • Long pipe run delivering tepid water → 130°F at heater
  • Immunocompromised household member → 140°F with thermostatic mixing valves at fixtures
  • Vacation home unused for long periods → 140°F when occupied, vacation mode when not

Energy impact of setting choice

SettingAnnual operating cost (typical gas tank household)
140°F$440
130°F$408
120°F$376

Each 10°F reduction saves about $30-$40/year. Standardize at 120°F for most households unless one of the higher-setting reasons applies.

Why not below 120°F

Legionella bacteria peak growth zone is 86-113°F. Settings below 120°F let bacteria flourish in the tank. Aerosolized through showerheads, Legionella causes Legionnaires' disease. The $15-$25/year savings from setting below 120°F is not worth this risk.

3 products
$949 – $1,795
Updated May 2026

Quick Comparison

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