How to Adjust Your Water Heater Temperature Safely

Most water heaters leave the factory set higher than they need to be, often around 140°F. That extra heat doesn't just cost you money every month, it also raises the risk of scalding, particularly for kids and older adults. Dialing it back to a safer, more efficient setting is a five-minute job.

Why 120°F is the sweet spot

At 120°F, water is still plenty hot for showers, dishes, and laundry, but it takes several minutes of contact to cause a serious burn. At 140°F, a third-degree burn can happen in a matter of seconds. On top of the safety angle, every 10-degree reduction in your water heater's setting can meaningfully cut the energy used to maintain that temperature, since the tank spends less time and energy fighting heat loss to reach a lower target.

Adjusting a gas water heater

1. Locate the temperature dial on the gas control valve near the bottom of the tank. It's usually marked with a range from "warm" to "hot," or sometimes with actual temperature numbers.
2. Turn the dial to the setting closest to 120°F. If your unit only has warm/hot markings without numbers, aim for a point below the midpoint, and plan to test and adjust.
3. Wait a few hours for the tank to adjust to the new setting, then check the temperature at a faucet using a simple kitchen thermometer.
4. Fine-tune the dial slightly if needed and re-test.

Adjusting an electric water heater

Electric units are a bit more involved because the thermostat is usually behind an access panel, and safety requires cutting power first.

1. Turn off the breaker dedicated to the water heater at your electrical panel. This step isn't optional. Electric water heater thermostats are live and working on them with power on risks a serious shock.
2. Remove the access panel (usually one or two screws) and move aside the insulation covering the thermostat.
3. Many electric units have two thermostats, one upper and one lower. Adjust both to the same setting, around 120°F, using a flathead screwdriver.
4. Replace the insulation and panel, restore power at the breaker, and wait a few hours before testing the water temperature at a faucet.

A note on lower settings

Going much below 120°F isn't recommended either. Water heaters that run too cool, generally below about 110°F, can allow bacteria like Legionella to survive and grow inside the tank, which is a genuine health consideration, not just theoretical. The 120°F range balances safety, energy use, and water quality reasonably well for most households.

Households with extra scald risk

If you have young children, older adults, or anyone with reduced sensitivity to heat living in your home, some households choose to set the tank slightly lower, closer to 115°F, and pair it with anti-scald devices at individual fixtures for extra protection. This is a personal decision based on who's in your home, but it's worth thinking through rather than just leaving the factory setting untouched.

When to leave it to a professional

If your dial doesn't seem to correspond to a clear temperature, if you're not comfortable working around an electric unit's internal thermostat with power involved, or if adjusting the temperature doesn't actually change the water coming out of the tap, something else may be going on with the thermostat or heating element. In that case, ProFlow Plumbing can diagnose and correct it safely rather than leaving you guessing at a dial that isn't doing what it should.