Symptoms
- Hot water lasts only a few minutes per shower
- Problem has gotten worse gradually over time
- Household usage has increased (more people, more showers)
- Water heats but doesn't stay hot long
Likely causes
- CommonSediment buildup reducing usable tank volumeSediment settles at the bottom and takes up space while also insulating the burner or lower element from the water.
- CommonTank undersized for current household demandA 40-gallon tank that once served two people may struggle with four.
- PossibleLower heating element failed (electric) or burner running weak (gas)A working upper element/burner alone gives less usable hot water.
- PossibleThermostat set too lowA lowered setting, sometimes from a previous energy-saving adjustment, reduces available hot water.
What to do
- Check the thermostat setting; 120°F is a common safe default, but confirm it hasn't been turned down further.
- Note whether the amount of hot water has been shrinking gradually, which points to sediment.
- Flush the tank by draining several gallons from the drain valve to see if sediment comes out (see the flushing guide for the full process).
- For electric units, have the lower element tested if flushing doesn't help.
- For gas units, check that the burner flame looks steady and blue, not weak or yellow.
- If usage has genuinely grown, compare your tank's gallon capacity and recovery rate to your household's needs.
Tools and parts
- Garden hose (for flushing)
- Multimeter (for electric element testing)
Lower heating elementSearch: “electric water heater lower heating element”
When to call a pro
If flushing and checking elements don't help, or the tank is clearly undersized, a plumber can recommend a larger tank or a tankless upgrade.
Safety
Use caution
Let the water cool before draining any water from the tank to avoid scalding, and shut off power or gas before working on elements or the burner.