Quick answer
If hot water runs out much faster than it used to, something has changed in the heater. On electric heaters, a failed lower element is the most common cause: the upper element still heats the top of the tank, so you get a short burst of hot water. Heavy sediment takes up tank space and insulates the burner on gas heaters. A broken dip tube lets cold water mix at the top. A thermostat turned down, or a household that has outgrown the tank, also shortens it. Call (888) 217-6781 to reach a plumbing company taking calls in your ZIP.
Follow the short menu, then your 5-digit ZIP. The line goes quiet for a few seconds while it connects; stay on. If it does not connect, call once more: companies taking calls change minute to minute.
Written & reviewed by Marcus ReedIICRC WRT
Reviewed November 4, 2026· Next review May 2027
A tank water heater should give a predictable amount of hot water. When showers suddenly go cold halfway through, a part has usually failed or the tank has lost capacity.
Sudden or Gradual?
| How it changed | Likely cause |
|---|---|
| Sudden, electric heater | Lower heating element or its thermostat failed |
| Gradual over months or years | Sediment buildup taking up tank space |
| Hot at first, lukewarm quickly | Broken dip tube |
| After someone adjusted it | Thermostat turned down |
| After a new family member or fixture | Tank too small for the demand |
Electric Heaters: Two Elements
Most electric tank heaters have an upper and a lower element. The upper heats first, then the lower takes over. If the lower element fails, only the top of the tank gets hot and hot water lasts a few minutes. See water heater element replacement.
Sediment
Minerals settle at the bottom of the tank, especially with hard water. On gas heaters, the layer insulates the water from the burner and may cause rumbling. Flushing the tank can help if it is done before the sediment hardens. See water heater maintenance.
Talk to a plumber about this
One call reaches a plumbing company taking calls in your ZIP.
The Dip Tube
The dip tube carries cold water to the bottom. A cracked or dissolved tube, a known problem in some heaters from the 1990s, lets cold water mix at the top. Bits of white plastic in faucet aerators are a sign.
Tank Size
The Department of Energy sizes heaters by first-hour rating, the hot water it can deliver in a busy hour. A household that grew may need a larger tank or a tankless unit. See tankless vs tank water heater.
The Call
Call when the thermostat is set right and hot water still runs out early. (888) 217-6781 connects you to a plumbing company taking calls in your ZIP. Follow the short menu, enter your 5-digit ZIP and stay on while it connects; if it does not connect, call once more, because the companies taking calls change minute to minute.
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Frequently Asked Questions
Why does my hot water run out so fast?
A failed lower element on electric heaters, heavy sediment, a broken dip tube, a thermostat set low, or a tank that is too small for current use.
How do I know if my water heater element is bad?
Hot water lasts only a few minutes, or there is none. With power off and wires disconnected, an element that reads no continuity, or reads to the tank, has failed.
What does a broken dip tube do?
The dip tube carries incoming cold water to the bottom of the tank. When it breaks, cold water mixes at the top near the outlet, so hot water turns lukewarm quickly.
Sources
- U.S. Department of Energy: storage water heaters
- U.S. Department of Energy: tips for lowering water heating costs
Methodology: How we source and verify data · Report an error
Disclaimer: HearthDry is an independent educational resource. This article is for informational purposes only and does not constitute professional, legal, or insurance advice. Consult licensed professionals before making decisions about your property or insurance claims.
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