The dip tube routes cold inlet water to the bottom of the tank. When broken, cold water mixes immediately with hot water — lukewarm output that runs out fast.
Symptoms
- Hot water runs out in 5-10 minutes
- Water lukewarm rather than hot
- Sudden onset
- White/cream plastic flakes in faucet aerators
DIY replacement
- Off power/gas
- Close cold supply; open hot tap to relieve pressure
- Disconnect cold supply line
- Unscrew cold inlet nipple
- Pull out dip tube
- Insert new dip tube
- Reinstall nipple with Teflon tape
- Reconnect supply; purge air
Cost
- Universal: $5-10
- OEM: $10-20
Bottom line
Cheapest water heater repair. Runs-out-fast + sudden onset + plastic in aerators = dip tube.