The dip tube on a water heater is used to channel cold water from the inlet at the top of the unit down to the bottom, ensuring that the water is circulated and heated evenly. On models made between certain years, the tube is made of plastic, and may become clogged with sediments or break over time.
If you notice a decrease in water pressure or plastic particles in your water, you will likely need to replace the dip tube. This part can be easily (and cheaply) replaced without replacing the entire water heater.
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Determine Whether a Dip Tube is Present
Over 20 million water heaters with a polypropylene tube were manufactured between 1993 and 1996, accounting for nearly 90 percent of all water heaters made during the period. These tubes may crumble with age, eventually breaking off and falling to the bottom of the tank.
Look at the first four digits of the serial number. The third and fourth digits represent the year of manufacture. If the year of manufacture falls in the range of 93 thru 97, it probably has a dip tube that should be replaced. See How to Determine the Age of a Water Heater for more info.
How to Replace a Water Heater Dip Tube
Shut Off Power and Water
Before making any repairs to a water heater, always turn off the gas or electricity running to the unit. For electric units, turn off the circuit breaker in your electric panel.
For gas units, locate the dial and turn it to either the “Off” or “Vacation” position. The Vacation setting will not extinguish the water heater pilot light, the Off setting will. Turn off the cold water inlet valve on top of the water heater. If no valve is present, you may have to shut off water at the meter or pump.
Drain the Tank
Connect a garden hose to the hose bib near the bottom of the water heater. Extend the hose to a suitable drain or outside location. Place the end of the hose in a bucket and fasten it securely without kinking the hose.
Drain the water heater into the bucket, and allow it to keep draining even when the bucket begins to overflow. The purpose of the bucket is to catch sediments and debris from the tank, so you can use a filter screen instead, if you prefer.
Remove the Dip Tube
Disconnect the cold water inlet pipe. On some units this can be done with a pipe wrench, but most older models may require you to cut the pipe or tubing feeding the unit with a tubing cutter. There will be some leakage when the inlet pipe is disconnected, so have rags or sponges ready to remove it.
Use a pipe wrench to remove the inlet nipple (see pipe fittings). Do not use any form of penetrating fluid, as it can contaminate your hot water supply.
Gently tap the end of wrench as you apply pressure until the pipe begins to turn. The dip tube is connected to the end of the inlet nipple and may pull out with the nipple unless it has broken off inside the tank. Remove the pipe nipple from the dip tube.
If the dip tube is damaged or corroded, it needs to be replaced. Otherwise, you will need to troubleshoot the unit to find the real problem. Replace the tube anyway, to prevent potential problems later.
Install the New Dip Tube
Wrap the threads of the replacement dip tube with plumber’s tape or fill the threads with pipe joint compound. This ensures a better seal and helps prevent leaks. Attach the dip tube to the inlet nipple and insert it into the tank.
To reconnect a cut pipe, purchase a compression coupling from the hardware store and insert it over both of the cut ends of the pipe. For best results, wrap the threads of the coupling with plumber’s tape or joint compound.
Flush the Tank
Clean and flush the tank well before restoring power. The object is to remove any sediments or plastic particles from the tank, and the process should be repeated until no foreign objects are being washed out of the tank. Disconnect the drain hose and dispose of the captured debris.
Turn on the water inlet valve and allow the tank to fill before you restore power.