Water Heaters - What is a Dip Tube and What does it do?

Dip tubes, although simple, are very important to the operation of gas and electric water heaters. Without a dip tube you won't get much hot water.

Water Heater Dip Tubes

The dip tube in your water heater, (and nearly all water heaters have them), is a long plastic tube that fits into the inlet of the water heater and stops at about 8 inches above the bottom of the tank.  Some water heaters have the cold water inlet at the bottom of the tank, and those water heaters do not need a dip tube since the cold water is already entering the tank from the bottom.

The dip tube is designed to direct the incoming cold water to the bottom of the heater.  Without a dip tube the cold water coming into heater would just mix with some of the hot water at the top of the tank on its way to the outlet.  You would get tepid water out of your faucets.

If your dip tube breaks off, you will only be able to get tepid water from your water heater, or it will seem to run out very quickly.  It depends on how much of the dip tube broke off.illustration showing the dip tube and all of the parts of a gas water heater

Broken or damaged dip tubes

If your water heater was built between 1993 and 1996, it might have a defective dip tube. Ninety percent of all water heaters built from 93 to 96 used the tubes, and after a few years of exposure to hot water many of them are disintegrating and breaking off.

 If you think your water heater may be affected, check the serial number on the tank. The first 4 numbers in the serial number are usually the month and year of manufacture.  Affected water heaters will have the numbers 93, 94, 95, 96 or 97 in the third and fourth digit.

Small bits of plastic

A big clue is if you begin finding small bits of plastic in your faucet aerators, shower head, clogging strainers and filter screens on appliances.

To replace a broken or damaged dip tube is easy in theory, but in reality sometimes it can be very difficult to remove an old rusted in pipe nipple from the inlet fitting on the water heater.  Some dip tubes have a flared end, and you drop the tube in and thread in the inlet nipple which holds it in place. Others are molded into the nipple itself.

Curved dip tubes to reduce sediment

Some manufactures use a dip tube with a curved bottom that in theory swirls the water around to reduce sediment buildup and to make it easier to flush the sediment out.  You can curve the end of a dip tube by heating it over a flame and bending it by hand.

Dip tubes have to be made of plastic, because if they were made of say copper, they would quickly destroy the anode rod and your water heater could quickly develop leaks.

Dip tubes can be purchased online for under $10.00