What is a Dip Tube in a Hot Water Heater?

Hot water plays an essential role in our everyday lives, especially when it comes to important things like cleaning and bathing. What do you do then when you suddenly have a shortage of hot water? You know this has something to do with the water heater, so you go down and check, but what are you looking for?

The thermostat looks fine, so what else could it be? Well, when it comes to hot water issues like this, your problem may be due to nothing more than a broken or defective dip tube. What is a dip tube in a hot water heater, you may ask?

Though perhaps not as common in most residential homes, tankless water heaters do not require dip tubes as they do not have storage tanks. Cold water just goes through a pipe and is heated up by either a gas burner or electric element.

close up bare young woman reacting while taking cold shower with arms crossing over her chest and eyes closed

Read on for the answer!

So, what is a dip tube in a hot water heater? It is a long plastic tube that is attached to the cold-water inlet at the top of your water heater and ends near the bottom of your tank. The purpose of this tube is to guide the water heater’s incoming cold water to where the electric heating element or gas burner is at the bottom of the storage tank.

Want to learn more about troubleshooting faulty dip tubes and how to install a replacement? Keep scrolling for more information!

What Are the Different Parts of a Dip Tube?

A dip tube has two different features to be aware of: the anti-siphoning hole near the top and the cut-out slots at the bottom.

Anti-Siphoning Hole

There is a hole about 1/8″ in diameter, and about 6″ from the dip tube’s connection point called an anti-siphoning hole. It keeps the water from the heater’s storage tank from going up through the dip tube and out of the tank.

Bottom Slots

The slots at the bottom of the dip tube help release water in an uneven spray, creating turbulence. This turbulence is necessary for keeping the water moving around the tank; otherwise, sediment or mineral deposits might settle at the bottom of your water heater. If this kind of debris ends up settling at the bottom of the tank, it can reduce the efficiency of the heating element.

How Do I Know If My Water Heater Dip Tube Is Bad?

The most common signs that you may notice are the following:

  • Weak hot water pressure and flow
  • Quickly running out of hot water
  • In a sink aerator or showerhead, the presence of small broken white plastic particles
  • If you look in your water heater, a white sticky sludge on the inside of the tank

How Much Does It Cost to Replace a Dip Tube?

If you are looking to have it replaced professionally by a plumber, it can cost up to $150. However, if you are handy and comfortable doing it yourself, a new dip tube by itself may only be about $10.

How Do You Replace a Dip Tube?

replace a dip tube

If you would like to try replacing a dip tube yourself before calling a plumber, try the following steps.

Step 1: Gather Materials

  • Pipe wrench
  • Pliers
  • New dip tube*
  • Teflon tape

*Consider purchasing a dip tube made of cross-link polyethylene as it should not break down in the water heater.

Step 2: Turn Off Power and Water

Make sure your water heater is turned off, and you have closed off the water inlet on the main valve.

Step 3: Drain

Drain both the cold-water supply line located at the top of the water heater, and remove some water from the tank. Note that you do not need to completely drain the tank – a gallon or two will suffice.

Step 4: Begin to Remove Dip Tube and Ring Gasket

Unscrew the pipe connector with the pipe wrench. Depending on your model, the dip tube may be connected to the steel inlet nipple, so just remove the nipple, and then the tube should come out easily. Take out the ring gasket.

Step 5: Pull Out the Old Dip Tube

Look back to the cold-water inlet hole at the top of the tank and pull the rest of the dip tube out of there, using pliers if necessary.

Step 6: Install New Dip Tube

Reverse the steps of everything you did to remove the old dip tube to install the new dip tube. Remember the ring gasket that needs to be placed back in the connector sleeve. Secure your new dip tube with Teflon tape.

Step 7: Reconnect, Refill, Restore

Reconnect the cold-water supply line and refill the tank of the water heater. While refilling the heater, it is important to release any air that may have built up in there, so to do this, open a faucet on the hot side of the fixture. You are now ready to turn on your water heater.

Step 8: Test

Ensure that your new dip tube and the rest of your water heater are working properly by turning on the hot water in your house.

Is a Dip Tube Necessary?

While your water heater will still technically work without one, a dip tube is important if you want to be able to get especially hot water. If you did not have a dip tube, the cold water coming into the tank would just mix with the hot water at the top before making its way out, resulting in just lukewarm water flowing out of the faucets.

How Long Should a Water Heater Dip Tube Be?

That depends a bit on your water heater. The dip tube needs to start at the top as it fits into the cold-water outlet of the water heater and should stop around 8 inches from the bottom. Dip tubes usually come in standard sizes, so they can be cut to fit your water heater.

Do All Water Heaters Have Dip Tubes?

Nearly all electric water heaters and gas water heaters have dip tubes if their cold-water inlets are located at the top. However, some water heaters have their cold-water inlets at the bottom of the tank, which do not require dip tubes.

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