What Is an Immersion Water Heater?

By Elizabeth Marcant

November 01, 2025

You probably don’t think much about what heats the water in your shower or sink unless it stops working. However, hidden inside most electric water heaters is a small component called an immersion heater. This metal rod quietly does the work of turning cold water into the hot stream you relax under in the shower or use to wash dishes or do laundry.

This May Also Interest You: How Much Does It Cost to Replace a Water Heater?

Understanding how this part works can help you better maintain your water heater and understand when a repair is needed. It can also help you learn how you might heat water in situations outside your home.

What Is an Immersion Heater?

In most North American homes, an immersion heater is a specific component. It's an electric heating rod that sits inside the water heater tank. As electricity flows through the rod, it heats up. In turn, the water around the rod heats up.

Standard electric water heaters have immersion heaters inside of them. The heating elements in such water heaters are components rather than separate appliances. However, portable immersion water heaters are available for use in camping and agriculture.

How Do They Work?

Immersion water heaters rely on electrical resistance to generate heat. Inside the metal rod, high-resistance wire is coiled tightly. It's inside a sheath, so it never has direct contact with the water. When electricity moves through the wire, the resistance creates a type of friction, which results in heat. The heat from the wire transfers to the metal sheath and then into the water.

In most electric water heaters, a thermostat monitors water temperature and cycles the immersion element on and off to maintain the set temperature. Some systems use two elements, one near the top of the tank and another near the bottom, so water can be heated more evenly.

More Related Articles:

How Much Do Immersion Water Heaters Cost?

The average cost of replacing a water heater element in a residential electric water heater is $100 to $350 (CAD 140 to CAD 490). You might need to replace one or both heating elements in your water heater if you aren't getting a consistent supply of hot water. If your water starts nice and hot but runs out quickly, it could indicate a need to replace the lower heating element. If you get consistent warm water but it's not very hot, the upper element may need attention.

To find out whether one of your immersion heater elements needs replacing, talk to a plumber. A professional with water heater repair experience can help you understand what exactly may be wrong. They can also explain the cost of replacing a damaged element and whether you might be better off installing a new or more efficient unit.

Portable Immersion Water Heaters

In cases where people need a small and portable way to heat water, portable immersion water heaters can work well. You can use them to heat water in buckets, hot tubs or livestock troughs, for example. Farmers and ranchers might use them to ensure water in troughs doesn't freeze in winter, and those who live in RVs or at campgrounds might use immersion water heaters to heat water for washing dishes, supplying stand-alone showers or doing laundry.

Costs for these types of stand-alone immersion water heaters can vary from $25 to $200 (CAD 35 to CAD 280) or more. Pricing factors include the brand and quality of the part, how powerful it is, the type of voltage used and whether it has features like a thermostat and automatic on/off options.

Note that buying a portable immersion water heater is completely different from replacing the immersion heater element in your home's water heater. You can't substitute the portable appliance you'd use to heat a bucket of water while camping for your home water heater's element if it goes bad, for example. If your home water heater isn't working well and you think a new component might be required, reach out to a professional for the repair.

Follow us