Electric water heaters in RVs heat water using 120-volt or 240-volt shore power, not propane or engine heat

An RV electric water heater is a tank that warms water when your RV is plugged into a campground pedestal or connected to a generator. Unlike propane water heaters, which work whether you're plugged in or not, electric models only function when you have external power available. Most RVs come with propane heaters as standard, so an electric heater is usually an add-on or a replacement you choose yourself.

The heating element inside works like a household electric water heater — electricity passes through a metal coil that gets hot and transfers that heat to the water around it. A thermostat controls the temperature, typically set between 100 and 140 degrees Fahrenheit. When the water cools, the element turns back on automatically.

Electric heaters are popular with RV owners who spend most of their time at established campgrounds with full hookups, because they're cheaper to run than propane and they heat water faster than many propane models. However, they're useless when boondocking or dry camping without shore power.

Key Takeaways

  • Electric water heaters require 120-volt or 240-volt shore power and cannot operate off-grid or while traveling.
  • Most RVs come with propane heaters; electric models are add-ons or replacements that work alongside or instead of propane.
  • Tank size ranges from 6 to 20 gallons in most RVs, and larger tanks take longer to heat but provide more hot water before running out.
  • Installation requires running new electrical wiring to the water heater location and may need a dedicated breaker on your RV's electrical panel.
  • Electric heaters cost less per gallon to heat than propane but only work at campgrounds with full hookups or when connected to a generator.

Tank size and how long it takes to heat water

RV electric water heater tanks typically hold between 6 and 20 gallons. Smaller tanks (6 to 10 gallons) heat up in 20 to 30 minutes on 120-volt power and 10 to 15 minutes on 240-volt power. Larger tanks (15 to 20 gallons) take 45 minutes to over an hour on 120-volt and 20 to 30 minutes on 240-volt.

The difference matters if you're taking a quick shower or filling a bathtub. A 6-gallon tank gives you roughly 5 to 10 minutes of hot water at normal shower temperature, depending on how hot you like it and how much cold water mixes in. A 10-gallon tank extends that to 15 to 20 minutes. If you have multiple people showering back-to-back, a larger tank or a propane heater running simultaneously will prevent you from running out of hot water.

Heating speed also depends on your shore power setup. Most campgrounds provide 30-amp service, which delivers 120-volt power. Full hookup sites with 50-amp pedestals can supply 240-volt power, which heats water roughly twice as fast. If you're using a generator, check its wattage — a small portable generator may not supply enough power to run an electric heater efficiently.

Voltage options: 120-volt versus 240-volt

A 120-volt electric water heater draws power from a standard household-style outlet and is the easiest to install in most RVs. It uses less power overall, so it works with 30-amp service at a campground. The trade-off is slower heating — a 10-gallon tank typically takes 30 to 45 minutes to reach full temperature.

A 240-volt heater requires a dedicated 240-volt circuit, which is only available at 50-amp campground pedestals or from certain RV-rated generators. It heats water roughly twice as fast as 120-volt and is more efficient, meaning less energy wasted as heat loss. However, it draws more power, so running it while using other high-draw appliances (air conditioning, electric stove) can trip your breaker.

Many RV owners with 50-amp service install a 240-volt heater because the speed and efficiency justify the extra installation cost. Those with 30-amp service or who camp at older sites with only 30-amp pedestals typically choose 120-volt. Some RVs come with dual-voltage heaters that work at either voltage, though these are less common and more expensive upfront.

Installation requirements and electrical considerations

Installing an electric water heater requires running electrical wire from your RV's breaker panel to the heater location, usually under the RV or in a cabinet. For a 120-volt heater, you'll need a dedicated 20-amp breaker and 12-gauge wire. A 240-volt heater needs a 30 or 40-amp breaker (depending on the heater's wattage) and 10-gauge wire.

The breaker panel in your RV has limited space, so you may need to replace an existing breaker with a tandem breaker to free up room, or install a subpanel if your main panel is full. If you're not comfortable working with electrical systems, a mobile RV technician can handle the installation — costs typically range from $300 to $800 depending on wire distance and whether the panel needs modification.

You'll also need to decide whether to replace your existing propane heater or install the electric heater alongside it. Many RV owners keep both: the propane heater for boondocking and the electric heater for campground use. This requires two separate tanks and two sets of plumbing connections, which takes up more space but gives you flexibility. Some RVs have a single tank with both a propane and electric heating element built in, which simplifies the setup.

Operating costs compared to propane

Electric heating is generally cheaper per gallon than propane, but the total cost depends on local electricity rates and propane prices, which vary by region and season. Heating 10 gallons of water from 50 degrees to 120 degrees typically costs between $0.50 and $1.50 in electricity, depending on your local rate. Propane for the same job usually costs $0.75 to $2.00.

The real savings come if you shower frequently or use hot water for laundry and dishes. Over a week at a campground, an electric heater can save $5 to $15 compared to propane, depending on usage. However, if you boondock regularly, propane becomes your only option, so the electric heater sits unused and adds weight and complexity without benefit.

Electricity rates at campgrounds vary widely. Some charge a flat fee for full hookups; others meter usage and bill separately. Ask the campground office about their electricity rate before assuming you'll save money. In areas with high electricity costs, propane may actually be cheaper even at a campground with full hookups.

Maintenance and common issues

Electric water heater elements can develop mineral buildup over time, especially in areas with hard water. This buildup reduces heating efficiency and can eventually cause the element to fail. Flushing the tank once a year — draining it completely and refilling it — helps remove sediment. If your water heater stops heating or heats very slowly, a mineral-clogged element is often the culprit.

The thermostat can also malfunction, causing the heater to overheat or not heat at all. Most RV water heater thermostats are not field-replaceable; you'll need a technician to swap it out. Thermostats typically cost $50 to $150 plus labor.

Check the anode rod (if your heater has one) every two years. This sacrificial metal rod corrodes instead of the tank, extending the heater's life. When it's mostly gone, replace it before the tank itself starts to rust. Anode rods cost $20 to $40 and take 30 minutes to replace if you're comfortable with basic plumbing.

When an electric heater makes sense for your RV

An electric water heater is worth installing if you spend most of your time at established campgrounds with full hookups and want faster hot water recovery than your propane heater provides. It's also useful if you have a large family or shower frequently, because the electric element can run simultaneously with a propane element to heat water faster.

An electric heater is not practical if you boondock regularly, camp at primitive sites without shore power, or travel constantly between different campgrounds. In those situations, propane is your only reliable option, and adding an electric heater just adds weight and complexity.

If you're undecided, consider a hybrid approach: keep your propane heater and add a small 120-volt electric heater. The 120-volt model is cheaper to install, works at any campground with 30-amp or 50-amp service, and gives you a backup if your propane heater fails. You can always upgrade to a larger or 240-volt model later if you find you're using it frequently.

Frequently Asked Questions

Can I run an electric water heater while driving or boondocking?

No. Electric heaters only work when connected to shore power or a generator. If you're traveling or at a site without power, the heater is off. This is why most RV owners keep a propane heater as backup, even if they install an electric model for campground use.

Will an electric water heater work with my 30-amp campground service?

Yes, a 120-volt electric heater works with 30-amp service. However, running it while using other high-draw appliances like air conditioning or an electric stove may trip your breaker. A 240-volt heater requires 50-amp service and will not work on 30-amp pedestals.

How much does it cost to install an electric water heater in an RV?

Installation typically costs $300 to $800 if you hire a mobile RV technician, depending on wire distance and whether your electrical panel needs modification. The heater itself costs $200 to $600. DIY installation is possible if you're comfortable with electrical work, but mistakes can damage your RV's electrical system.

Can I have both a propane and electric water heater in my RV?

Yes. Many RV owners install both to have flexibility — propane for boondocking and electric for campgrounds. This requires two separate tanks or a single tank with dual heating elements. The trade-off is extra weight, plumbing complexity, and space taken up by two systems.

What size electric water heater do I need?

Tank size depends on your household size and hot water usage. A 6 to 10-gallon tank works for one or two people; 15 to 20 gallons is better for families or frequent showers. Larger tanks take longer to heat but provide more hot water before running out. Consider your typical campground stay length and whether you'll have time to reheat between uses.