Safety first: Your RV water heater uses propane (LP gas), 120-volt electricity and very hot water under pressure. Always follow your water heater’s manual and your RV owner’s manual, read every label warning, and turn off the propane and electric power before you work on it. Let the water cool before you open the drain, because it can scald. If you smell propane, can’t light the burner, or aren’t fully confident with a job, use a qualified RV technician. See our full disclaimer at the end of this article.
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Most RV water heaters are small tanks of 6 to 16 gallons that heat water with propane, electricity, or both. Turn the heater on only when the tank is full of water, use the electric setting at campgrounds with hookups to save propane, and check the tank every year: a quick flush, a look at the anode rod (if your heater has one), and a test of the pressure relief valve. Before cold weather, bypass and drain the tank so it can’t freeze and crack.
This guide explains how RV water heaters work, the difference between tank and tankless models, how to use yours, and the simple yearly maintenance that keeps the hot water coming.
How an RV Water Heater Works
An RV water heater sits behind a small access door on the outside wall of your RV. Cold water from your fresh water tank or the campground hookup flows into it, gets heated, and goes out to your faucets (taps) and shower.
Most RV water heaters can use one or more of these heat sources:
- Propane (LP gas): a small burner under the tank heats the water. It works anywhere, including when you camp without hookups (boondocking). Newer models light themselves with direct spark ignition (DSI), so you just flip a switch inside the RV. Older models have a pilot light you light by hand at the outside door.
- Electric: a heating element inside the tank runs on 120-volt power from a campground hookup or a generator. A common size is 1,440 watts, which draws about 12 amps. It heats more slowly than propane but saves your propane for when you need it.
- Engine heat: some motorhomes have a heat exchanger (Suburban calls its version “Motoaid”) that uses hot engine coolant to warm the tank while you drive, so you arrive with hot water.
Many heaters have both propane and electric. You can run both together for the fastest heat-up, then switch to electric only to keep the water hot at a campground.
Tank vs Tankless RV Water Heaters
| Tank water heater | Tankless (on-demand) water heater | |
|---|---|---|
| How it heats | Keeps 6 to 16 gallons hot and ready | Heats water only as it flows through |
| Fuel | Propane, electric, or both | Mostly propane; some models also have an electric option |
| Hot water supply | Runs out when the tank is used up, then needs time to reheat | Keeps going as long as you have water and propane |
| Upfront cost | Lower | Higher |
| Good to know | Simple and familiar; needs yearly flushing | Needs good water flow to fire up; can be fussy with low pressure |
Tank water heaters
Tank heaters are the most common type and come in sizes from about 4 to 16 gallons, with 6 and 10 gallons found in most RVs. The two names you’ll see most often are Suburban and Atwood (now made by Dometic). The main difference for owners is the tank itself:
- Suburban tanks are steel with a porcelain lining, and they use a replaceable anode rod. This metal rod slowly corrodes on purpose, so the tank doesn’t. It also works as the drain plug.
- Atwood/Dometic tanks are aluminum with a protective lining built in, so they don’t use an anode rod. They have a plain plastic drain plug. Don’t add an anode rod to one of these tanks; check your manual if you’re unsure.
Not sure which you have? Open the outside access door and look for the brand label, or check your RV owner’s manual.
Tankless water heaters
Tankless models such as the Truma AquaGo, Girard, Furrion and Suburban tankless heaters warm the water only while a faucet is open, so you don’t run out halfway through a shower. Some are designed to fit the same wall opening as an old tank heater. The trade-offs are a higher price, the need for steady water pressure (some won’t light at a low trickle), and, in some models, a short wait or temperature swings while the burner adjusts. They suit RVers who shower often, camp with family, or want to avoid waiting for a tank to reheat.
Should You Upgrade Your RV Water Heater?
Ask yourself a few questions before you buy:
- Do you run out of hot water often? A larger tank or a tankless heater may help. If not, keeping your current heater in good shape is usually the better value.
- Does your current heater have electric? If it’s propane only and you camp at full hookups, a model with an electric element (or an add-on electric kit) saves propane.
- Will it fit? Measure the wall opening and check the replacement’s cut-out size, gas and water connections, and power needs before you order.
- Who will install it? Replacing a water heater means working with propane lines, electrical wiring and the sidewall seal. Unless you have experience with gas and electrical work, have a qualified RV technician do it.
If you’re replacing a 6-gallon tank heater, the Suburban SW6D 6-gallon RV water heater is a widely used model. It runs on propane with direct spark ignition; if you also want electric heating, look for the SW6DE version. Check that the size, wall cut-out and connections match your current heater before you buy.
How to Use Your RV Water Heater
- 1. Fill the tank first. Connect to water (or turn on the water pump), make sure the bypass valves are set to “normal” (not bypass), then open a hot faucet and let it run until water flows steadily with no spitting air. Now the tank is full.
- 2. Turn on propane, electric or both. Use the water heater switch inside the RV (or light the pilot by following the instructions on the heater label). Check that your propane tank valve is open.
- 3. Give it time. A 6-gallon tank on propane is usually ready in roughly 20 to 30 minutes; electric alone takes longer. Times vary with the tank size and how cold the water is.
- 4. Turn it off when you leave or drain. Switch off the electric element before you drain the tank, and turn off the propane before refueling or entering a tunnel or ferry that bans open flames.
Never turn on the electric element with an empty tank. Heating with no water inside (“dry firing”) can burn out the element within minutes. This is the most common way RVers damage their water heater, usually after draining it and forgetting the switch is on.
Yearly RV Water Heater Maintenance
Your water heater needs a little care once a year, more often if you camp full time or in areas with hard water. Always follow the schedule in your water heater’s manual.
1. Drain and flush the tank
Minerals and sediment settle at the bottom of the tank over time. They make the heater work harder, can cause a rumbling or popping sound, and may give the water an odor.
- Turn off the propane and the electric element, and let the water cool.
- Turn off the water supply (city water and the water pump).
- Open a hot faucet inside the RV and lift the lever on the pressure relief valve to release pressure.
- Remove the drain plug or anode rod at the outside access door and let the tank empty.
- Use a tank rinser wand on a hose to spray out loose sediment until the water runs clear.
A tank rinser wand makes this much easier, and Suburban owners will need a 1-1/16 inch deep socket to remove the anode rod.
2. Check the anode rod (Suburban heaters)
When you remove a Suburban anode rod, look at how much metal is left. Suburban’s guidance is to replace it when it is heavily pitted or worn down to about 1/4 inch thick, or “mostly eaten away.” Wrap the threads of the new rod with plumber’s tape before you screw it in, and use a rod made for your heater. A Suburban magnesium anode rod costs far less than a new tank.
3. Test the pressure relief valve
The pressure relief valve near the top of the heater lets out water if the pressure or temperature gets too high. Once a year, with the tank full and pressurized, carefully lift the lever for a moment so a little water flows out, then let it snap shut. Point your face and hands away, because the water may be hot.
A few drips while heating are often normal. As water heats, it expands. Tank heaters are designed to keep a small air pocket at the top to absorb this. If the valve drips a lot, turn off the heater and water supply, open a hot faucet, and lift the relief valve lever until water stops flowing. When you refill, a new air pocket forms. If the valve keeps dripping or sprays very hot water, have a technician check it. Never plug or remove the relief valve.
4. Keep the burner area clean
Insects such as mud daubers and spiders like to build nests in the burner tube, which can block the flame. Look inside the access door and burner tube each spring. A screen made for your RV’s water heater vent helps keep them out, but it must not block air flow.
Winterizing and Storing Your Water Heater
Water left in the tank can freeze, expand and crack it. Before freezing weather or long storage:
- Turn off the propane and electric to the water heater, and let the water cool.
- Drain the tank as described above, and leave the drain plug or anode rod out while it drains fully.
- Set the bypass valves to “bypass.” This keeps RV antifreeze out of the water heater, so you don’t waste several gallons filling the tank with it. If a bypass valve in your RV leaks or sticks, a brass 3-way bypass valve is a common replacement. If your RV has no bypass at all, a permanent water heater bypass kit can be added. Fitting one means cutting into the water lines behind the heater, so ask an RV technician if you aren’t comfortable with plumbing.
- Finish winterizing the rest of your plumbing using your RV manual’s steps. Our RV maintenance checklist by season covers the full process.
About RV antifreeze: RV antifreeze is not for drinking, even though it’s made for water lines. Follow the label warnings and store it securely, away from children and pets. Flush the lines with fresh water before you use them again.
In spring, put the drain plug or anode rod back in, set the bypass valves back to “normal,” and fill the tank with water before turning on the heater.
Common RV Water Heater Problems
| Problem | Likely causes | What to try |
|---|---|---|
| No hot water on propane | Propane tank empty or valve closed; air in a new gas line; burner tube blocked | Check the propane level and valve; try lighting a stove burner first to purge air; look for nests in the burner tube |
| No hot water on electric | Switch off; tripped breaker or reset button; burnt-out element (often after dry firing) | Check the switch, the breaker panel and the heater’s reset button; have the element tested if it still won’t heat |
| Rotten-egg smell | Bacteria reacting with the anode rod or sediment | Drain and flush the tank; follow the maker’s sanitizing steps |
| Relief valve dripping | Missing air pocket; pressure too high | Restore the air pocket (see above); use a water pressure regulator at the campground |
| Popping or rumbling sound | Sediment on the tank bottom | Drain and flush with a tank rinser |
If you smell propane at any time, turn off the propane at the tank, don’t use switches or flames, get everyone out, and call a qualified RV technician.
Campground water pressure can also strain your water heater and plumbing. A water pressure regulator is one of the first upgrades we recommend in our best motorhome upgrades guide.
RV Water Heater Questions
How long does an RV water heater take to heat up?
A typical 6-gallon tank takes roughly 20 to 30 minutes on propane, and longer on electric alone. Using both at once is fastest. Check your heater’s manual for its recovery time.
How long does hot water last in an RV?
A 6-gallon tank gives enough for a short shower, especially with a low-flow showerhead. Turn the water off while you soap up, and allow time between showers for the tank to reheat.
Can I leave my RV water heater on all the time?
Many RVers leave it on electric at a full-hookup campground, and that’s fine as long as the tank is full. Turn it off before you drain, travel through areas that ban open flames, or store the RV.
Do all RV water heaters have an anode rod?
No. Suburban steel tanks use one. Atwood/Dometic aluminum tanks don’t and shouldn’t have one added. Tankless heaters don’t have a tank, so there’s no anode rod.
Should I drain my RV water heater between trips?
For short breaks in mild weather it isn’t necessary, but draining helps an anode rod last longer and keeps the water fresher. Always drain it before freezing weather or long storage.
Related Guides
- The essential RV maintenance checklist by season
- Winter RV camping tips
- Best motorhome upgrades: 10 worth doing
- RV safety tips: how to stay safe on the road and at camp
- 30 amp vs 50 amp RV
Acronyms Used in This Article
- DSI: direct spark ignition
- LP: liquefied petroleum (propane)
- RV: recreational vehicle
Disclaimer
The information provided is for educational purposes only. Before carrying out any maintenance or safety task on your RV, please do your own further research so you are fully confident in each step. If you are ever unsure, consult a qualified RV professional or get a second opinion. Readers are responsible for their own safety, and PreciousRV.com accepts no liability for any injury, loss or damage. As an Amazon Associate, we earn from qualifying purchases. Facts checked in November 2026.
Featured photo: p_x_g on Flickr, CC BY 2.0, cropped.
