How to Start & Use an RV Water Heater

Who among us hasn't suffered through an unintentionally cold shower? There's no sugarcoating the fact that it sucks big time. (Bonus suck points if it happened to be during winter.) I'm a big believer in the fact that camping should be fun and enjoyable, and part of that includes a hot shower at the end of the day. And since you're here asking about RV water heaters, I'll bet anything that's a statement you agree with!

Maybe you haven't actually bought your RV yet, but you're curious how this whole hot water thing works on the road. Or maybe you have bought your RV, but your salesperson went over so much information that day that you don't quite remember the water heater part. How do you turn it on? Can you just, you know, leave it on? And how do you maintain it so it works season after season?

If these questions sound like the ones bouncing around your head, don't worry—we'll go over everything you need to know about your RV water heater, from how to turn it on to how to care for it. Long live hot showers.

In this article:

Using Your Water Heater 101 (Or, Avoiding Cold Showers)

How to Start/Fill a Hot Water Heater in an RV
Can You Leave Your Water Heater on While Camping?
How Long Does it Take for an RV Water Heater to Heat Up?
How Long Does Your Shower Remain Hot?
How Much Propane Does an RV Water Heater Use?

Other Important Info for RV Water Heater Owners:

How (And When) to Drain Your RV Water Heater
Converting to a Tankless Hot Water Heater — Should You Do It?
Troubleshooting: Why is My RV Hot Water Heater Not Working?
How to Clean and Maintain an RV Water Heater
How to Winterize an RV Water Heater

How to Start/Fill a Hot Water Heater in an RV

The first step to using any machine is usually to, well, turn it on. But the thing to remember with an RV water heater is that you only want to turn it on AFTER your hot water tank is full of water (note: this only applies to standard water heaters, not tankless water heaters). Otherwise, you risk burning up the heating element, since water heaters aren't designed to run without water inside the tank.

Generally, these are the steps you should follow to start your water heater after you reach the campsite:

CONNECT TO WATER SOURCE

City water Valve and fresh tank fill on RV

Connect to city water (if you have water hookups) or make sure there is water in your fresh tank (if you don't have hookups). If you're using your fresh tank, turn on the water pump. We want to get things flowin'.

PULL PRESSURE RELIEF VALVE

To make sure your water heater is full, pull your pressure relief valve and let any air escape. Wait until water flows out; when it does, your tank is full.

TURN ON WATER HEATER SWITCH(ES)

Pictured: Exterior switch (top) and interior switch/control panel (bottom)

Now you can turn on the water heater. You might have one, two, or even three switches depending on your heater. Check your interior control panel and turn on your switch there if you have one (you might have two here—one for propane and one for electric). You might also have a switch outside your RV on the water heater itself (it may be hidden behind the heater components). Turn on both the exterior switch and at least one interior switch. You can turn both gas and electric on for a faster warmup time.

If you have an older-model gas water heater, you may have to light the pilot light, but this is rare. (Learn how to light your pilot here.)

TIP: Make sure the bypass valve is closed and your main lines are open, or your hot water tank won't fill up! The bypass valve lets you bypass your water heater when winterizing your camper so that you don't fill it up with antifreeze. It should be closed during the normal season to allow water to flow into the heater. (Read more about winterizing your camper here.)

Diagram; make sure your bypass valve is closed and your main valves are open

Are Water Heaters Gas Or Electric?

Most standard RV water heaters these days have the option to run on both gas and/or electric, so you'll often see two switches on your control panel, one for for each power source. You can even use both simultaneously to heat up your water quicker. (When used alone, propane generally heats up your water quicker than electric does.)

At campgrounds with electric hookups, a lot of campers will briefly turn on both electric and propane to initially heat up the water quickly, then switch to electric only because they've already paid to use the hookup and prefer to save gas. Conversely, when boondocking without an electrical hookup, you'll usually rely on propane only because you won't have unlimited electric power.

RV Water Heater Electric and Gas Switches on Control Panel

Pictured: a control panel switch for a water heater with electric (left) and gas (right) power

Can You Leave Your Water Heater on While Camping?

The next obvious question is—well, what do you do after you turn it on? Do you turn it off after your hot shower or just leave it on for the next time?

You can definitely leave it on while at the campsite so that you have hot water at the ready whenever you want. Many campers choose to do this. Typically the water heater isn't drawing too much electric or propane, so you're not going to save a lot by turning it off between uses.

However, that's not to say you won't save at all. If you're hooked up to campground electric, you don't really need to worry about power consumption. But if you're running off propane and trying to be as conservative as possible, you might choose to turn off the heater between uses (especially overnight when no one's using water). Another reason you might want to turn it off at night is if your heater is particularly loud. Since it will fire up occasionally to keep the water hot, this might be a problem if you're a light sleeper (or if your neighbors complain about the noise). It's usually not much trouble to hit the hot water switch on your way over to make coffee in the morning.

All in all, the choice to turn your water heater off or leave it on is a matter of personal preference.

Also, because a lot of people are worried about burning up their heater if their fresh tank runs out of water (such as while boondocking), I want to assure you that you'll be aware of the empty fresh tank well before your hot water tank runs dry. Your water pump pushes water from the fresh tank into the water heater. So when the fresh water tank runs dry and the pump has nothing left to push through, there will still be leftover water in the hot water tank at the point your water pressure calls it quits.

Of course, if you do choose to leave the heater on, just make sure to turn it off when your trip is over.

How Long Does it Take for an RV Water Heater to Heat Up?

So…how long do you have to wait between flipping that switch and actually getting hot water? It depends on several factors, including:

Whether you use propane, electric, or both simultaneously to power your water heater
How big your hot water tank is (most RV tanks are 6 or 10 gallons. For reference, most homes have 40- or 50-gallon tanks these days)
The outside ambient temperature
The temperature of the water coming in (for instance, if you're using a city water connection that happens to be extra cold, it'll take longer)

On average, though, you can expect your water to heat up in anywhere from 10 to 30 minutes most of the time.

How Long Will the Hot Water Last in Your RV?

Unless you have a tankless heater (more on that below), you won't have unlimited hot water, but if your water heater is functioning properly, it should be able to provide a decent "get in, get clean, get out" shower for at least a single person. If you have a 6-gallon heater and multiple people needing showers, you might need to give it a good twenty minutes in between. With a 10-gallon heater, you might be able to take back to back showers if the first person doesn't dawdle. Your outlook is even better if everyone takes "Navy showers" (ie, Get wet. Turn the water off. Shampoo and soap up. Turn the water on and rinse. Done).

We actually performed a test and monitored an RV shower to see how much hot water we could get in a non-navy-shower capacity. After about 3 minutes and 30 seconds during our trial on a warm fall day, the hot water had cooled to about 76 degrees. (Again, this was not a navy shower, just us letting the water run freely until it got cold.) So there should be enough time to quickly wash up, but not much time for anything else.

Again, this is one of those things you'll have to get a feel for depending on your own usage and habits.

How Much Propane Does an RV Water Heater Use?

This is a difficult question to answer directly, since there are a lot of variables. How hot do you keep the water? Do you have a tankless heater or standard heater (tankless heaters can use up to 50% less propane). Are you using propane only for your water heater (probably not), or other appliances too?

If you're winter camping and heavily relying on your furnace as well as your water heater, you might only get a few days out of your propane tank. However, a family of 3 or 4 people showering every day and using hot water can typically make it a few weeks on a tank during the summer with mild use of other propane appliances like your fridge and stove. The best way to figure out how much propane you use is to just camp, keep track of what you use, and learn to prepare for your specific habits.

How (And When) to Drain Your RV Water Heater

If you're not going to use your RV for weeks (or more) at a time, I recommend draining your water tanks, including your water heater. This is up to every RVer's discretion (some campers choose to only drain at the end of the season, for instance). But just know that leaving stagnant water sit, especially in warmer climates, can result in bacteria growth and a rotten sulfur smell in the water heater tank.

Here's how to drain your hot water tank:

Make sure your water heater is off and your water has had time to cool. Also turn off your water source, pump, and tank power sources (propane or electric).
Pull your pressure release valve to relieve pressure.
Use a wrench or socket to remove your water heater drain plug or anode rod. (You'll have one or the other—a drain plug that comes out alone or an anode attached to the plug. Usually the drain plug style is seen on aluminum Atwood heaters, and the anode style is seen on steel Suburbans.) Tip: a drain valve wrench can make plug removal easier!
Just let the water flow out until the tank is empty.

Want a little more detail? Check out our step-by-step guide here.

Converting to a Tankless Hot Water Heater — Should You Do It?

Now, if you've got a big family (or you just really love your "Hollywood showers" where you can use all the hot water you want), there is another option besides water heater tanks.

On-demand, tankless water heaters are becoming more common on newer RVs. With a tankless heater, you're limited by your power and water supply, not your tank size, because…well, you don't have a tank. As long as you have endless water (such as at a campground with hookups) and enough propane, you and each of your family members can take a Hollywood shower one after the other with no problem (and wash some dishes to boot). No need to space out your showers or heavy-water-use activities.

As far as the downsides to tankless water heaters go, the main one is that you won't quite get instantaneous hot water when you turn on the faucet; it'll take a few seconds to heat up first. A traditional tank might take twenty minutes to heat up, but after that you'll have hot water at the ready until your tank runs out. With many tankless water heaters, you'll have a few seconds of cold water every time you turn on the hot water tap as you wait for the heater to kick in again. There's no storage tank of hot water waiting to be used; it must be heated on demand. (This is both the beauty of tankless heaters and the curse.)

How does this manifest when you're actually camping? Well, you might end up wasting cold water while you wait for it to heat up. For instance, if you don't start washing the dishes until the water runs hot, that's cold water down the drain (literally). It's maybe a few cups each time, but as you can imagine this can add up over several days.

If you're at a campground with hookups, this probably isn't a big deal. But if you're boondocking, wasting water becomes a bigger deal. Showering while boondocking is an even bigger inconvenience with a tankless heater, at least if you go the Navy shower route. Each time you turn the shower on, you'll have a quick spurt of "refreshing" cold water before the hot comes back.

Also note that some heaters do better than others in this regard. My buddy Jake, for instance, speaks highly of his Fogatti heater and has very little "water waste" time.

That said, a lot of RVers love their tankless heaters and would never go back. If you find you run out of hot water too quickly or just hate being limited by the size of your tank, a tankless heater might be for you.

Why Is My RV Water Heater Not Working?

If you ever visit the plumbing section of an RV forum, you'll see miserable campers asking for help in solving their cold water blues. This isn't a guide on troubleshooting your water heater, but oftentimes a "broken" heater is just a result of improper use. This is a good thing, since it means these issues have easy fixes!

If your water isn't heating up, check out these solutions before you do anything else:

Is your bypass valve open? If so, close it until you're ready to winterize. The bypass valve connects your hot and cold water lines. If you leave it open, the hot and cold will mix, and you'll end up with lukewarm water. (This is probably the most common water heater "issue" out there!)
This is another super common mishap. Sometimes you just forget to refill your propane. And if LP is fueling your water heater, no LP = no hot H20.
Are your outdoor shower taps off? If you turn off the outdoor shower head but leave the taps on, the warm and cold water can mix and again, you'll end up with lukewarm water.
Is your pilot light out? Usually this will show up as an error indicator light on your RV's control panel, but you can also visually inspect your heater and note if you don't see the light. Make sure you don't smell any gas that could indicate a gas leak in your rig. If it's all clear, go ahead and relight your pilot light by turning your heater's knob to "pilot" and pressing the igniter button. (If you have a manual pilot, rather than an automatic model, learn how to light your pilot light here.)

If you tried all 4 of these fixes and your heater still isn't working, it's time to take it to the RV doctor (er, shop) to get it checked out.

Make sure the winterization bypass valve is closed and your main lines are open so water can flow into the tank

Pictured: an example diagram of a water heater with a manual pilot light

How to Clean and Maintain an RV Water Heater

Like everything else on your RV, your water heater requires some periodic maintenance to keep it in top shower shape.

Replacing the Anode Rod

Frequency: About 1x per year

Some water heaters, like the popular Suburban brand, have anode rods rather than standard drain plugs. These babies basically take one for the team—they attract corrosive elements that would otherwise attack your tank and act as a protector. You should check your anode rod once a year and replace it once it's about 75% corroded.

To remove an old anode rod, release your tank pressure at the pressure relief valve. Then use a wrench to remove the anode rod from your tank.

Hint: if your anode rod looks like the one on the right, it's time to replace it.

Cleaning the Tank

Frequency: About 2-4x per year

If you use your RV often, I recommend giving your tank a good flushing 2-4 times a year, but at the very least you should do it before you store your RV for the off-season. Just consider it part of the winterization process.

Cleaning your tank is pretty straightforward:

Always turn the heater off and let the water cool first! Turn on a hot water tap in your RV to make sure it's cool before you continue. Also shut off any water sources and power sources (electric and propane) to ensure safe working conditions.
Remove the drain plug or anode rod to empty your tank.
Use a water heater rinser to flush any sediment from the bottom of your tank.

Another yearly maintenance item is descaling your heater to get rid of any mineral buildup. (Calcium is great for your bones, not so much for your water heater.) To descale your tank, complete the steps above, then do the following:

Use a winterization kit to pump white vinegar into the water heater (if you don't have a winterization kit, you can also pump it in via the freshwater tank). Use 2 parts vinegar to 1 part water.
Turn on the water heater and let the hot vinegar sit overnight.
Drain your hot water tank again and flush water through until the vinegar smell dissipates.

For more detail (and to see what came out of our friend Shane's RV the first time he cleaned it), check out our step-by-step guide here.

Using tank rinser to clean RV water heater

Pumping white vinegar into RV water heater with a winterization kit

Pictured: Jake, seen here using a tank rinser to wash out the water tank (top) and pumping vinegar into the tank to clean it (bottom)

How to Winterize a Camper Hot Water Heater

Winterizing your water heater is just one step in winterizing your RV, but it's an important one. Essentially, you'll need to drain your heater and bypass it so that antifreeze doesn't flow into the tank during the winterization process. (It won't damage the tank, but it will waste several gallons of antifreeze.)

Most RVs these days have built-in bypass systems that just require you to flip a switch or lever, but you can also install a water heater bypass kit if you don't have one built in. If you're not sure where your bypass is or if you have one, check your owner's manual.

Learn how to winterize your RV step by step here.

Let the Water Flow

Now you're ready to get out there, live your best life, and enjoy a nice hot shower afterward. Still have questions? Leave them in the comments below!

About Amber S.

As a content writer for etrailer, I might spend my morning loading and unloading a bike on five different bike racks to figure out which is easiest to use. I might be in the parking lot, taking pictures of an impressive RV battery setup our techs came across in the shop and discussing the benefits of the setup with the owner. I might spend an afternoon in a manufacturer training classes for some hands-on experience with new products, and then sit down to assemble all this information into a coherent article.

At etrailer, one of our core values is that we are always learning, and I learn something new every day. I start each morning with the goal in mind of taking all of this information and figuring out the best way to answer the questions people ask us (and the ones they don’t know to ask yet), and helping people get the solutions they need to make their lives easier, safer, and more fun. I’m a DIYer at heart, so it brings me great joy to help a fellow DIYer find what they’re looking for, whether that’s a product, an answer, or a community.