RV Water Heater Maintenance: Anode Rods, Flushing, and Keeping Your System Running

Most RV owners know their water heater needs occasional attention. Fewer know that the maintenance their water heater actually needs depends entirely on which brand and type they own. Put the wrong procedure on the wrong unit and you can cause more damage than skipping maintenance altogether. Install an anode rod in an Atwood tank during the warranty period and Atwood voids the warranty. Never flush a Suburban tank and the sediment buildup shortens the heater's life and raises your propane costs.

This guide covers all three types of RV water heaters, tank-style Suburban units, tank-style Atwood/Dometic units, and tankless on-demand systems, and explains what each one actually needs, how often, and why.

Know what you have before you do anything else

The single most useful thing you can do before touching your water heater is identify which type you own. The maintenance tasks below are type-specific, and doing the wrong ones is not a neutral outcome.

There are three types of RV water heaters in common use.

Suburban tank-style units have porcelain-lined steel tanks. Because steel corrodes, Suburban protects the tank with a sacrificial anode rod. The anode rod is the defining feature of a Suburban unit and the center of its maintenance routine. Suburban makes both propane-only and dual-fuel (propane plus 120V electric) models in 6, 10, and 12-gallon sizes.

Atwood/Dometic tank-style units have aluminum tanks. Aluminum is naturally corrosion-resistant, which is why Atwood designed their heaters without an anode rod. Atwood was acquired by Dometic, so you may see either name on your unit depending on when your RV was built. The maintenance routine for an Atwood/Dometic tank is similar to a Suburban's in most ways, but the anode rod is absent by design, not an oversight.

Tankless on-demand units have no storage tank at all. They heat water as it flows through a heat exchanger rather than storing it. Tankless units eliminate the anode rod and tank-flushing tasks entirely, but they introduce their own primary maintenance concern: mineral scale buildup inside the heat exchanger.

How to identify your unit from the outside. Open the exterior access panel on the side of your RV. Look at the drain plug at the bottom of the unit. A metal hex head drain plug indicates a Suburban unit with a steel tank. A nylon or plastic hex plug indicates an Atwood/Dometic unit with an aluminum tank. No drain plug at all, or a very compact unit without an obvious tank, indicates a tankless system. If you are still uncertain, the brand name and model number appear on a label inside or around the access panel.

Knowing which unit you have takes thirty seconds and determines everything that follows. When you set up RVKeeper, it asks you to log your water heater brand, type, and model. Every maintenance task it surfaces from that point forward is already filtered to what your specific unit needs, so you are not sorting through anode rod reminders if you have an Atwood or descaling prompts if you have a tank-style unit.

Annual maintenance tasks that apply to all tank-style units

Whether you have a Suburban or an Atwood/Dometic, the following tasks apply to both and should be done at least once per season. If you use your RV frequently or for extended periods, consider doing them twice a year.

Flush and drain the tank

Mineral deposits, sediment, and scale accumulate inside any water heater tank over time. Left in place, they reduce heating efficiency, increase propane or electricity consumption, and shorten the tank's service life. Dometic's own guidance specifies that the tank should be drained and flushed once a year to prevent calcification buildup.

To flush the tank, turn off the water heater and allow it to cool completely. Never drain a hot water heater. The pressure and temperature can cause burns, and the thermal shock of cold water entering a hot tank stresses the tank walls. Allow at least two to three hours after last use before draining.

Turn off the water supply, open a hot water faucet inside the RV to release pressure, then open the drain plug or anode rod port to let the tank drain fully. A flush wand threaded into the drain opening lets you direct fresh water into the tank to rinse out loose sediment before reinstalling the plug. Once drained and rinsed, reinstall the plug snugly, refill the tank, and check for leaks before relighting.

Inspect and clean the burner tube

The burner tube on a propane water heater draws air from outside through the access panel. Dirt, insects, and spider webs accumulate inside the tube over a season and restrict airflow, which causes incomplete combustion, yellow or sooty flame, and in severe cases a fire hazard. This is one of the most consistently overlooked maintenance items on RV water heaters and one of the more consequential ones.

Remove the burner tube access cover and inspect the tube with a flashlight. Clear any debris with a small brush or a can of compressed air. The tube should be clear from end to end with no obstructions at the inlet or the burner orifice.

Inspect the exterior vent and access panel seals

Water intrusion around the water heater access panel causes cabinet rot, corrosion on the exterior components, and in propane units, a hazardous accumulation of fumes. Check the sealant around the cover edges and around the gas line penetration annually. Look for cracking, peeling, or gaps. Reseal any compromised areas with an appropriate RV-grade sealant before the condition worsens.

Test the temperature and pressure relief valve

The T&P valve is a safety device required on all storage water heaters under ANSI Z21.22. It opens automatically if the tank temperature or pressure exceeds safe limits, preventing the catastrophic failure that results from a sealed tank with no pressure release. Because the valve is a safety component, it needs to be confirmed functional, not just assumed to be working.

To test it, lift the lever on the T&P valve briefly to confirm it opens and allows water to flow through the discharge tube. Release it and confirm it closes fully without continuing to drip. A valve that does not open, or one that opens but will not fully reseat, should be replaced. Replacement T&P valves are inexpensive and available at any RV parts supplier.

If your T&P valve weeps water occasionally during normal operation, it does not necessarily mean the valve is faulty. As water heats and expands in a closed system, pressure builds and the valve may release a small amount. This is normal. Continuous dripping or weeping while the heater is off indicates a problem worth investigating.

Suburban-specific maintenance: the anode rod

If you have a Suburban water heater, the anode rod is the most important maintenance item in your routine. Suburban builds their heaters with porcelain-lined steel tanks, and steel corrodes when exposed to water. The anode rod, made of magnesium, provides cathodic protection: through a process of electrolysis, the magnesium rod corrodes in preference to the steel tank. The rod sacrifices itself so the tank does not.

Once the anode rod is fully depleted, electrolysis begins consuming the tank itself. At that point the tank is failing from the inside, and no amount of maintenance reverses the damage.

According to Suburban's own Operation and Maintenance Guide, the anode rod should be inspected and replaced yearly. The guide specifies replacement when consumption or weight loss is greater than 75% of the original material. In areas with high iron content or sulfate in the water supply, the rod can deplete faster and may need more frequent inspection.

How to inspect and replace the anode rod

You will need a 1 and 1/16 inch socket and ratchet, Teflon tape rated for potable water, a bucket, and a replacement rod if the current one is due for replacement. Suburban anode rods use 3/4 inch NPT threads.

Turn off the water heater and allow it to cool completely. Turn off the water supply and open a hot water faucet inside the RV to relieve pressure. The anode rod is located at the drain port at the base of the tank, behind the metal hex head plug you identified earlier. Place a bucket under the opening before removing the rod, as water will drain when you remove it.

Use the socket to break the rod loose. It may be tight if it has been in place for more than a year. Remove it fully and inspect it. If more than 75% of the original material is gone, or if the core wire is exposed, replace it. If the rod still has material remaining, you can reinstall it.

When reinstalling or installing a new rod, wrap the threads with two to three layers of Teflon tape before threading it in. This is the most commonly skipped step and the most common cause of slow leaks at the anode port. Thread the rod in by hand first, then tighten snugly with the socket. Do not overtighten.

Turn the water supply back on, allow the tank to refill fully, and check for leaks at the anode port before relighting the heater.

RVKeeper tracks your last anode rod inspection date and surfaces the annual reminder before the next season, so the interval does not slip through the cracks between trips.

If your Suburban water smells like rotten eggs

A sulfur or rotten egg smell from your hot water is not a service problem. Many water supplies contain enough sulfur to produce the odor, and it is not harmful. Per Suburban's maintenance guidance, the fix is chlorination: add approximately six ounces of common household liquid bleach for every ten gallons of water tank capacity, run the chlorinated water through the system by opening each faucet one at a time until you can smell the chlorine, then let it sit for a day or two before flushing the system thoroughly with fresh water. If the odor returns, repeat the process and replace the anode rod, as a deteriorating rod can contribute to the reaction.

Atwood/Dometic-specific maintenance: what to do instead

If you have an Atwood or Dometic water heater with an aluminum tank, the anode rod procedure above does not apply to you. Atwood designed their tanks with an aluminum interior that provides inherent corrosion resistance. Atwood's own documentation states that they do not recommend the use of an anode rod in their water heaters, and that installing one during the warranty period voids the warranty.

The maintenance routine for an Atwood/Dometic tank focuses on the tasks that do apply: annual flushing per Dometic's guidance, burner tube cleaning, T&P valve testing, and sealant inspection. These are the same general tasks as a Suburban, minus the anode rod.

If your Atwood/Dometic water smells like rotten eggs

The rotten egg odor in an aluminum-tank water heater is caused by hydrogen sulfide produced when sulfur in the water supply reacts with the aluminum lining. The fix is a vinegar flush: drain the tank, mix a solution of four parts white vinegar to two parts water, fill the tank with the solution, let it sit for a few hours, then drain and flush thoroughly with fresh water before returning the heater to service. If the odor persists, a diluted bleach flush followed by a thorough rinse typically eliminates any remaining bacteria contributing to the smell.

Tankless maintenance: descaling and inlet screen cleaning

Tankless water heaters heat water on demand as it passes through a heat exchanger rather than storing it in a tank. The maintenance concerns are entirely different from tank-style units.

The primary failure mode for a tankless water heater is mineral scale buildup inside the heat exchanger. Hard water leaves calcium and magnesium deposits on the heat exchanger coils over time. As scale accumulates, it insulates the coils from the water flowing past them, reducing heat transfer efficiency, lowering output temperature, and eventually causing the unit to overheat and shut down. Left unaddressed, severe scale buildup causes permanent heat exchanger damage.

Descaling frequency depends on your water hardness and how much you use the unit. In areas with very hard water and frequent use, annual descaling is a minimum. In areas with softer water or light use, every two years may be sufficient. The manufacturer's guidance for your specific model is the right reference point.

Descaling a tankless water heater involves circulating a descaling solution, typically diluted white vinegar or a proprietary descaler, through the heat exchanger using a small pump. Most tankless units have service ports that allow this without disassembly. If yours does not, a certified RV technician can perform the service.

The second tankless maintenance task is cleaning the inlet filter screen. Most tankless units have a small mesh filter at the cold water inlet that catches particulate before it enters the heat exchanger. This screen can clog gradually, reducing flow and triggering low-flow shutoff behavior where the heater fails to ignite. Inspect and clean the inlet screen annually. It typically unscrews from the cold water inlet and rinses clean under fresh water.

Because descaling frequency depends on your water hardness and usage patterns, RVKeeper lets you log those conditions when you set up your water heater and adjusts the service reminder accordingly, rather than defaulting to a one-size-fits-all interval.

Signs your water heater needs attention now

A well-maintained water heater gives you reliable hot water throughout its service life without drama. These symptoms indicate something is wrong and should not be ignored until the next season.

Inconsistent hot water or short supply can indicate sediment buildup reducing effective tank volume, a failing heating element in an electric unit, or a depleted anode rod allowing tank degradation to begin.

Discolored or rusty water from the hot tap, particularly in a Suburban unit, is a warning sign that the anode rod has been fully depleted and the tank itself has begun to corrode. Replacing the anode rod and flushing the tank thoroughly may slow further deterioration. If the discoloration is severe or persistent, the tank may need professional evaluation.

Visible corrosion, water stains, or mineral deposits around the exterior access panel, drain plug, or T&P valve discharge tube indicate either a slow leak or chronic weeping that has gone unaddressed. Clean the area, identify the source, and repair or replace the affected component before the corrosion spreads to the cabinet or surrounding structure.

A T&P valve that weeps continuously, even when the heater is off and the water is cold, should be replaced. A valve stuck in the open position is both a water waste and a signal that the valve seat has failed.

Logging what you find during each inspection in RVKeeper gives you a timestamped service history for your water heater. If a symptom recurs or worsens over multiple seasons, that record tells you and any technician exactly what was observed and when, which is considerably more useful than trying to remember.

When these symptoms appear beyond your comfort level to diagnose or repair, a certified RV technician is the right call. Propane systems warrant particular caution. If you smell gas at the water heater, shut off propane at the tank and do not attempt to service the unit yourself.

How RVKeeper tracks this for you

Every task in this guide, from the Suburban anode rod inspection interval to the Atwood annual flush to the tankless descaling schedule, belongs on your complete RV maintenance checklist. These are the jobs that are easy to understand in the moment and easy to forget six months later when your rig has been sitting in storage.

RVKeeper asks you to log your specific water heater brand and model during setup, then builds the maintenance schedule around what your unit actually needs. If you have a Suburban, it tracks your anode rod inspection interval. If you have an Atwood or Dometic, it skips the anode rod and focuses on the maintenance tasks that apply. If you have a tankless unit, it tracks your descaling interval instead.

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