RV Water Heater Care: Anode Rods, Flushing and Odours

Most RV water heaters store water in a small tank, usually six to ten gallons, heated by propane, electricity or both. Every time you fill that tank, minerals in the water begin settling out as sediment, and the metal of the tank itself starts a slow chemical battle with the water. Left alone, that battle ends with a corroded tank, and a corroded tank is usually a replacement, not a repair.

The water in and around Calgary tends to be hard, meaning it carries a lot of dissolved calcium and other minerals. Hard water speeds up scale buildup inside the tank, which insulates the heating surfaces, makes the heater work harder and shortens its life. That is why tank flushing matters more here than it does in soft water regions.

The good news is that the two jobs that prevent most of this damage, checking the anode rod and flushing the tank, are simple, cheap and quick once you know what you are doing.

Many RV water heaters use a steel tank protected by a sacrificial anode rod. The rod is made of a metal, usually magnesium or aluminum, that corrodes more readily than the tank walls. Corrosion attacks the rod instead of the tank, which is exactly the point. The rod slowly dissolves so your tank does not.

Because the rod is designed to be consumed, it needs regular inspection. Pull it at least once a year, ideally when you de-winterize in spring. If the rod is more than about three quarters eaten away, or you can see the steel core wire exposed along its length, replace it. Running a steel tank without a working anode rod lets corrosion go straight to the tank itself.

One important note: some RV water heaters use an aluminum lined tank that does not take an anode rod at all, and installing one where it does not belong can cause problems. If you are not sure which type you have, check your owner's manual or ask a technician before buying parts.

Flushing is straightforward. With the heater off and the water cooled, relieve the pressure, remove the drain plug or anode rod, and let the tank empty. What comes out of a neglected tank can be surprising: white and grey mineral chunks, sandy sediment and cloudy water. That material sits on the bottom of the tank, traps heat against the metal and gives bacteria a place to live.

A flushing wand, an inexpensive bent tube that attaches to a garden hose, makes a big difference. Insert it through the drain opening and rinse until the water runs clear. Plan on a full flush at least once a year, and more often if you live in the RV or camp every weekend through an Alberta summer.

When you reinstall the anode rod or drain plug, use fresh thread sealant tape and do not overtighten. A cross threaded drain opening on a water heater tank is an avoidable and expensive mistake.

If your hot water smells like rotten eggs, you are smelling hydrogen sulphide gas. It is produced when naturally occurring bacteria in the water react with the anode rod and sediment in a tank that has been sitting warm and unused, which is common after storage or between trips. The smell is unpleasant but it is also useful information: it tells you the tank needs a flush and a sanitize, not just a shrug.

The fix is usually to drain the tank, flush out the sediment, inspect or replace the anode rod, and sanitize the fresh water system. If the odour keeps returning after proper cleaning, that points to a deeper issue, such as contaminated fresh water tank and lines, a failing rod or persistent bacterial growth that needs a more thorough treatment.

If you are not comfortable pulling the rod, the drain plug will not budge, the tank is weeping water from the fittings, or the smell will not go away, bring the unit to Horton RV Services in Calgary. We can service the water heater, sanitize the system and catch related problems like slow leaks before they damage the surrounding structure.