Everything You Need to Know About Water Heater Corrosion in Your RV

Posted on: 14 September 2016

While hot water was once a luxury, it has now become a commonplace staple in the average Australian's life. Whether you use your RV for long-term living or short-term trips, you won't want to let your vehicle's water heater fail. That's why it's important to avoid rust or corrosion—one of the biggest killers of hot water tanks. Read on for everything you need to know about RV water heater corrosion and how to solve the issue with a new hot water anode.

What causes water heater corrosion?

Corrosion (known as rusting when iron and iron alloys are the victims) is caused by oxidation. While oxygen is good for humans, it's not so good for metals. A chemical reaction takes place when some metals are exposed to the oxygen in water. This reaction damages the metals, eating away at them slowly until they deteriorate. This process can occur in any setting where metals are oxidised, and it's a very common problem for hot water tanks of all kinds (including those in RVs).

What are the signs of water heater corrosion?

The only way to confirm hot water tank corrosion is to inspect the inside of the water heater. However, one of the typical symptoms that arouses suspicion is rusty or corrosive water, which is usually brown, green or blue in colour and sometimes stains your plumbing. Heavily corroded tanks will also burst or leak. Inspecting the sacrificial anode inside your RV's water heater will give you a good indication of whether or not tank corrosion is present.

What is a sacrificial anode?

A sacrificial anode, also known as a galvanic anode, is a metal alloy rod that prevents water heater corrosion. The anode (which is made from a more active metal) attracts the corroding electrolytes, thereby "sacrificing" itself. When the anode becomes severely corroded, it will stop absorbing damage, causing your water heater itself to corrode. You can inspect the sacrificial anode by turning off your RV's water supply and water pump, relieving the pressure by turning on both water faucets, opening the water heater hatch and using a wrench to remove the rod. 

Do you need a sacrificial anode?

Not all RV water heaters need a hot water anode. Whether or not you need one will depend on your heater brand, which determines the material the tank is made from. As a rule, if your water heater has a steel tank, it needs a sacrificial anode. If the heater is made from aluminium instead, an anode is not needed. Don't be fooled by thinking a glass-lined steel tank is impervious to corrosion—glass itself can be damaged, allowing oxygen to reach the steel underneath. If your RV water heater needs an anode, there should be one present in the tank when you purchase the vehicle.

When and how do you replace a sacrificial anode?

You should perform anode checks (as described above) a few times a year to determine when to replace the rod. It is normal for the anode to be somewhat corroded, but severe corrosion indicates the need for replacement. A severely damaged rod will usually be worn thin, and the core of the rod may be exposed. You can replace the anode by removing it with a wrench, using a pressurised hose to flush debris out of the tank, then putting a new hot water anode in the old one's place. You should check for leaks after turning the water on to ensure the rod is in tightly enough. If you don't feel confident replacing the anode yourself, you can call in a water heater serviceperson with RV experience. For more information, contact local professionals like Carman Heating.