How to replace a caravan hot water heater anode

Replacing the sacrificial anode in your caravan’s hot water system is a straightforward DIY task that usually takes about half an hour. It's a simple procedure, requiring only a few basic tools, so let's get to it...

Many caravans and RVs in Australia use the popular US-made Suburban gas/electric hot water systems. These units require some simple maintenance every six to 12 months, or preferably before any big journey.

Because hot water in hot water systems is slightly corrosive, they come fitted with a sacrificial anode designed to protect the metal inner tank. The anode is made of a softer metal than the tank, like magnesium or aluminium, which redirects the corrosion. As the anode is intended to corrode, periodic inspection is a must, with replacement recommended every 12 months.

A replacement anode is relatively inexpensive; I picked one up from my local big-box outdoor store for $16.99. (I saw one advertised for $13.90 online, but the postage inflated the cost to over $26).

I also splashed out $27 for the Camco hot water tank rinser to assist in flushing the debris out of the tank.

The required tools for the task include a 27mm socket or 1-1/16” tube spanner, some Teflon thread tape, and about a 600mm length of wire to poke around inside the tank to loosen any stubborn debris.

I usually turn off the caravan hot water system the night before to ensure that the water system is cold and ready for the maintenance procedure. I typically perform this task at home in my wash bay next to my workshop, where I have access to mains water pressure, which aids in flushing the debris out of the tank.

Also, as a decent amount of dirty water flows out of the hot water system during the cleaning process, a wash bay provides an ideal location, as cleaning up afterwards is straightforward. I strongly advise against doing this procedure on the driveway in front of your house, as the dirty water can stain or discolour any decorative paving.

For added safety, it’s advisable to follow a few simple steps: disconnect the caravan's 240-volt power, turn off the gas supply at the bottles, switch off the 12-volt water pump, and turn off the main water pressure.

The next step is to turn ‘On’ the taps in the caravan to release any pressure from the caravan water system. Now open the external cover on the hot water system, and open the pressure relief valve on the HWS.

The anode is usually located at the very bottom of the hot water unit. It's easily removed using a 27mm socket or 1-1/16” tube spanner. Be mindful when you remove the old anode, as discoloured water will gush out of the anode (drain) hole. I also use approximately 600mm of stiff wire — an old coat hanger does the trick — to scratch around inside the hot water tank to loosen the debris from the base before inserting the Camco hot water tank rinser.

The Camco rinser is a simple yet effective device engineered to fit into the standard drain opening of caravan hot water tanks. Its primary function is to dislodge and remove the sediment that accumulates over time at the bottom of the tank.

The device comprises a flexible tube with a special nozzle designed to create a high-pressure spray pattern. The rinser attaches to a standard garden hose, while the other end of the rinser, which includes the nozzle, is inserted into the drain opening of the hot water tank after the drain plug or anode rod has been removed.

The high-pressure spray created by the nozzle agitates the sediment and mineral deposits settled at the bottom of the tank. The force of the water breaks up these deposits and flushes them out through the drain opening.

When consistent, clean water flows out of the drain hole, you know the inside of the hot water tanks is now clean.

Now, all you have to do is wrap some Teflon pipe thread tape around the thread of the anode and securely screw the new anode into position.

Inserting the new anode can be tricky for first-timers because the weight of the long shaft tends to tilt the anode downwards, making it difficult to start the thread. It can also prove finicky getting a good grasp of the head of the anode, lining up the thread, and turning it at the same time, so be patient. With a little practice, you’ll easily master this task.

Once the new anode is installed, connect up the mains water. Fill the hot water tank, use the relief valve to purge any air out of the tank, and check for water leaks.  

10 steps for inspecting or replacing the Anode Rod

Before inspecting the anode, ensure your hot water system has been switched off long enough for it to cool down. The water will drain out of the anode hole when you remove the anode.

1) Switch off the HWS and disconnect 240-volt power to the caravan. 

2) Turn off the gas bottles. 

3) Turn off the 12-volt pump. 

4) Disconnect the main pressure water from the caravan. 

5) Turn on your taps to release any pressure. 

6) Open the pressure relief valve. 

7) Remove the anode with a 27mm socket or tube spanner.

8) Flush and rinse the tank. 

9) Install a new anode if needed. 

10) Refill the tank before turning on.

Related: How to replace a hot water heater