Tanked water heaters contain a high volume of water at any given time and the water can contain quite a few minerals. The tank contains an anode rod that attracts those minerals to protect the inner tank walls from mineral buildup, which would cause corrosion and potential leaks over time. An anode rod eventually needs replaced as the rod itself becomes overladen with minerals and can no longer chemically attract new minerals. 

Choosing a new anode rod is often as simple as removing the existing rod, after having drained the water tank, and taking it to the hardware store to match up with an identical replacement. But if you're a new homeowner dealing with a drained and rod-free tank or if you simply want to know your options, there are a couple of tips for finding the right anode rod for your tank.

Note that if the interior of your heater already has corrosion due to the overfull anode rod, you don't want to simply replace the rod. Call a water heater installation company (such as Chambliss Plumbing Company) for a new unit. 

Check the Connection Method

There are two main ways that an anode rod can connect to the tank. A hex head rod has a threaded end that screws up into a grooved hole in the tank. If your tank has a hex nut on the outside, you likely need to buy a hex head anode rod.

The other connection point is through the hot water oulet. An anode rod with a nipple-style end can fit over the outlet. The nipple rods are most often used when a tank needs a backup anode rod or when the original hex rod has been installed so long you can't remove it from the tank.

A third type of anode rods called flexible rod aren't meant to be used on its own the way it looks straight out of the box. The flexible rods come with either a hex or nipple end but then have segmented sections that allow you to easily customize the size of rod needed for your unit. More advanced installers and professional plumbers typically use flexible rods. 

Pick a Metal According to Water Hardness

Anode rods are made of either magnesium or aluminum. Magnesium rods have a stronger current and will work better if you have especially hard or mineral-rich water in your area. On the downside, the magnesium can have a chemically reaction from certain bacteria in the water and produce a sulfur type smell.

Aluminum rods aren't as strong but also pose less risk of causing a sulfur smell. Consider using an aluminum rod if you have normal to soft water and you won't have to worry about frequent rod replacements because the aluminum is overwhelmed with minerals.