What the anode rod does
A water heater tank is steel with a glass lining. No lining is perfect, and where the water touches bare steel, it corrodes. The anode rod, usually screwed into the top of the tank, is made of a metal that corrodes more readily than steel. As long as it has metal left, corrosion goes to the anode rather than the tank. It is sacrificial by design.
Once the anode is mostly gone, the steel has no protection, and the tank begins to corrode from the inside. That ends, eventually, in a leak from the shell. Checking the anode and replacing it before it is spent is one of the few genuinely preventive jobs on a tank.
Signs the anode needs attention
- Rusty or discoloured hot water while the cold runs clear
- A sulphur or rotten-egg smell from the hot tap only
- A tank that has never had its anode checked
- A well-water home where anodes are known to wear quickly
Often there are no signs at all until the anode is gone. That is why checking it on a schedule, rather than waiting for symptoms, makes sense.
On a private well?
Why wells use up anodes faster
Some well water is more aggressive toward metal than town water, so the anode wears faster. And in some well homes, the anode reacts with the water in a way that produces a sulphur-like smell in the hot water only. Both are reasons to check the anode more often on a well, and sometimes to choose a different type of anode.
Anodes on wells are worth checking more often.
Types of anode
Anodes come in different metals and forms, and the right one depends on the water and the problem. Standard rods suit many homes. Where hot-water-only odour is an issue, a technician may suggest a different type of anode. Powered anodes, which use a small electrical current instead of a sacrificial metal, are another option in some situations. Segmented or flexible anodes come in linked sections so they can be fitted where there is not enough headroom above the tank for a solid rod, which is common in low Connecticut cellars.
The technician will explain which suits your tank and water. Some tanks have their anode combined with the hot outlet fitting, which affects how it is replaced.
Why this is not a DIY job
- The tank must be isolated and depressurised first
- Anodes are often seized and need significant force to remove
- Too much force can damage the tank fitting
- Fuel, electrical and relief valve connections are nearby
How replacement is done
The technician shuts off the water to the heater, relieves pressure, and drains a little water from the tank. They remove the old anode, often with a long-handled wrench and sometimes an impact tool, and inspect it: how much is left says a lot about the tank's condition. The new anode goes in with fresh thread sealant, the tank is refilled and purged of air, and the heater is brought back into service. If the anode shows the tank has been unprotected for a long time, the technician will say so, since it may affect whether the tank is worth keeping.
The anode and the work are priced first.
What a spent anode looks like
A new anode is a smooth, even rod. As it works, it pits and thins, often unevenly, and in places the steel core wire inside it becomes exposed. A rod that is thin and pitted along much of its length, or down to bare wire in sections, has little protection left to give. A rod that is still substantial means the tank has been well protected and the next check can wait longer. Technicians often show homeowners the old rod, because it says more about the water and the tank than any description can.
An anode that has vanished almost entirely is a warning about the tank rather than just the rod. It means the steel has been unprotected for some time, and a new anode may be buying less time than it would on a younger tank.
Anodes and hot-water odour
In some homes, especially on well water, the standard anode reacts with what is in the water and produces a sulphur-like smell in the hot water only. The usual response at the heater is to change the type of anode, and sometimes to flush the tank at the same time. It is not a guarantee, because water varies, and removing an anode entirely is not an option: it would leave the tank unprotected. If a smell comes back after an anode change, the technician can talk through other approaches at the heater. Questions about the water itself belong with a water professional.
When the anode is part of the hot outlet
Some tanks do not have a separate anode port. Instead, the anode is built into the fitting where hot water leaves the tank. Replacing it means disconnecting the hot outlet, which is a slightly bigger job and one more reason to leave it to the technician. The technician will know from the model whether your tank is built this way.
What affects the cost of anode rod replacement
- The type of anode chosen
- How seized the old anode is
- Headroom above the tank, and whether a segmented anode is needed
- Whether a flush is done at the same visit
How long anode rod replacement takes in Connecticut
Anode replacement is usually a short part of a single visit, longer when the old rod is badly seized or headroom is tight. The heater is back in service once refilled.
Anode rod questions
How often should the anode rod be checked?
It depends on your water. On town water, less often; on some wells, much more often. After a first check, the technician can suggest an interval based on how worn the anode was.
Can replacing the anode stop a rotten-egg smell?
Often it helps a lot, particularly when switching to a different type of anode. It depends on your water. The technician will explain what to expect.
My cellar ceiling is low. Can the anode still be replaced?
Usually, using a segmented or flexible anode that goes in section by section. Mention the headroom when you call.
Is it worth replacing the anode on an old tank?
If the tank is still sound and the anode is spent, it can help. If the tank has been unprotected for years and shows corrosion, the money may be better put toward a replacement. The technician will advise.
Do tankless units have anodes?
No. Tankless units do not have a storage tank to protect. Their maintenance is descaling instead.
Do indirect tanks have anodes?
Some do and some do not, depending on how the tank is built. The technician can tell you what applies to yours.
What does the old anode tell you?
How fast your water is using up the protection. A thin, pitted rod after a short time suggests more frequent checks; a rod that is still substantial suggests a longer interval.
Can I replace the anode myself?
We recommend a technician. It involves a tank under pressure and often a seized rod that needs real force, with a risk of damaging the tank fitting.
Will the tank need to be drained to change the anode?
Only partly. The technician shuts off the water, relieves pressure and drains a little water so the anode can be removed without spilling. The tank is then refilled and returned to service.
Can an anode be added to a tank that never had one?
Almost every glass-lined steel tank is built with an anode. If you are unsure whether yours has one or where it is, the technician can tell you from the model.