In many Washington homes, the water heater is the first place hard water shows up in a way you can see and hear. Most storage tank heaters also have a less visible part worth checking: the anode rod. It is a long metal rod, usually screwed into the top of the tank, that corrodes on purpose so the steel tank around it corrodes more slowly. Once the rod is used up, the tank has no sacrificial protection left.
What the rod is made of
Anode rods are commonly made of magnesium, aluminum, or zinc, sometimes with other metals mixed in. Magnesium rods work well in many water conditions, but aluminum or zinc alloy rods are often recommended where a sulfur smell has been a problem. The material is usually stamped on the top cap or the rod itself. If you cannot find it, look more closely before you assume the rod is fine.
Hard water and the tank
Very hard tap water leaves mineral scale inside the tank as well as on the heating element. That scale is not the same as anode corrosion, but both can show up during the same inspection. A thick crust on the lower tank, or a rod buried in hardened deposits, suggests the water has been working on the tank for a long time and the rod may have been losing ground for a while.
Checking the rod safely
Take these steps in order. Do not skip the power and water shutoffs.
- Turn off the power at the breaker, or set a gas unit to its pilot setting.
- Shut off the cold water supply valve at the top of the heater.
- Open a hot tap somewhere in the house to ease the pressure.
- Attach a hose to the drain valve and drain enough water to lower the level below the rod fitting.
- Loosen the rod with a socket wrench. A long rod may need a longer breaker bar, and an old fitting may be seized.
If the fitting will not move, stop. Do not force it, and do not use a torch on the tank or fittings. A stuck rod is a job for a licensed professional.
What to look for
- Bare core wire showing through the outer coating at the top of the rod
- A thin, pitted, or flaking rod with much of its material gone
- A heavy mineral or calcium crust covering most of the rod
- A rod that is split, broken, or loose at the top
- A rod that still looks thick and firm, with the date noted so you can check it again later
A sulfur smell from hot water
If the hot water smells like rotten eggs but the cold water does not, a worn magnesium rod can be part of the picture. Sulfate in the water and bacteria in the tank can react with some anode materials and produce a sulfur odor. This is a common cause to check, but it is not the only one. Rotten egg smell in a private well has its own set of causes, so test the water before deciding what the smell means. Testing tells you more than guessing from the tank.
When replacement makes sense
Replace the rod when the core wire shows, when most of the rod is gone, or when the smell continues after the tank has been flushed and a different rod material has been fitted. Swapping a rod is a simple job for many homeowners, but bring in a licensed professional if the tank is leaking, the fitting is stripped, or gas controls are involved. When you reinstall, use thread sealant suited to water heater fittings and check for leaks once the water is back on.
Keep a simple record
Write the date of each check on the tank or in a notebook kept near the water heater. Anode rods wear on their own schedule, which depends on the water and the heater, so a dated note is the simplest way to know when the next check is due. If you also test your water for hardness and sulfate, keep those results with the same record. Over time, the notes will show whether your Washington water is wearing the rod faster than expected.