Tank Corrosion: What Causes It and How to Fix It in Home Appliances

If you’ve ever seen rust inside a water heater or noticed a strange smell from your fridge, you’re probably dealing with tank corrosion. It’s a common problem that can turn a perfectly good appliance into a costly replacement if you ignore it.

Why Tank Corrosion Happens

Most appliances that store water – water heaters, boilers, refrigerators, and even some washing machines – have metal tanks that sit inside a plastic or metal shell. Over time, moisture, minerals and chemicals seep into the metal and start a slow rusting process. Hard water is a big culprit because the mineral buildup creates tiny pits where rust can begin. Leaking seals or a cracked tank let air in, speeding up oxidation. In older models, the protective coating inside the tank may wear away, leaving the metal exposed.

Temperature also matters. Hot water accelerates corrosion, which is why water heaters and boilers are especially vulnerable. On the flip side, cold appliances like fridges can develop corrosion if the drain pan fills with water and doesn’t evaporate properly.

How to Spot and Deal With Tank Corrosion

First signs are usually visual – you might see rust stains on the outside of the tank or hear a metallic clunk when the appliance runs. A foul, metallic odor from hot water is another red flag. If you notice water pooling around the base of a fridge or a boiler, check the sump for rust-colored water.

When you suspect corrosion, turn off the appliance and shut off the power or gas before you start. For a water heater, drain the tank completely: attach a garden hose to the drain valve, open a hot‑water faucet nearby, and let the water flow out. Inspect the interior wall; if you see widespread rust, it’s probably time for a replacement tank or a professional rebuild.

Sometimes a simple fix works. In a fridge, clean the drain pan with a mixture of warm water and a splash of vinegar, then dry it thoroughly. Replace any cracked gaskets to keep moisture out. For boilers, flush the system annually with a descaling solution to remove mineral buildup that fuels rust.

If the corrosion is limited to a small spot, you can use a rust‑inhibiting paint designed for interior tank surfaces. Follow the product instructions carefully, and make sure the tank is completely dry before re‑filling it.

Regular maintenance beats emergency repairs every time. Set a reminder to check your water heater’s anode rod once a year – the rod attracts corrosion and protects the tank. Replace the rod when it looks corroded. Keep an eye on water hardness; a simple water softener can cut down mineral deposits and extend the life of your tanks.

Don’t wait until you’re left with no hot water in the middle of winter. A quick visual check, a few preventive steps, and timely professional help can keep tank corrosion at bay and save you money.