Most water heaters last 8--12 years for tank units and up to 20 for tankless. They rarely fail suddenly -- they give warnings. Knowing what to look for can save you from a basement full of water and the emergency premium that comes with it.
1. It's more than 10 years old
The age of your water heater is the single most predictive factor. Check the serial number on the label -- the first letter typically indicates the month (A=January, B=February, etc.) and the next two digits indicate the year. A tank unit over 10 years old that's showing any other symptom below should be replaced, not repaired.
2. Rusty water
If the hot water from your taps runs discolored -- brownish or orange -- the tank interior is likely corroding. Steel tanks have an anode rod that sacrificially corrodes to protect the tank; once it's depleted, the tank itself starts to go. Rusty water from a water heater usually means replacement is imminent.
3. Water pooling around the base
Moisture around the base of the tank indicates the tank body has cracked or the drain valve is failing. A cracked tank cannot be repaired -- it needs to be replaced. Turn off the water supply and call a plumber the same day.
4. Rumbling or banging noises
As sediment builds up on the bottom of a tank, the heating element has to work through it, causing rumbling, banging, or popping sounds during heating cycles. Heavy sediment reduces efficiency, accelerates corrosion, and can cause the tank to overheat. Flushing the tank can help if caught early; a heavily scaled tank is often better replaced.
5. You're running out of hot water faster
If the first person to shower is using all the hot water, the tank has likely lost capacity due to sediment accumulation or a failed lower heating element. This is often a repair situation if the unit is relatively new, but a replacement situation if the unit is aging.
6. The pressure relief valve keeps discharging
The temperature and pressure relief valve is a safety device that opens if the tank overheats or over-pressurizes. If it's regularly releasing water, something is wrong -- either the valve itself is faulty (a straightforward replacement) or there's a pressure issue in the system that needs diagnosis.
7. Repair estimate exceeds 50% of replacement cost
If a plumber quotes you $700 to repair an 8-year-old water heater and a new unit installed is $1,100, replacing is the better financial decision. You get a full warranty, better efficiency, and aren't spending money on a unit with a limited remaining lifespan.
Bottom line
Don't wait for a water heater failure to call a plumber. If your unit is showing any of these signs, get a quote for replacement -- the cost of a flooded basement, water damage remediation, and emergency dispatch will far exceed the cost of proactive replacement.
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