Water Heater Maintenance: The Guide Most Owners Never Get

Most of the San Gabriel Valley draws groundwater that is genuinely hard — dissolved calcium and magnesium that precipitate out when water is heated. In a tank heater that means a layer of sediment on the bottom; the burner then has to heat through rock before it heats water. You'll hear it as popping and rumbling, pay for it as lost efficiency, and eventually see it as an early tank failure. In tankless units the same minerals scale the heat exchanger. Hard water doesn't make either system a bad choice — it makes maintenance non-optional.

Turn the gas control to pilot (or cut power to an electric unit), close the cold inlet, connect a garden hose to the drain valve at the tank's base, run it to a driveway or drain, then open the valve and a hot tap upstairs to let air in. Drain until the water runs clear, close up, refill, and relight. Allow 30–45 minutes. If the drain valve clogs with sediment or the water never clears, stop and call — a tank that hasn't been flushed in years sometimes shouldn't be flushed without a pro on hand, because heavy sediment can be what's plugging small leaks.

A magnesium or aluminum rod threaded into the top of the tank whose entire job is to corrode instead of the tank walls — which is why it's called sacrificial. Once the rod is consumed, the tank itself becomes the anode and starts rusting from the inside. Checking it every 2–3 years and replacing it when it's down to bare core wire is the single cheapest way to extend a tank's life. It's also the first thing we inspect on a water heater service call.

The temperature-and-pressure relief valve on the side or top of the tank is the safety device that prevents dangerous overpressure. Once a year, put a bucket under its discharge pipe and lift the test lever for a few seconds — water should flow, then stop cleanly when you release. If nothing comes out, or it drips continuously afterward, the valve needs replacement. That's a real safety item, not a someday item.

The U.S. Department of Energy recommends 120°F for most households — hot enough for daily use, far less scald risk than factory-common 140°F, slower mineral buildup, and lower standby cost. Households with immune-compromised members or specific dishwasher requirements may have reasons to differ; ask us on your next visit.

• Rusty or metallic-tasting hot water (corrosion inside the tank or fittings).
• Rumbling, popping, or crackling (heavy sediment).
• Moisture or drips around the base — read our repair-or-replace guide before assuming the worst.
• Hot water that runs out noticeably faster than it used to.
• Pilot lights that won't stay lit, or a burner that short-cycles.