Water heaters are where water quality and plumbing meet, and it's the appliance hard water kills first. Scale settles on the bottom of a tank and insulates the burner from the water, so the burner runs longer and hotter to hit the same temperature — you pay for the wasted fuel and the tank fails years early. On an electric heater the scale forms directly on the elements and burns them out. If you're replacing water heaters more often than every decade, the water is usually the reason.
Tank vs. tankless vs. indirect
Conventional tank. Lowest install cost, simplest to service, and a known quantity. You're limited to what's in the tank and you pay to keep it hot around the clock. Typically 10–12 years, less on untreated hard water.
Tankless. Heats on demand, never runs out, lasts closer to 20 years and takes up wall space instead of floor space. Costs more up front, usually needs a larger gas line and new venting, and needs annual descaling — non-negotiable on hard water. Worth it if you're running out of hot water now or you want the space back.
Indirect-fired. If you already have a boiler, an indirect tank uses it to heat a well-insulated storage tank. Very efficient during heating season, no separate burner or flue, and often the cheapest hot water in the house. Only makes sense with a boiler already in place.
The maintenance almost nobody does
- Anode rod. A sacrificial metal rod that corrodes so your tank doesn't. It's consumable. Checked every few years and replaced when it's spent, it can double the life of a tank — and it's also the fix for rotten-egg hot water.
- Annual flush. Drains the sediment that's insulating your burner. Ten minutes of work that pays for itself.
- Expansion tank. Required on a closed system. Without one, heated water has nowhere to expand and pressure spikes stress the tank, the relief valve and every fixture in the house.
- Mixing valve. Lets you store water at 140°F — hot enough to suppress legionella — while delivering a safe 120°F at the tap. It also effectively increases usable capacity.
- Check the relief valve. A T&P valve that's seized is a real safety problem, and it's a thirty-second check.