How to Tell If a Water Heater Is Worth Repairing

Here's how to read the situation clearly and make the right call.

Start With the Age of the Unit

The first thing to check isn't the symptom – it's the age. Water heaters have a well-documented lifespan, and age determines whether a repair is worth investing in at all. A tank water heater (the standard kind with a big cylindrical tank) typically lasts 8 to 12 years. Tankless water heaters last longer, often 15 to 20 years with proper maintenance.

You can find the manufacture date on the unit's serial number label, usually on a sticker near the top of the tank. The first four characters of the serial number typically encode the manufacture date, though the format varies by brand – Bradford White, Rheem, A.O. Smith, and others each use slightly different coding. A quick search for "[brand name] water heater serial number date code" will decode it in under a minute.

If your unit is under 6 years old, almost any repair short of a cracked tank is worth doing. If it's 10 years or older, you need a much more compelling reason to repair rather than replace. Spending $400 to repair an 11-year-old water heater that might fail completely within 18 months is rarely the smart play.

The Problems That Are Worth Fixing

Some water heater issues are straightforward repairs that cost relatively little and extend the life of a unit that still has good years ahead of it.

Pilot Light Won't Stay Lit (Gas Water Heaters)

If you have a gas water heater and the pilot light keeps going out, the most common culprit is a faulty thermocouple – a small safety device that senses whether the pilot flame is burning and cuts the gas supply if it goes out. Thermocouples wear out over time and are one of the most common water heater repairs. The part itself costs $10 to $20 at any hardware store, and replacing it is a straightforward DIY job for anyone comfortable with basic plumbing and gas appliances. If you're not comfortable with gas lines, a plumber can handle it in under an hour for $75 to $150 in labor. This repair is almost always worth doing on a unit under 10 years old.

No Hot Water From an Electric Heater

Electric water heaters use one or two heating elements (upper and lower) to heat the water. When you're getting no hot water at all, or only a small amount before it runs cold, a failed heating element is the most likely cause. Elements are inexpensive – typically $15 to $30 – and replacing one is a manageable DIY project if you're comfortable turning off the power at the breaker and following instructions carefully. Even with a plumber doing the work, this repair usually runs $150 to $300 total. On a unit under 8 years old, it's a clear repair-not-replace situation.

Inadequate Hot Water

If the water runs warm but not hot, or runs out faster than it used to, the issue is often a faulty thermostat rather than a failing tank. On both gas and electric heaters, the thermostat controls the target water temperature and can fail or drift over time. Thermostat replacement is inexpensive (the part is usually under $25) and is worth doing before assuming the tank itself has a problem. Also worth checking: the temperature setting itself. Someone may have adjusted it, or the recommended setting (120°F / 49°C) may have drifted. This takes 30 seconds to check and sometimes solves the problem entirely.

Pressure Relief Valve Leaking

The temperature and pressure relief (TPR) valve is a safety device that releases pressure if the tank gets too hot or pressure builds too high. If it's dripping or releasing water, it needs attention – but this doesn't necessarily mean the tank is failing. TPR valves can fail simply from age and mineral buildup. The valve itself costs $10 to $30 and can be replaced DIY with basic plumbing skills. However, a TPR valve that's releasing water frequently may also indicate that the water temperature or pressure in your home is set too high, which is a separate issue worth investigating.

Safety note: Never plug, cap, or ignore a leaking TPR valve. It's a safety device. If it's releasing water repeatedly even after replacement, have a plumber check your system pressure and thermostat settings.

Sediment Buildup Causing Rumbling Noises

If your water heater rumbles, pops, or makes cracking sounds during heating cycles, sediment has built up on the bottom of the tank. This happens naturally over time as minerals in the water supply settle and harden. Heavy sediment reduces efficiency, forces the tank to work harder, and can shorten its lifespan. The fix is a full tank flush – draining the tank completely to remove the sediment. This is a DIY-accessible job that takes about an hour and requires only a garden hose and a flathead screwdriver. If you haven't been flushing the tank annually (a standard maintenance task), doing so now can noticeably improve performance and extend the unit's life. On a relatively young tank (under 7 years), this repair is nearly always worth doing.

The Problems That Usually Mean Replace

Some situations are clear signals that repair doesn't make economic or practical sense.

The Tank Is Leaking

A leaking tank is almost always a replacement situation. Once the steel tank itself is corroding and leaking, there's no effective repair. The corrosion that causes leaks is typically internal and progressive – even if you could stop one leak, the tank wall is compromised and more failure is coming. Before you panic, confirm the leak is actually coming from the tank itself rather than from a fitting, valve, or connection at the top or bottom of the unit. Fittings and connections can be tightened or replaced; the tank cannot. Get down with a flashlight and locate the exact source of the water. If it's seeping from the tank body itself, start shopping for a replacement.

The Unit Is Old and Multiple Things Are Failing

If your water heater is 10 or more years old and you're looking at multiple concurrent issues – a failing element, a corroded anode rod, sediment buildup, and a leaking valve all at once – the repair math almost never adds up. Each repair extends the life of an aging unit that's approaching the end of its natural lifespan anyway. You're better off applying that money toward a new unit with a warranty and years of reliable service ahead of it.

Repair Cost Exceeds the 50% Rule

A useful rule of thumb for any appliance: if the repair cost exceeds 50% of the cost of a new unit of similar quality, replacement is generally the better investment. A new tank water heater (40–50 gallon, installed) typically runs $900 to $1,500 depending on your location and the unit. If a repair is going to run $600 or more on a unit that's already 8 to 10 years old, the economics are telling you something.

Rust-Colored or Metallic-Tasting Hot Water

Rusty or metallic-tasting hot water – specifically from the hot water tap only – typically indicates that the inside of the tank is corroding. The anode rod (a sacrificial magnesium or aluminum rod that protects the tank from corrosion) may have been depleted without being replaced, allowing the tank itself to rust. On a relatively new unit (under 6 years), a new anode rod plus a flush may help. On an older unit, internal corrosion is a sign that the tank's useful life is ending. If you're consistently seeing rust-colored water from the hot tap, have a plumber assess whether the tank is salvageable before spending money on parts.

The Repair vs. Replace Decision at a Glance

Rather than a strict formula, think about it this way: the younger the unit and the simpler the problem, the stronger the case for repair. As the unit ages and the problems multiply, the balance tips toward replacement.

A 4-year-old water heater with a failed thermocouple? Fix it without question. A 10-year-old unit with a leaking tank, sediment buildup, and failing elements? Replace it, and consider upgrading to a tankless or heat pump water heater while you're at it.

When the decision is genuinely close – an 8-year-old unit with a $300 repair on a non-tank problem – it's worth getting a plumber's honest opinion. Ask them directly: "If this were your house, would you repair it or replace it?" A good plumber who isn't motivated by the installation sale will give you a straight answer.

When to Call a Professional

Most of the diagnostic steps above are things you can do yourself with a flashlight and 20 minutes. But water heater repair crosses into professional territory in a few situations. If you have a gas water heater and the issue involves anything beyond the pilot light or thermocouple – gas valves, burner assemblies, venting – call a plumber or licensed gas technician. Gas line work is not DIY territory.

Similarly, if you're not comfortable shutting off power at the breaker and handling electrical components, heating element replacement is better left to a pro. And any time you suspect a gas leak (you'll smell sulfur or rotten eggs), shut off the gas supply immediately, leave the house, and call your gas utility before doing anything else.

FAQ

How long does a water heater repair typically take? Most straightforward repairs – thermocouple replacement, heating element swap, thermostat replacement – take one to three hours. A full sediment flush takes about an hour. More complex jobs involving pressure valves or gas components may take longer, especially if parts need to be ordered.

Can I do water heater repairs myself? Many basic repairs are well within DIY range for someone comfortable with simple plumbing and home systems. Thermocouple replacement, tank flushing, thermostat adjustment, and TPR valve replacement are all considered beginner to intermediate DIY tasks. Any repair involving gas lines or extensive electrical work should go to a licensed professional.

What's the most important thing I can do to extend my water heater's life? Flush the tank annually to remove sediment, and replace the anode rod every 3 to 5 years (or every 2 years in areas with hard water). These two maintenance tasks alone can add years to a tank water heater's lifespan. Most homeowners skip both, which is a big part of why units fail earlier than they should.

Is a tankless water heater worth the upgrade? If you're already replacing a tank unit, a tankless water heater is worth serious consideration. They last significantly longer (15–20 years), take up less space, and provide endless hot water on demand rather than running out. The upfront cost is higher ($1,000–$2,500 installed depending on fuel type), but the lifespan and efficiency advantages often justify it over the long run, especially in households with high hot water demand.

What does a new water heater installation typically cost? Installed costs for a standard 40–50 gallon tank water heater run $900 to $1,500 on average, depending on your region, the unit itself, and whether any code upgrades (expansion tank, updated venting) are required. Tankless units typically run $1,500 to $3,500 installed. Getting two or three quotes is always worth the effort for a job this size.

Taking 20 minutes to actually diagnose the problem before calling a plumber is almost always worth it. You'll go into that conversation knowing what you're dealing with, what's a fair repair cost, and whether replacement makes more sense. Sometimes the answer is a $15 part and an afternoon fix. Sometimes it's a new unit. Either way, you'll make a better decision with the full picture in front of you.