1. Find the build date first.
The build date is hidden in the serial number on the label. On common brands, it’s usually on the side of the tank, near the rating plate.
| Brand | How to read the serial number | Example |
|---|---|---|
| Rheem | The first four numbers after the letters are the month and year. | 0619 means June 2019. |
| A. O. Smith | The first four numbers are the year and the week. | 1932 means 2019, week 32. |
| Bradford White | The first two letters are a year and month code that repeats every 20 years. | Text a photo of the label to (208) 555-0163 and we’ll read it for you. |
2. Look at what failed.
Under 8 years, failed part
A pilot or igniter, thermocouple, gas valve, heating element, thermostat or relief valve can often be repaired. Most part repairs are $165 to $395.
Water from the tank
Water coming from the tank body itself, the bottom or a seam means replacement. A leaking tank cannot be repaired.
Old tank, old symptoms
Over 10 years old, rusty hot water, or rumbling and popping that a flush does not stop points to replacement.
3. Use the one-third rule in the middle.
For everything in between, compare the repair to the replacement. If the repair costs more than about a third of a new heater, replacement is usually the better call. We’ll tell you when a $40 part is all it needs.
A real-world example
When we would repair, and when we would replace.
A 9-year-old 50-gallon gas tank with a bad gas valve, a $385 repair against $2,095 for a new one, is well under a third. We would usually repair it. If that same tank were 11 and rumbling after a flush, we would replace it.
The diagnostic visit is $89.
That diagnostic is credited toward your repair or a new water heater, so the visit becomes part of the solution.
Hard water changes the timeline.
Treasure Valley water is hard, which wears tanks out faster. A conventional tank typically lasts 8 to 12 years here. A yearly flush can help reduce buildup, but it cannot repair a tank that has already failed from the inside out.