TL;DR
Water Heater Maintenance
It depends on the age and condition of the tank. On a water heater under about 6 years old, regular flushing, an anode rod check, and a relief valve test are worth doing and help the tank reach its full lifespan. On an older tank, especially one that has never been flushed, servicing can do more harm than good: removing years of sediment can open pinhole leaks, old plastic drain valves can break or stick open, and stirred-up debris can clog fixtures. Our rule: under 6 years, service it; 6 to 8 years, only if it has been flushed before; 8 to 10 years, inspect first; 10 to 12 years or older, plan for replacement instead of flushing.
Ask ten contractors whether you should have your water heater serviced and most will say yes without a second thought. Our honest answer is different: it depends. Servicing a water heater can add years to a healthy tank. On an older or neglected tank, the same service can be the thing that finishes it off.
Most homeowners never hear the second half of that, because it is awkward to explain why a "maintenance" visit might actually kill a water heater. So here is both sides, the way we explain it to our own customers.
The Short Answer: It Depends on the Age of the Tank
Age and condition decide almost everything. As a working rule:
Under 6 years old: yes, service it. This is when a flush and anode check do the most good.
6 to 8 years old: service it only if it has been flushed regularly before. A first-ever flush at this age carries real risk.
8 to 10 years old: inspect first. Do not flush it blindly.
10 to 12 years or older: plan for replacement, not flushing.
The rest of this article explains why the line falls where it does.
When Servicing Your Water Heater Is a Good Idea
On a younger tank in good condition, routine service addresses three things you cannot see from the outside.
Sediment buildup
Every gallon of water entering the tank carries dissolved minerals. When it heats, those minerals settle to the bottom as scale and grit. On a gas unit, that layer insulates the tank bottom from the burner, so the burner runs longer and the steel above it runs hotter than designed. On an electric unit, sediment buries the lower heating element. Flushing a healthy tank regularly keeps that layer from building up in the first place, which protects efficiency and keeps the tank from overheating at the bottom.
The anode rod
Inside every steel tank is a sacrificial anode rod, usually magnesium or aluminum, that corrodes so the tank walls do not. Once the rod is used up, corrosion moves to the tank itself, and there is no repair for a rusted-through tank. A typical rod lasts 3 to 5 years, less with hard water or a water softener. Checking it every 2 to 3 years and replacing it while the tank is still sound is one of the few things that genuinely extends a water heater's life.
The relief valve
The temperature and pressure relief valve is a safety device that opens if the tank overheats or over-pressurizes. Valves that are never tested can seize from mineral deposits. A quick test on a healthy tank confirms the protection is still there.
Servicing makes the most sense when:
The tank is under 6 years old.
You live in a hard water area, such as Parker, where sediment builds faster.
There is no corrosion at the base of the tank.
The drain valve is in good condition.
You want to get the maximum lifespan out of a newer unit.
When Servicing Can Do More Harm Than Good
This is the side most companies skip. On an older tank, servicing carries real risks.
1. Flushing an older tank can make it fail sooner
When a tank is 8 to 12 years old or more, sediment often acts like a bandage. It seals tiny pinhole leaks, cushions weak spots in the steel, and keeps water away from thin areas of metal. Flush the tank and you remove that patch. A pinhole becomes a leak, a weak spot ruptures, or the tank starts dripping and then fails outright.
That is why many plumbers follow a simple rule: if it is old, do not touch it. It is not laziness. It is risk management.
2. The drain valve can break or get stuck
Most factory drain valves are inexpensive plastic. On an older tank, opening one can cause it to snap off, leak afterward, refuse to close fully, or clog with sediment partway through. When that happens you are looking at a tank that will not stop draining, an emergency shutoff, and often a same-day replacement. It is one of the most common "unexpected" failures after a flush.
3. Stirred-up sediment can clog your plumbing
Years of mineral buildup do not always leave the tank cleanly. Once it is stirred up, it can travel into the house and clog faucet aerators, block shower cartridges, jam mixing valves, and reduce hot water pressure. The flush did not cause the sediment, but it is what moved it, and the result is a shower that barely works.
4. Flushing can expose a failing anode rod or a rusted tank
If the anode rod is already gone and the tank is rusting from the inside, a flush can release rust flakes, turn your hot water brown, and accelerate the deterioration. In many of these cases the tank was already dying. The flush just makes it obvious.
5. The return on an older tank is low
For a tank near the end of its life, a flush will not gain you meaningful efficiency and will not extend its lifespan in any real way. What it might do is trigger a failure, which is often what many companies are hoping for. The risk outweighs the benefit, which is why many companies avoid flushing older tanks entirely.
6. Maintenance cannot undo age
Servicing a tank does not reset its lifespan, fix corrosion, repair a tank whose anode rod has already been used up, prevent rust-through, or make an old tank like new. If you expect a service visit to do any of that, it is easy to feel misled when the tank fails a few months later.
7. "It was fine until you touched it"
If a technician flushes a 10-year-old tank and it fails the next day, it looks like the service caused the failure, even though the tank was already at the end of its life. This is exactly why the age rule above exists, and why a good technician will sometimes recommend against servicing your water heater.
Servicing is usually a bad idea when:
The tank is 6 to 12 years old or more and has not been maintained.
There is visible rust or corrosion.
The plastic drain valve looks brittle.
The tank is rumbling heavily during heating cycles.
You are expecting "like new" results from an old unit.
The tank is already near the end of its life.
If your water heater falls into this group, the more useful question is whether to replace it on your schedule or wait for it to fail. We cover that decision in our guide on replacing a water heater before it dies, and our water heater replacement cost guide lays out what to budget.
What About Tankless Water Heaters?
The age risks above are specific to tank water heaters, because they come from sediment and corrosion inside a steel tank. Tankless units are different. They heat water as it passes through a compact heat exchanger, and scale builds up inside that exchanger quickly, especially with hard water. Periodic descaling is part of normal ownership, and many manufacturers require documented descaling to keep the warranty valid. If you are considering the switch, our tankless water heater installation page covers what it involves.
Signs Your Water Heater Needs Attention Now
Whatever its age, do not wait if you notice any of these:
Moisture at the base of the tank. Tanks rarely burst without seeping first.
Rusty or brown hot water, which often means the anode is gone and the tank is corroding.
Heavy rumbling or popping during a heating cycle.
Hot water running out much sooner than it used to.
A dripping relief valve, which points to excess pressure or a failing valve.
Soot, scorching, or a yellow burner flame on a gas unit. Treat that as urgent.
If you have no hot water at all, start with our no hot water quick checks.
The Bottom Line
Servicing a water heater is good when the tank is healthy. It is bad when the tank is old, corroded, or fragile. A newer tank in good condition benefits from regular flushing and anode checks. An older tank that has never been maintained is usually better left alone and planned for replacement.
If you are not sure which group your water heater is in, have it looked at before anyone opens the drain valve. Our technicians will tell you honestly whether it is worth touching, help with water heater repair when something has failed, and handle water heater installation when it is time for a new one. Contact our team to get a straight answer.
Sources & References
U.S. Department of Energy, Water Heating, Office of Energy Efficiency and Renewable Energy, 2025
U.S. Department of Energy, Water Heater Maintenance and New Water Heater Selection, Energy Saver Program, 2025
ENERGY STAR, Water Heater Product Criteria and Maintenance Guidance, U.S. EPA and U.S. Department of Energy, 2025
U.S. Consumer Product Safety Commission, Tap Water Scalds, CPSC Document 5098
International Association of Plumbing and Mechanical Officials, Uniform Plumbing Code: Water Heater Relief Valves and Thermal Expansion, 2024 Edition
Not sure if your water heater is worth servicing? MoJo Home Services gives Denver Metro homeowners a straight answer on water heater repair and replacement. Contact us at 4000 Newman St, Wheat Ridge, CO 80033 or call (720) 807-4050 to have yours looked at.
Frequently Asked Questions
Should I flush my water heater every year?
If the tank is under about 6 years old and in good condition, yes. A yearly flush keeps sediment from building up, and in hard water areas it may be worth doing more often. If the tank is older and has never been flushed, do not start now without an inspection. Years of sediment can be holding a weak tank together, and removing it can open leaks that were not there before.
Is it safe to flush an old water heater?
Often it is not. On a tank 8 to 12 years old or more, sediment can seal pinhole leaks and cushion thin spots in the steel, and the factory plastic drain valve may be brittle. Flushing can turn a quiet tank into a leaking one, or leave you with a drain valve that will not close. For older tanks, an inspection is the safer first step, and replacement planning is usually a better use of money than a flush.
Why is my hot water brown after a flush?
Brown or rusty water after a flush usually means the anode rod is used up and the inside of the tank is corroding. The flush released rust that was already there. A short burst of discolored water that clears quickly can be loose sediment, but water that stays rusty is a sign the tank is near the end of its life and should be evaluated for replacement.
My water heater is 9 years old and has never been serviced. What should I do?
Have it inspected rather than flushed. A technician can look for corrosion at the base, check the drain valve and relief valve, and listen for heavy rumbling that signals a thick sediment layer. If the tank shows its age, the practical move is to plan a replacement on your own schedule instead of risking a failure in the middle of a cold week.
Can I flush the water heater myself?
On a newer tank that has been flushed before, a partial flush is within reach for most homeowners: turn off the power or set a gas unit to pilot, connect a hose to the drain valve, and draw off water until it runs clear. The water is scalding, so handle the hose carefully. On an older tank, or one that has never been flushed, leave it alone. Opening an old plastic drain valve is one of the most common ways a working water heater turns into an emergency.
Does a tankless water heater need service?
Yes. The age risks that apply to tanks do not apply the same way to tankless units, but scale builds up inside the heat exchanger, especially with hard water. Periodic descaling keeps the unit running properly, and many manufacturers require documented descaling to keep the warranty valid.
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