TL;DR
Water Heater Maintenance
Yes, and the reason is straightforward economics. A tank water heater left unserviced typically lasts 8 to 12 years, while one that gets an annual flush and periodic anode rod replacement often reaches 15 years or more. Service addresses three things a homeowner cannot see: sediment insulating the bottom of the tank, a sacrificial anode rod that corrodes away and then leaves the tank steel unprotected, and a temperature and pressure relief valve that is a genuine safety device. Tankless units need service even more, since scale inside the heat exchanger reduces output and voids many warranties when descaling is skipped.
Water heaters are the appliance nobody thinks about until there is cold water in the shower or a puddle spreading across the floor. They sit in a basement or a closet doing their job quietly for a decade, which makes them very easy to ignore and very expensive to ignore for too long.
So is annual service actually worth it, or is it a line item contractors like to sell? The honest answer is that water heater service is one of the better returns in home maintenance, but only if you understand what a real service visit covers. A quick look and a handshake is not service. Knowing the difference is what makes the money worth spending.
What a Real Service Visit Actually Covers
A legitimate water heater service is a defined set of tasks, not a general inspection. On a conventional tank unit, it should include:
Draining and flushing the tank to remove accumulated sediment from the bottom.
Inspecting the anode rod and replacing it when it is substantially consumed.
Testing the temperature and pressure relief valve to confirm it operates and reseats.
Verifying the thermostat setting and measuring actual delivered water temperature.
Checking the expansion tank pressure where one is installed.
Inspecting combustion and venting on gas units, including draft, burner condition, and flue integrity.
Examining connections, the drain valve, and the base of the tank for corrosion or early seepage.
If a service visit does not include the flush and an anode inspection, the two items that most directly determine tank life, it is not addressing the things that matter.
The Anode Rod Decides How Long Your Tank Lives
This is the part most homeowners have never heard of, and it is the single most important component in a tank water heater's lifespan.
A steel tank holding hot water will corrode. Manufacturers deal with this by suspending a rod of magnesium or aluminum inside the tank. That metal is more chemically reactive than steel, so it corrodes preferentially and protects the tank walls. It is called a sacrificial anode because sacrificing itself is the entire job.
The rod is consumed over time. Once it is gone, corrosion moves to the next available metal, which is the tank itself. From that point the tank is on a countdown, and there is no repair for a rusted through tank. Replacement is the only option.
A typical rod lasts 3 to 5 years, less where water is mineral rich or where a water softener is installed, since softened water accelerates anode consumption noticeably. Inspecting the rod every 2 to 3 years and replacing it when it is heavily eroded or has exposed core wire is what turns an 8 to 12 year appliance into a 15 year one. The replacement rod itself is an inexpensive part. Its value is entirely in the timing.
If your unit is already well past the point where anodes were maintained, the more useful question becomes whether to replace on your schedule or wait for a failure. We covered that decision in our guide on replacing a water heater before it fails.
Sediment Is Not Cosmetic
Every gallon of water entering the tank carries dissolved minerals. When it heats, those minerals precipitate out and settle to the bottom as a layer of scale and grit.
On a gas water heater, the burner sits directly beneath that layer. Sediment insulates the tank bottom from the flame, so the burner runs longer to heat the same water, and the steel above the burner runs hotter than designed. That thermal stress is a known cause of premature tank failure. The rumbling or popping sound an older water heater makes is steam bubbles forming under the sediment layer and forcing their way out.
On an electric unit, sediment buries the lower heating element, which shortens element life and reduces recovery rate.
The consequences show up in ways homeowners usually blame on age:
Hot water running out faster than it used to, because sediment occupies tank volume.
Higher energy use for the same amount of hot water.
A drain valve that clogs solid, which turns a routine flush into a service problem.
Rumbling, popping, or knocking during a heating cycle.
An annual flush prevents all of it. In areas with mineral rich water, twice a year is not excessive.
The Relief Valve Is a Safety Device, Not a Fitting
The temperature and pressure relief valve is designed to open if the tank exceeds roughly 210 degrees Fahrenheit or 150 pounds per square inch. It exists because a sealed vessel full of superheated water stores a genuinely dangerous amount of energy.
Relief valves fail in two ways. They can seize shut from mineral deposits, which removes the protection entirely, or they can fail to reseat after testing and weep continuously. Testing annually is standard practice precisely because a valve that has never been operated is the one most likely to be stuck.
Two related items belong in the same inspection. The discharge pipe must run downward and terminate near the floor, so that if the valve opens, scalding water is directed safely rather than sprayed. And on a closed plumbing system, meaning one with a backflow preventer or pressure reducing valve at the service entrance, a thermal expansion tank is required. Without it, water expanding as it heats has nowhere to go, system pressure spikes on every cycle, and both the relief valve and the tank take the abuse.
What Service Costs Versus What It Prevents
Here is the arithmetic that answers the question in the title.
An annual service visit is a modest, predictable cost. Replacing a tank water heater is a project running into the low thousands once you include the unit, labor, permit, disposal, and any code updates triggered at replacement, such as adding an expansion tank or correcting venting. Our breakdown of water heater replacement costs lays out the components.
If routine service extends a tank's life from 10 years to 15, it has deferred that entire replacement cost by half a decade. Even one avoided failure changes the math decisively, and that is before counting the water damage a burst tank causes in a finished basement, which is frequently the largest cost of all and the one insurance conversations revolve around.
There is an efficiency argument as well. Water heating is typically the second largest energy use in a home after space conditioning. A tank fighting through a sediment layer burns more fuel for the same result, every day, for years.
Warranty terms matter too. Many manufacturers require documented maintenance for warranty coverage to remain valid. A tank that fails in year seven of a ten year warranty may not be covered if no service history exists.
Tankless Units Need Service More, Not Less
A common misconception is that going tankless eliminates maintenance. The opposite is closer to true.
Tankless units heat water on demand by passing it through a compact heat exchanger at high temperature. That is precisely the condition under which minerals deposit fastest. Scale inside the exchanger restricts flow, reduces heat transfer, triggers error codes, and eventually damages the unit. The fix is periodic descaling, in which a pump circulates a descaling solution through the exchanger for 45 to 60 minutes.
Most manufacturers specify descaling every 12 months, and more frequently where water is mineral rich. Many also make documented descaling a condition of the warranty, which is a long warranty on an expensive appliance and worth protecting. A full tankless service also includes cleaning the inlet screen filter, inspecting the venting, and verifying gas pressure and combustion. If you are weighing a tankless upgrade, our tankless water heater installation page covers what the switch involves.
What You Can Do Yourself, and What You Should Not
Some of this is reasonable homeowner work.
Reasonable to do yourself: checking the thermostat setting, keeping the area around the unit clear, looking for moisture at the base, and performing a partial flush by attaching a hose to the drain valve and drawing off a few gallons. Setting the thermostat to about 120 degrees Fahrenheit is worth doing: it reduces scald risk, slows mineral deposition, and lowers standby losses.
Better left to a professional: anode rod replacement, which often requires substantial torque to break loose and clearance above the tank; relief valve testing and replacement; any work involving gas connections, combustion, or venting; expansion tank service; and tankless descaling on a unit still under warranty. Combustion and venting in particular carry carbon monoxide risk, which is not a category for experimentation.
Water heater service also pairs naturally with seasonal heating and cooling maintenance, since the same visit can cover multiple systems. Our seasonal maintenance checklist shows how the tasks line up through the year.
Signs Your Water Heater Needs Attention Now
Do not wait for the next scheduled visit if you notice any of these:
Rusty or discolored hot water, which often means the anode is gone and the tank is corroding.
Any moisture at the base of the tank. Tanks rarely burst without seeping first.
Rumbling or popping during a heating cycle, indicating heavy sediment.
Hot water running out much sooner than it used to.
Water that smells of sulfur, a bacterial interaction often tied to anode condition.
A relief valve that drips, which points to excess pressure or a failing valve.
Any soot, scorching, or a yellow burner flame on a gas unit, which is a combustion problem and should be treated as urgent.
When you do schedule work, it is worth knowing what separates a thorough contractor from a fast one. Our guide on questions to ask before hiring a home services company applies directly here.
The Verdict
Yes, having your water heater serviced is a good idea, and the case is not a close one. An annual visit costs a small fraction of a replacement, extends usable life by years, protects warranty coverage, keeps energy use where it should be, and catches safety issues on gas equipment that no homeowner is positioned to spot.
The caveat is that the service must be real: a genuine flush, an anode inspection, a relief valve test, and a combustion check. Ask what is included before booking, and ask what was found afterward.
Our licensed technicians perform complete water heater maintenance on tank and tankless systems, and handle water heater repair when service uncovers a problem. To get on a maintenance schedule or have an aging unit evaluated, contact our team.
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
Ready to schedule water heater service? MoJo Home Services provides professional water heater maintenance, repair, and installation throughout the Denver Metro Area. Contact us at 4000 Newman St, Wheat Ridge, CO 80033 or call (720) 807-4050 to book a visit.
Frequently Asked Questions
How often should a water heater be serviced?
Once a year is the standard interval for both tank and tankless units. Where water carries a heavy mineral load, a tank flush twice a year is reasonable and tankless descaling may be needed more often than annually. The anode rod runs on a longer cycle: inspect it every 2 to 3 years and replace it when it is substantially eroded or the core wire is exposed. If your home has a water softener, shorten that inspection interval, because softened water consumes anodes considerably faster than untreated water does.
Can I flush the water heater myself?
A partial flush is within reach for most homeowners. Shut off the power or set a gas unit to pilot, connect a hose to the drain valve, run it to a floor drain or outside, and draw off several gallons until the water runs clear. Two cautions. The water is scalding, so treat the hose and the discharge accordingly. And older drain valves, especially plastic ones, can clog with sediment or fail to reseat after being opened, which turns a maintenance task into a leak. If the unit has never been flushed and is more than a few years old, having the first one done professionally is the safer choice.
What temperature should my water heater be set to?
About 120 degrees Fahrenheit is the widely recommended setting. It is hot enough for normal household use, low enough to substantially reduce scald risk, and it slows both mineral deposition and standby heat loss. Higher settings around 140 degrees are sometimes used where there is concern about bacterial growth in a large or infrequently used system, but that increases scald risk and generally calls for a thermostatic mixing valve at the outlet to temper the delivered water. If you have young children or older adults in the home, 120 degrees is the sensible default.
Does hard water shorten a water heater's life?
Significantly. Higher mineral content means more sediment accumulating in a tank and faster scale formation inside a tankless heat exchanger. Tanks in mineral rich water often need flushing twice a year rather than once, and tankless units may need descaling more frequently than the manufacturer's baseline interval. A water softener helps with scale but introduces its own consideration: softened water is more aggressive toward the anode rod, so the rod is consumed faster and needs inspection on a shorter cycle. Neither situation is a problem if maintenance intervals are adjusted to match.
Is a small leak at the base something I can wait on?
No. Moisture at the base of a tank rarely resolves and is often the first visible sign that the tank itself has corroded through. There is no repair for a failed tank, and the gap between a seep and a full failure can be short. Before assuming the worst, rule out the simpler sources: a dripping relief valve, condensation on a cold inlet line, a loose drain valve, or a fitting at the top of the tank. If those are ruled out and water is coming from the tank body, plan a replacement now rather than after the tank empties itself onto the floor.
Does maintenance keep my manufacturer warranty valid?
Often, yes. Many manufacturers condition warranty coverage on the unit being installed to code and maintained according to their instructions, which typically means periodic flushing, anode inspection, and for tankless units documented descaling. When a tank fails inside the warranty period, the manufacturer may ask for evidence of that maintenance. Keeping service records, including dates and what was performed, costs nothing and can be the difference between a covered replacement and paying out of pocket. Ask your technician to leave written documentation after each visit.
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