If you’ve ever wondered why your hot water doesn’t last, why your utility bills are rising, or why your water heater makes weird noises, this post is for you. We’re breaking down what sediment is, why it builds up, how it affects your water heater, and what you can do to stop it from turning into a much bigger problem.

What Is Sediment, and Where Does It Come From?

Water heater sediment buildup is the result of minerals—primarily calcium and magnesium—separating from the water and settling at the bottom of your tank. This process happens slowly over time as your water heater operates.

Every time your tank refills, it brings in fresh water. If you live in an area with hard water (which most of Utah does), that water contains a high level of dissolved minerals. When the water heats up, the minerals separate from the liquid and sink. This creates a thick layer of sediment on the bottom of the tank that hardens over time.

In addition to minerals, sediment can also include:

• Sand or grit from the municipal supply
  
• Rust flakes from aging pipes
  
• Corrosion particles from the tank itself

These all contribute to a growing layer of sludge that insulates the burner or heating element from the water it’s trying to heat.

Why Water Heater Sediment Buildup Is a Big Deal

You might assume sediment buildup is just a minor nuisance, but it creates a long list of problems for your water heater, plumbing system, and utility bills.

Reduced Heating Efficiency

When sediment covers the heating element or burner, your water heater has to work harder to do its job. Heat transfer becomes less efficient, meaning it takes longer to heat the water, and more energy gets wasted in the process. That inefficiency translates directly into higher gas or electricity bills.

Overheating and Internal Damage

Sediment acts like an insulating barrier, trapping heat underneath it. This can cause the bottom of your tank to overheat, damaging the metal and the tank’s internal lining. The result? More wear and tear, more frequent breakdowns, and a much shorter lifespan for your system.

This trapped heat can also cause water to boil under the sediment layer, creating pressure bubbles that lead to the popping, banging, or rumbling noises you might hear coming from the tank.

Loss of Hot Water Capacity

The more sediment in your tank, the less space there is for actual hot water. A standard 50-gallon tank with several gallons of sediment might only provide 35–40 gallons of usable hot water. That’s a major issue if you have a large household or rely on long showers, multiple appliances, or back-to-back usage.

Higher Risk of Corrosion

The sediment layer can trap moisture against the tank walls, accelerating rust and corrosion. Once corrosion starts, it’s usually only a matter of time before the tank begins to leak—or fails completely.

Clogged Valves and Pipe Damage

As sediment breaks loose, it can move into the hot water lines, clogging fixtures or damaging valves. Sediment particles can also wear down internal seals and components over time, leading to more frequent plumbing repairs.

Dangerous Pressure Levels

In severe cases, sediment can restrict the tank’s ability to regulate temperature and pressure. If the temperature and pressure relief valve (T&P valve) malfunctions due to sediment buildup, you could be looking at a dangerous pressure spike—or worse.

How to Tell If Your Water Heater Has Sediment Buildup

Most homeowners don’t realize there’s a problem until the symptoms become hard to ignore. Here are the biggest red flags that water heater sediment buildup is happening in your system:

• Rumbling, popping, or knocking noises coming from the tank
  
• Water takes longer than usual to heat
  
• Shorter hot water supply during showers or laundry
  
• Fluctuating water temperatures
  
• Cloudy, dirty, or discolored hot water
  
• Increased gas or electric bills
  
• Water leaking from the bottom of the tank
  
• T&P valve releasing water more often than normal

Even if you’re not seeing these signs yet, it’s worth checking if your water heater hasn’t been flushed in over a year.

How to Flush a Water Heater

Flushing your water heater is the best way to remove sediment buildup before it causes permanent damage. You can do it yourself if you’re comfortable, or hire a pro to make sure it’s done safely and correctly.

Here’s a step-by-step breakdown of the process:

Step 1: Turn Off the Power or Gas

If you have an electric water heater, shut off power at the breaker. For gas units, turn the thermostat to “pilot” or the gas valve to the “off” position.

Step 2: Turn Off the Cold Water Supply

Find the cold water shutoff valve at the top of your tank and turn it off to prevent more water from entering the system.

Step 3: Connect a Hose and Drain the Tank

Attach a garden hose to the drain valve at the base of the tank. Run the hose to a floor drain, bathtub, or outside area where hot water can safely discharge. Open the drain valve and allow the tank to empty.

Tip: Open a hot water tap in your house to help air flow into the tank and speed up the draining process.

Step 4: Flush With Cold Water

Once the tank is empty, turn the cold water supply back on briefly with the drain valve still open. This will stir up remaining sediment and help push it out. Repeat this process until the water runs clear.

Step 5: Refill the Tank and Restore Power

Close the drain valve, disconnect the hose, and turn the cold water supply back on fully. Once the tank is filled, turn the power or gas back on and wait for the water to heat.

Note: If water comes out of the hose looking like sludge or you see large chunks of sediment, you may need a more aggressive flush—or a professional cleaning.

How Often Should You Flush a Water Heater?

How often you flush depends on your local water hardness and usage levels. In most Utah homes, once a year is the minimum.

If your home has very hard water (and most of Utah County does), flushing every six months is a smarter move—especially if your family uses a lot of hot water.

Tankless water heaters also need descaling at least once a year to prevent mineral buildup inside the heat exchanger.

How to Prevent Sediment Buildup for Good

Flushing works, but prevention is better. Here are a few things you can do to reduce water heater sediment buildup long-term.

Install a Water Softener

A water softener removes calcium and magnesium from your water before it reaches your heater. This not only prevents sediment, it also helps protect your plumbing fixtures, pipes, and appliances.

We install softeners all the time across Lehi, Park City, Midway, and the surrounding areas—especially in homes where scale buildup has already started to damage water heaters.

Use a Whole-Home Sediment Filter

If your water contains dirt, sand, or rust from old city pipes, a sediment filter at the point of entry can catch the debris before it enters your system.

This protects your water heater, fixtures, and faucets all at once.

Schedule Annual Maintenance

Annual water heater maintenance helps catch problems early and keeps your system running efficiently. It’s also a good opportunity to inspect the anode rod, which helps protect the tank from corrosion.

What We Do to Help

At Slate Plumbing, Heating and Air, we deal with water heater sediment buildup every day. Whether you need a standard tank flush, a tankless system descaling, or a full water heater replacement, we’ve got the tools and experience to handle it.

We also install water softeners, perform whole-home repipes, and offer solutions to keep hard water from wrecking your plumbing system in the first place.

Don’t wait until your water heater fails or your basement floods. If your system hasn’t been flushed in over a year, or if you’re hearing strange noises from the tank, give us a call.

Final Takeaway

Water heater sediment buildup is one of the most preventable causes of early failure, inefficiency, and expensive plumbing repairs. It’s caused by Utah’s hard water, but with the right maintenance and prevention tools, you can keep your system running strong for years.

Flush your water heater regularly. Install a softener if you don’t have one. And don’t ignore the warning signs—because by the time the tank starts leaking, it’s already too late.

If you want help with flushing, inspections, or upgrading to a softener or new water heater, we’re ready when you are.