How To Tell If A Hot Water Heater Is Full (Quickly & Easily!)

Matthew Mountain
by Matthew Mountain

Water heaters can be found in virtually all homes and businesses these days, and this is mainly because humans need access to hot water many times throughout a single day. Knowing the ins and outs of how water heaters work is very beneficial, as you’ll never be without hot water and your system will last a long time.

Knowing at all times how much water is in your tank, for example, is quite important, as a certain level of water is required for a system to run well. In this article, how to determine if a water tank is full or not will be the subject in focus, and you can use the points here to run your system right for as long as you have it.

If you turn on a hot water tap and no air comes out, this is an indication that the hot water heater is full. Some systems also provide visual aids so users know the current water level. No matter how one determines the water level of their heater, doing so often will improve a system’s life span.

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Knowing How Much Water Is in Your Water Heater Is Important

Knowing how much water is in your water heater is important for a few reasons. You should check how much water is present in your heater at least once every month, and more frequently during the months when the system is used often.

Stale Water Can Be Bad Water

Water that has been sitting in a tank for a long time can be damaging, mainly because stale water is almost always rife with minerals and other particles that can break down a water heater.

Some common minerals are sulfur and iron, while scale and other deposits can build up as well. These buildups often occur in the inner walls of heaters and on the pipes as well. If your system is overwhelmed with minerals and deposits, not only will the quality of your water be reduced, but your system may not run effectively either.

For this reason, it’s good to know how much water is in your system at all times. If a certain amount has been sitting there for a long time, you’ll know that it’s time to drain the system so new water can take its place.

There May Be Too Much Demand

Knowing how much water is in a water heater is also important because most water heaters require a certain level of water to operate properly. And if you have a large family that needs hot water often, you’ll want to know that your system has enough water to meet the demand.

Draining and Refilling a Water Heater

Unless you have a water heater which simply shows how much water is in the tank, it’s best to empty and then refill your system when you want to be sure it’s full of good water. A water refresh will also ensure that the new water is not rife with minerals like stale water often is.

To fully drain and then refill a water heater, read through the steps below. Keep safety in mind while you’re working through these steps.

  • Turning off the water heater’s power supply is step one. Find the circuit breaker that’s linked to your heater and switch it to OFF.
  • Next, shut off the cold water valve, which in all likelihood is located near the top of the water heater.
  • Now you must activate any hot water tap in your home, as doing so will let air come into the water tank.
  • If you don’t have a flood drain under your water heater, connecting a garden hose to the system’s drain valve is the next best option; a drain valve is usually located near the bottom of a system. The other end of the hose should lead to a floor drain, sink, shower, or outside.
  • Next—and this part is important—you’ll want to slowly turn the drain valve; doing things slowly will help you avoid scalding. Let the tank empty itself completely.
  • Once the system is empty, the cold water supply valve should be turned on, and the water should be kept running at full pressure for at least a few minutes. At this point, you’ll want to make sure that your system is free of all sediment and minerals.
  • The drain valve can be turned off once the water is completely clear.
  • Next, you should allow your water heater to fill up. You’ll know it’s full when the hot water tap runs normally without any air coming out.
  • Turn off the tap and then put the water heater’s power back on. Your system will be flushed, filled, and ready to go.

How Often Should a Water Heater Be Drained and Refilled?

As was said earlier, flushing out a water heater is important for a variety of reasons. But how often should a water heater be flushed out and refilled?

While the answer to this question really depends on the type of system being used, a good rule of thumb is flushing out a system every one to three years. Another determining factor is the quality of the water the system holds.

Keep in mind that over-flushing a system can damage it. When strongly encrusted sediment loosens, a water heater will become weaker because of corrosion. In the worst-case scenario, rust may cause an untimely end for your system.

When using a propane or natural gas water heater, you should consider flushing out your system at least once a year. Flushing out these kinds of water heaters is more complex than flushing out an electric heater, so you shouldn’t do this on your own.

Get help from a qualified and experienced plumber when you need to flush and refill your water heater. A pro will have the tools, know-how, and experience to get this job done.

When It’s Time to Replace an Old Water Heater

If you begin to notice rust in your water supply, such could be a sign that your heater is about to go. Here’s what else can be done when you think rust is coming from your water heater.

Why Is There Rust in the Water?

Steel may be one of the strongest materials on earth, but even it can be brought down by the long, degenerative process of rusting. If your water heater, and the pipes connected to it, are made of steel, than rusting may indicate that a larger problem is on the horizon.

But often it’s hard to tell where rust is coming from. Is it coming from the pipes or is it coming from the water heater itself? In any case, when you identify rust in your water, you need to address this immediately, as nobody should be consuming, cooking with, or bathing with rusty water.

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Rust Coming From a Water Heater

Water heaters are often blamed when rust is identified in water. If your heater is past its expiration date, rusting is inevitable. Rusting may also occur when a heater is only eight years old.

Rusty Inlet or Pressure Relief Valve

If there is rust around the inlet or the pressure relief valve, it’s likely that rust is also inside the tank. Replacing the tank as soon as possible is, unfortunately, the only option here. Once rust has overwhelmed a system, there’s no saving it.

Rusty Pipes

If the water is coming out rusty, the pipes may be the culprits. Does your piping system utilize galvanized pipes? If so, rust could be the problem here. Sometimes, rusting will be so intense, it’s unmistakable when it manifests in a water supply.

To know whether or not the pipes are the problem, grab a few buckets. Fill each one with hot water from the water heater. If the rust has not dissipated by the third bucket, it’s safe to say the water heater is the problem—not the pipes.

Matthew Mountain
Matthew Mountain

Matt loves everything DIY. He has been learning and practicing different trades since he was a kid, and he's often the first one called when a friend or family member needs a helping hand at home. Matt loves to work with wood and stone, and landscaping is by far his most favorite pastime.

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