Hot Water Heater Calcium Removal [How to Guide]

Nothing is more annoying than trying to take a shower and your water spraying in different directions. You probably also notice a hazy water appearance and nasty particle discharge. Or worse, it reeks of an earthy or rusty smell. This is usually due to the sediment settled inside the tank, which means you need to figure out how to remove calcium from your hot water heater.

remove calcium from hot water heater

Knowing how to get rid of calcium deposits from your hot water heater is a basic skill. Calcium deposit is a prevalent problem among water heaters, but it is something that you can solve easily. All you need is a cleaning solution, and a little elbow grease to get started. Regular descaling of the unit will extend its lifespan and prevent it from rapid depreciation. This post will give some insight into descaling the tank as a preventive measure against damages.

Hard Water and Its Effect on Hot Water Tank

Hard waters contain a high amount of dissolved minerals like calcium and magnesium. These sediments build up in the tank especially when the water is left stagnant for quite a while. In some countries, households use a water softener. However, it does not guarantee the complete dissolution of the minerals that the water contains.

These minerals will eventually settle and calcify at the bottom of the tank. Because of it, the tank’s heating elements will struggle to heat up as these minerals insulate them. It decreases the heater’s efficiency and may damage the tank over time.

Thus, plumbers recommend regularly flushing your hot water tank. You can do this once or twice a year to remove sediments and improve the water tank’s performance. Conventional water tanks may need regular flushing compared to tankless hot water heaters. That is because conventional tanks tend to hold more mineral deposits from storing water.

How to Remove Calcium from Hot Water Heater – Conventional Tank Heater

Using the water heater at a high temperature will produce more lime scale buildup. Minerals dissolve when heat is applied. But at a very high temperature, they will build up faster and settle around the heating elements of the tank. So, instead of anticipating costly repair, here are comprehensive steps in flushing out sediments from your tanks water heater.


  • Pump
  • Bucket
  • Hose
  • Biodegradable cleaning solution
  • Socket wrench
  • Funnel
  • Valve


  • Disable the main power source of your tanks water heater and turn off the cold-water supply. For a gas-powered heater, set the knob to “pilot.”
  • Open the hot water faucet in the house to prevent vacuuming.
  • Turn off the hot (red) and cold (blue) isolation valves on the tank.
  • Hook the hose into the drain valve at the bottom of the tank and turn it on. Remember to extend your hose outside where it is safe to discharge hot water. You can also cover the drain cover to prevent accidental scalding in case the hose leaks or bursts.
  • Open the pressure-relief valve at the top of the unit to facilitate proper water flow while still keeping the drain valve open. This will flush out the sediments.

How to Completely Descale the Bottom of the Tank

The first part of this post simply involves flushing out sediments. But if you think flushing does not solve your sediment buildup problem, you may use a more intensive cleaning method. It involves adding a biodegradable cleaning solution to the tank.

However, plumbers warn against using any type of acid cleaning solution on your water heater. The cleaning agent that the professionals use still depends on the type of material that your water tank is made of. They are also the ones knowledgeable on the correct proportion of the mixture.

calcium deposit water heater

But some do-it-yourselfers swear by the effectiveness of distilled vinegar or apple cider vinegar. Its acid content can break up mineral buildup inside the tank. That’s why these natural cleaners are also trusted household cleaning agents.

Here are the steps on how to remove calcium from a hot water heater thoroughly using white vinegar:

  • Close the drain valve. Remove the anode rod at the top of the heater.
  • Place a funnel into the opening and pour the vinegar solution. You will need about 4 gallons.
  • Put the anode rod back and fill the tank with hot water for about five minutes.
  • Let the solution set for 24 hours before draining and flushing.
  • Close the drain valve and open the cold-water valve.
  • Turn on the faucet inside the house until water comes out. When it does, turn it off again and turn on the water heater.

Descaling a Tankless Water Heater

Tankless water heaters are efficient and easier to maintain than conventional tank storage. But even if it does not store hot water, it still requires regular descaling as it is still prone to corrosion. The mineral deposit from hard water can also clog up the water passages. So, it is important to get rid of calcium buildup to keep it at an optimum working level.


  • Submersible pump
  • Washing machine hose
  • Cleaning solution
  • 5-gallon bucket


  • Turn off the tankless water heater and then the gas valve.
  • Close the hot and cold-water supply valve.
  • Open the flush kit that looks like a hose bib underneath the hot and cold isolation valves. Open the isolation valves to drain the water entirely.
  • Remove the pre-filter underneath the unit and clean it out.
  • Insert the washing machine hoses on the flush kit.
  • Connect the hose under the blue valve to the submersible pump.
  • Submerge the pump and the other hose into the cleaning solution and turn the pump on.
  • Run the pump for about an hour to thoroughly clean the unit.


Calcium and other mineral deposits may affect the efficiency and operation of the hot water heater. Regardless of if you are using the conventional or tankless system, you need to know the basics of how to remove calcium deposits from hot water heaters.

You should also treat it with an organic and natural cleaning agent to break down the sediments. It will make it easier to flush the particles out of the system. Descaling the heater at least once a year is important to keep it working for a longer period and at optimum performance.

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