We take water heaters for granted until something goes wrong. Your water heater needs maintenance regularly. If you’re looking for the answer to how often do you need to flush and service the heating unit? Then, we got you!

To keep it protected from mineral deposits, you need to service the water heating unit at least once a year. If your residential unit has a hard water supply, then you should consider flushing at least every six months.

 If the water softener is installed within the tankless heater, you can skip the unit’s service for two years. But maintaining the valve pressure and flushing annually is highly recommended.

This article will provide you with complete information on when, why, and how to flush your water heater. 

Have a look at Quick Chart before scrolling any deeper.

Unit TypeFlushing Time Period
Tankless Heater (Runs on Hard Water)Minimum 6 Months – Maximum 09 Months
Tankless Heater (Heat’s Soft Water)Minimum 6 Months – Maximum 12 Months
Electric Tankless Hot Water HeaterOnce a Year
Gas Water HeaterMinimum 8 Months – Maximum 12 Months

How often does a water heater need to be flushed?

It is strongly advised to service a water heater at least once a year. Due to heat, minerals in water can build up and rot the walls of the heating unit. 

To negate this problem, a tankless water heater requires periodic flushing.

How Often Should You Flush a Tankless Water Heater Depending on Water Type?


Descaling annually is excellent for the overall health of water heating units. 

  • If your area is supplied with hard water, flush out your hot water tankless heater every six months.
  • If your residential bloc has a soft water supply, then sediment flushing will serve the purpose once a year.

Do you need to descale a water heater if you have a water softener?

If you have a water softener installed within the unit, you can skip the descaling for 18 months. But, It is always advised by manufacturers to flush a heater every year.

How to Flush Sediment Out of a Tankless Water Heater?

Due to heat and steam, calcium and other minerals in water can build up and destroy the heating unit. 

Service your tankless water heater once a year following these steps:

  1. Turn off the cold water supply.
  2. Cut the power supply.
  3. In the case of a gas water heater, cut the supply by turning off the valve.
  4. If you have an electric hot tankless water unit, shut off the breaker.
  5. Allow the unit to cool down for 90 minutes.
  6. Turn on the hot water tab nearby. This will help to prevent any vacuum.
  7. Connect the garden hose to the drainage spigot.
  8. Turn on the spigot and let the water run for several minutes.
  9. Reopen the cold water supply and let the tank fill again.
  10. Drain again and repeat this step until you get rid of all the sediment.
  11. Close the drain valve and reopen the supply valve.
  12. Power up the water heater and run a test trial.

It is always advised to be careful while dealing with electric appliances.

Is it essential to flush the tankless water heater annually?

Yes, it is necessary to drain the water heater once a year for better performance. It is recommended to rinse it every six months if your heating unit has a hard water supply.

Why is it essential to service your water heater once a year?

Annual service has a significant impact on heating units. It enhances their work. Apart from that;
It reduces the repairs
Ensure the units better performance
Minimize the scaling effect
Improves the heat speed
No noise
No clogs

How can you make your water heater last longer?

The long life of a water heating unit can be ensured by;
Flushing and draining it at least once annually
Pressure relief valve testing after every six months
Annual maintenance can add up five years to a gas tankless water heater.

What will happen if you stop flushing the water heater unit?

The longer it goes without any annual service, the more minerals it will stick to the bottom of the tank. It will cause problems like;
Less efficiency
Corrosion and clog
Blockage of valve
More energy consumption
It is also advised to service the tankless water heater, even if it’s not being used.

How annual flushing helps the health of your water heater?

Regular service adds up at least five years more to its life. 

Life of a Water Heater: 8 to 12 years
Life of a Tankless Water Heater: 12 to 15 years
Tankless Gas Heater with annual flushing: up to 20 years.

Due to mineral collection in the tank, the heating unit may rot. Such sediments wash out during heater service, which is great for the unit’s overall health.


Flushing the tankless water heater is very crucial. It enhances productivity and longevity. Residential areas with hard water supply need to service their heating unit every six months. If the water quality is “Soft” or “water Softener” is pre-installed, then an annual sediment flushing will add five years to the life of a tankless water heater.


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