How to Drain a Water Heater

Why and how to drain a water heater? Draining a water heater is recommended by every manufacturer and plumber; for better performance, to keep desired output constant, for longer heater life and for safer operation.

This article will cover the topic about gas heaters, tank type, as the process of draining is slightly different from the electric models. Use the article about electric heater maintenance to learn how to drain a water heater powered by electricity.

Why to drain the water heater

draining water heater due to the sediments

As with electric heaters, the number one reason why to drain a water heater and flush the system is due to the sediment build-up and dirt collected at the bottom of the tank of the heater (see picture). This is happening because of the imperfect conditions (hard water and mineral content) so regular maintenance should be applied.

The recommendation is to drain and flush the tank every 6 months or annually once, as the part of the standard maintenance.

Probably, the biggest problem that might occur is due to the tank leakage and the damage it causes in the area where it is installed or even your home. Leaking is usually the result of loose connections, corrosive action in the tank...

This is why a pipe to an adequate indoor drain (not outside due to freezing) should be provided, and/or drain pan, installed under the heater. The drain must be easily accessible to allow trouble-free operation and service.

Drain pan is used to collect any water from leaks or condensate in the plumbing or heater's tank. The recommendation is to use a metal drain pan with the outside diameter 2" bigger than the tank diameter and to pipe it to an adequate drain.

Another important reason why to drain hot water heater is in a case of the heater inactivity, so if the unit is subjected to freezing temperatures, heater and piping should be fully drained and the drain valve left open.

drain valve

Draining is sometimes necessary when repairing and replacing components. In a case when replacing the anode rode, only a few gallons of the heater have to be drained, while for gas valve replacement you have to empty the tank.

emergency plumber

Step by step guide how to drain the water heater

  • Turn off the gas at the gas control valve or manual shut-off valve located close to the heater.

  • Close the cold water inlet valve.

  • Open the closest hot water tap to vent the heating system.

  • Use the garden hose and connect it to the drain valve located at the bottom of the heater.

  • Use the other end of the hose and discharge to an adequate drain so it won't cause any damage or injury.

  • You can also use a bucket for this purpose if the draining through the hose is not applicable.

  • Open the heater drain valve and let all the water drain from the tank. Be careful water might be hot. This is the reason to use the appropriate type of the hose.

  • To refill the tank, close the drain valve and follow the instruction how to start the heater.

... or use the video below.

Tips when draining a water heater

As with the electric heaters, one of the ways to prevent lime and sediment buildup is to install a water softener or apply delimer solution. This is an additional cost for your budget, so draining a water heater regularly is the cheapest and simplest solution.

The pressure release valve needs to be open, so air will get into the tank, and water can drain out smoothly. The other way is to open a faucet.

To prevent the risk of burns due to the scalding temperatures, open a hot water tap to allow sufficient cold water to enter the tank.

Don't be surprised if you see dirty water, it is normal. This is because of all the minerals and sediments that had built up.

Flush the rest of sediments out by turning on the water to the tank, and when the drained water is clear, you are done. Use a bucket for this purpose.

When you drain a water heater, the discharge line must pitch downward from the valve so it can drain completely by gravity. When you fill the heater keep the drain valve closed. The time needed to drain water heater depends on the tank size but as you can see it is very simple and the procedure can last one or more hours.