How to Flush a Water Heater

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Sediment from the bottom of a hot water heater can clog the low-quality drain valves that come with most water heaters. Replacement with a brass ball valve is the best option.

By the DIY experts of The Family Handyman Magazine

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Sediment from the bottom of a hot water heater can clog the low-quality drain valves that come with most water heaters. Replacement with a brass ball valve is the best option.

Remove the old valve

Article

Remove the old valve

1 of 3

Photo 1: Remove the valve

Remove the old valve. If it breaks off, saw the broken portion with a hacksaw blade until you hit metal threads. Then use a hammer and screwdriver to chip out the pieces.

2 of 3

Photo 2: Assemble the new valve

Remove the handle from the ball valve so you can assemble all the 3/4-in. fittings.

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Photo 3: Flush

Install the new ball valve and flush the sediment into a bucket. Let the water flow until it runs clear.

« Previous Photo Next Photo »

Draining sediment several times a year is an effective way to reduce energy costs and increase the life of your water heater. Unfortunately, most water heaters come with crummy valves. And once you open them to drain the sediment, the debris clogs the valve, keeping it from sealing. But you can replace the crummy factory drain valve with a full-port ball valve. The actual valve replacement takes about an hour, but sediment buildup may slow the draining process. So set aside a full morning for this project.

Start by shutting off the water heater's power or gas supply. Open any hot water faucet until you run out of hot water. Leave the faucet on, close the cold water valve to the tank, and then hook up a garden hose to the valve to drain the tank. After the tank drains completely, unscrew and remove the valve by turning the plastic nut behind the knob. If the valve breaks, don't panic (see Photo 1). Stick a wire coat hanger through the opening to break up the sediment. Assemble the new valve (Photo 2), shut off the faucet and reopen the cold water supply valve to flush out the tank (Photo 3).

Caution!

Remove the ball valve handle after you flush the water heater, especially if the water heater is located where people could walk by it and accidentally bump the handle. The valve could open and release scalding water, causing serious burns. (Twist-tie the handle to the valve so you don't lose it.)

Tools & Materials

Required Tools for this Project

Have the necessary tools for this DIY project lined up before you start—you’ll save time and frustration.

Hammer
4-in-1 screwdriver
Adjustable wrench
Bucket
Hacksaw
Knee pads
Plumbers tape
Rags
Slip joint pliers

You'll also need a garden hose.

Required Materials for this Project

Avoid last-minute shopping trips by having all your materials ready ahead of time. Here's a list.

Dielectric nipple
Brass elbow
2" brass nipple
Brass ball valve
Garden hose adapter

Shopping List

How to Flush a Water Heater - Shopping List

Comments

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AAB

May 07, 1:42 PM [GMT -5]

One thing to always check on your hot water heater is if the pipes are connected correctly. I have fixed over 3000 water heaters in a twenty-five year period and at least two or three times a year, I find a water heater that was installed backwards.
The cold water should come in on the right, as you face the controls. If connected backwards, the cold water will come in at the top (left side) and the hot water will have to be pushed through the sediment and up the dip tube.
Most often, the customer complains of restricted water flow on the hot water side.

If you flush a water twice a year it works great, most people never bother until they have a problem, in which case, a shop vac is the only way to clean out a water heater.

pete1

September 08, 7:39 PM [GMT -5]

I have had my electric hot water heater for 19 years. Every six months I change the upper and lower rods because of the large amount of calcium in our water. The rods cost around $20 for the both but pay for themselves with-in a few months. I used to vacuum the bottom out by connecting a flexible clear hose to my wet vac and it worked well for many years. Then I found a pvc angled tube made especially to vacuum out the calcium at a local hardware store (not the big guys). I works fantastic and takes less time. Flushing the system never gets all the sediment out and that left over material is what causes the rust to start and then goes your tank. I do like the idea of adding vinegar for those little areas. For energy efficient I always hear of flushing the system but never changing the rods. The rods do build up with calcium causing them to work harder and longer (more energy usage). I do see the big difference in my electric bill every time I change them.

Toid

November 20, 5:27 PM [GMT -5]

If you dump a couple gallons of white vinegar into the inlet or outlet of the tank and let it soak in the bottom of the tank of a while it will eat most of the calcium up, or atleast make it easy to flush out with water.

shacko

October 06, 1:52 PM [GMT -5]

lefty18jcsOctober 06, 2010

Has anyone tried to loosen the sediment by shooting compressed air through the drain valve? Can this be done without too much danger?

I don't think that is a good idea. You take the chance of forcing some of the sediment into the pipes and causing another problem.

If you FLUSH your tank on a yearly basis (like most manufactors recommend) you shouldn't have a lot of sediment in there.

shacko

October 06, 1:40 PM [GMT -5]

One comment only. Instead of taking the handle off you can get a hose thread cap. some types of ball valves the handle is used to seal the bushing in the top; take it off and they will leak

lefty18jcs

October 06, 1:26 PM [GMT -5]

Has anyone tried to loosen the sediment by shooting compressed air through the drain valve? Can this be done without too much danger?

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