Over time, sediment can build up in your hot water heater. If enough sediment builds up, it blocks heat and can also effectively decrease the size of your tank. You need to turn up your heater to maintain sufficient hot water to fill a bathtub or give you a shower, which can increase the risk of scalding. (For the same reasons, you should not buy an undersized water tank and crank it up.)
Chances are you don’t have a huge buildup, but to keep your heater working as it was intended, you should drain the sediment on a regular basis — maybe four times a year. Here’s how.
Get a length of garden hose which will reach from the tank to a floor drain or sump basin. Attach this to the drain valve on the tank.
Turn down the heat or shut off the heat supply, and run some hot water at another location for a few minutes to cool down the water in the tank. Turn off the water
Open the valve and drain a few gallons from the tank. Watch what’s coming out of the hose to get an idea of the amount of solids. If you haven’t done this in awhile, you could have a bunch of gunk. Turn on another faucet again, and flush out the heater for a few minutes.
If you have enough sediment, you may find the outlet plugged. Shut off the supply to the tank, and with a faucet on to relieve pressure, try and unplug it with a plumbers snake or straightened coathanger. Beware of the hot water.
Once you start draining your tank regularly, you shouldn’t get a huge buildup, and you should simply need to drain a few gallons each time.