Water heater draining

I have read that one should drain the water heater to rid it if any build up. Is this true and how do you do that?

you can read the manufactures instructions, usually printed right on the heater, it will explain the procedure...

You can drain the tank by opening the valve at bottom of the w/h.
You may have problem when you turn itback off as debris may collect
in the valve and make it difficult to stop leaking.If the w/h is 10 yra or
older consider a replacment.

Thanks for the advice. Do I have to turn off the water heater and water source 1st or do I just drain it at the bottom faucet?

Leave the water on otherwise, you'll only get gravity rather than water pressure to help flush out crud. Pluse, if you didn't open a valve somewhere else in the house, you'd have the equivalent of a big straw that you've got your finger over the end. Remember, the water will be hot. Some hoses can't handle heat, plus the metal part of the nozzle could get too hot to hold, so run it where it won't hurt anything. As noted, if you do end up flushing out a bunch of calcium deposits, it can make it hard to get the drain valve to seal if some of it gets caught under the washer. this is something that you probably should do on a regular basis (depending on the water hardness), maybe every 6-months to a year. If it hasn't been done, and it is old, you might not get anything out since it could have solidified into a big hunk. You can often tell when that happens, since the tank will make sort of a burping sound as the deposit creates hot spots and little steam explosions when the burner or elements are on.

On a new tank, it's not a bad idea to have the (usually very) cheap valve replaced with a ball valve that you can be sure it will seal again.

Is it possible to buy rebuild kits for those valves so they will seal again (once you verify that it doesn't seal because you just flushed it)?

I've got an AO Smith heater that is about 15yrs old. Thing works great and I have it set almost as low as it will go. That would tell me there's not a lot of buildup/minerals soaking up the heat right?

I thought about flushing it but don't want to get myself in a jam with a leaky h.w. heater.

You can buy replacement valves for water heaters. All they are is a 3/4" hose bib.

Old, plastic drain valves do have a tendency to snap off, however. If that happens, you need to use a nipple extractor to get it out.

Now that you say "it may make noises", it does. After you use a lot of hot water and the tank refills, you can hear a knocking noise. Is this bad?

It means that there are deposits in the tank. At that age, it could last one-month, or another 5-years. Most tanks don't last that long...

Thanks to all for the great advice.