Do I really need to flush my hot water heater?

Question

I've seen a few posts on the internet that say that water heaters should be flushed every year and "I bet you never knew you should be doing this!" After searching around most of the articles that explain why this is the case also include that "by the way, our company can provide this service for you" - so I'm a little skeptical of the actual necessity. I found one article that stated that most water from municipal supplies is good enough that it won't cause sediment build-up and doesn't require flushing. I've also seen an article describing how flushing old tanks could actually cause leaks by removing excess build-up that had been keeping them plugged.

So who actually needs to be flushing their hot water heaters regularly? For my own situation we live in a major US city and have a 3yo gas-powered tank heater. I'd expect ours is in good shape currently but want to make sure we're maintaining it properly.

Answer 1

All tank water heaters collect stuff in the bottom of the tank. It's may be sand, dirt, small pebbles, mineral deposits, rust, or whatever. But over time you get a layer of it there.

In electric water heaters this doesn't cause much trouble other than some loss in capacity as the "stuff" displaces water in the bottom. But in gas water heaters it can insulate the bottom of the tank and prevent efficient heating of the water.

When I've had a gas water heater, I flushed it and often got quite a bit of material out.

Is it a "need" thing? Probably not, you may lose some efficiency and some lifetime of the unit but probably nothing drastic.

Would I pay someone to come and flush it? No. It's quick and easy to do yourself.

Answer 2

The obvious first step is: do a flush and examine the product. If it's perfectly clear, then no need to flush (or flush as often).

Now, water heaters with an internal electric heating element or with a heat exchanger (hot water supplied externally as a loop in a forced-hot water system) are more prone to generating metal gunk as the heat exchanger ages. Modern gas-fired heaters, where the heat is transferred through the inner wall, are generally not in need of flushing. Again, always worth checking every now and then.

Answer 3

Do I really need to flush my hot water heater?

It's a bit of a chicken-and-egg situation.

You don't know that you didn't need it flushed until you flush it.

One important sibling task of flushing it though is replacing the anode rod. This is a sacrificial rod which deteriorates to extend the life of your tank.

So at minimum the bottom of your tank will likely have remnants of the anode rod.

Answer 4

We've found it - necessary - to flush the hot water heater. We have a well water system, and there's some sediment and also the minerals that cook out of the water and leave deposits behind. In our case, it builds up enough to short out the heating element (we have an electric water heater), and it's either flush it or replace the water heater!
A clever plumber (unfortunately now retired) fashioned a sort of rake/spoon for us from a length of pipe (smashed down one end and bent it a little); I can insert it into the heating element space and scrape out chunks of build-up. (This may take quite a while - try to think of it as a Zen thing.) Last time I did this I dragged out over 8 cups (filled an 8 cup Pyrex measuring cup to the top) of what looks like dry, chunky oatmeal out of our water heater! Replaced he burnt out heating element, and we were back in business!