My water heater (gas) shows a date of 1991 on it, although the house was built in 1993. There is nothing wrong with it. It is a little slow to heat the water up, sometimes taking almost 5 minutes to provide hot water (early morning, colder nights) but other than that there is no problem.

I hear that one should be replacing the water heaters every 20 years. Is this true? if it breaks, its going to flood the surrounding area. I dont want to replace it unless I have to. How can I check on this?

UPDATE: Based on the inputs, I have decided to replace the water heater. It may be a $250 for the check/clean/replace the rod/valve/sediments that I can add to the purchase of a new one and not worry about it for the next few years.

full image close up heat setting knob

  • A picture of the heater in question might help people form an opinion.
    – Stephen
    Jul 22, 2011 at 12:54
  • i'll add it tonight.
    – coder net
    Jul 22, 2011 at 14:45
  • From the photos, it looks like you had it set pretty low, and there's no obvious bulging or corrosion that would be big warning signs.
    – Stephen
    Jul 23, 2011 at 22:27
  • 2
    Regarding the update: Good choice, imo. Might want to put something on the new water heater as a reminder to change the anode rod in 6-8 years. Test the T&P relief valve annually... just have to pull on the handle. If water comes out, it's ok -- if not, replace it immediately. I'd replace it at 20 years whether it works or not, though. Doesn't make much sense to risk your life/house (even if it's a small risk) in an attempt to save $15. With some minor maintenance, a water heater can safely operate for 30-60 years. With no maintenance, it will dangerously operate for 10-25.
    – Michael
    Jul 26, 2011 at 23:09

4 Answers 4


The fact that it is taking 5 minutes to deliver hot water to the shower rarely has anything to do with a tanked water heater and is instead because of the distance between the water heater and the shower. (Also depends on whether or not those pipes are exposed to the elements, as the hot water will have to first heat the cold pipes before it can deliver hot water to the shower. Raising the temperature setting would help heat the pipes faster, but that would nonetheless be a problem with the setting, not a problem with the water heater that would warrant replacement if it were the only problem.) That aside, either the water at the top of the tank is hot or the water heater simply isn't working. (Hot water, like hot air, rises. If there's one place that hot water should be at, it's the top of the tank, which is where the hot outlet draws from.)

Water heaters typically go bad for two reasons:

(1) Not changing the anode rod, leading to corrosion that eats through the tank. If you haven't had your water heater's anode rod replaced (typically about every 10 years), then this thing is a ticking time bomb, and it will fail very soon.

(2) Sediment covering the electric elements / gas burner, at which point performance will be reduced. This will often cause "popping" noises, as the elements get quite hot and then cause water trapped within the sediment to almost instantaneously boil, causing a tiny explosion as the water turns to vapor. In electric water heaters, this will pretty much cause the lower element to be completely useless, as it becomes buried under more and more sediment, either becoming thermally insulated from the water that it's supposed to be heating or outright failing due to excessive temperatures. The common symptom of this in electric water heaters is that the hot water will quickly run out, as only the top element is working, and the hot water stays near the top. I haven't worked with gas water heaters much, but the logic is pretty similar... sediment and scale is going to cover up the surfaces that are transferring heat from the burner to the water, and you're going to lose a lot of efficiency. (To make matters worse, your water heater probably only had about a 50% AFUE [annual fuel utilization efficiency] rating when it was new, and if it has any sediment problems, it's probably down to 25%. By contrast, a new gas water heater will have 75-90% AFUE. Ergo, I would say it's worth it to change the water heater on account of efficiency alone.)

Note: Some of this depends on location -- the harder the water, the worse these problems will be.

If you don't have a water softener, you should immediately replace the unit.

If you have a water softener, the unit might still have problems, and even if it doesn't, I would replace it on AFUE concerns alone. If you don't want to replace it, though, you MUST at least have a plumber come install a new anode rod and T&P relief valve if you have not had the water heater serviced recently. (If your T&P relief valve is scaled over or has otherwise failed, flooding should be the least of your concerns. A failed T&P valve can lead to a BLEVE [a type of explosion], which would pretty much flatten your entire house and possibly kill everyone in it. See below.)

enter image description here

PS: What you want to use as a temperature setting is up to you, but you should keep it at at least 120-125F, raising the temperature up to 140 degrees Fahrenheit once a month to ward off Legionnaires' disease, which carries a 30% fatality rate.

  • 1
    +1 for lots of great points. Here's a good video on replacing the anode rod: thisoldhouse.com/toh/video/0,,20047047,00.html
    – BMitch
    Jul 24, 2011 at 1:06
  • 3
    And this is why you don't want a broken T&P valve: youtube.com/watch?v=9bU-I2ZiML0
    – BMitch
    Jul 24, 2011 at 1:10
  • thats pretty scary information. I live in Maryland and has only been in the house for last 3 years. how can I find out when the anode rode was replaced last? i don't see any notice on the heater.. also, what is a water softner, is that associated to the heater or the main water supply?
    – coder net
    Jul 24, 2011 at 17:43
  • The anode rod is a sacrificial rod that bears the brunt of the galvanic corrosion caused by hard water. When it's gone, the water starts eating away at the tank. BMitch linked a video on how to do it, but as the video illustrates, changing out an anode rod typically takes some serious muscle. Probably the only way to check it is to actually remove it and see what it looks like. You could also use an exploratory camera to look at the anode rod, but it would have to be pretty good quality, which means it might be pricy. Best to just get a plumber to replace it and the T&P valve as well.
    – Michael
    Jul 24, 2011 at 18:49
  • In regards to what a water softener is, it's an appliance/device that replaces the calcium and magnesium found in hard water (both hot and cold, not just something that filters only the water heater's water) with sodium. Doing this prolongs the life of your water heater and other plumbing and also eliminates calcium/lime build-up in the shower and on sink fixtures.
    – Michael
    Jul 24, 2011 at 18:55

You may have the thermostat on your heater set too low. Gas heaters are either on or off; when they're on, they can really make that water nice and toasty in a hurry. Check the thermostat and the temperature of the water in the tank (if you don't already have a temperature gauge you can read on your tank, this may require professional help as the tank will be under normal water pressure even if the water's stone cold).

You may also need to flush out the tank; sediment can collect at the bottom over many years and reduce the efficiency of the heater.

A 1991 water heater is approaching the end of its rated life, but ratings tend to be pretty conservative on these types of things. I wouldn't be surprised if you got another 10 years out of it. The one I have is the original in a 30-year-old house, and it works just fine, but we have the money for a new one sitting in savings just waiting for a hiccup. Ours is also in a garage (I'm in Texas, so no basements, just a slab on grade or in really soft-soiled areas pier-and-beam), so even if it fails completely and drains out it's not going to cause much damage (just a big ol' water bill and a few cold showers).

  • ok, i'll flush the water heater and see. I see some instructions/videos online for this. Is it safe for me to do it? I really have no experience with these.
    – coder net
    Jul 22, 2011 at 14:19
  • Also, what is an ideal thermostat setting. I think mine is analog and I put it somewhere in the medium high. I'll confirm that.
    – coder net
    Jul 22, 2011 at 14:26
  • Personally I would keep my hot water at about 110*F at the tank. This is hot, in fact painfully so to most people, but is unlikely to scald, as skin must be exposed for several minutes for even a first-degree burn.
    – KeithS
    Jul 22, 2011 at 14:34
  • I added some pics of the heater as requested. The setting was on the small mark near the "warm" setting. I moved it to the next longer mark. Its a lot hotter now, but I have to still evaluate about the pace of heating for the next 2 days.
    – coder net
    Jul 23, 2011 at 21:43

I agree with most of what KeithS said in his answer and I would only add that when I saw the particular symptom of slow heating in my hot water heater the cause was a fairly substantial amount of sediment inside the base.

If the tank is in general good health, flushing could solve this problem, but depending on the severity it could have also stressed a lot of the parts.

When making such a decision I personally balance the cost of a new unit, installed, against the cost of a service call to have someone give it a once over/tune up, the general health of the unit (yours seems fairly healthy), the odds of having a failure and the cost associated with a failure (is it in a spot where it would cause a lot of damage if it ruptured?)

If you think you'll see another 5-10 years, it's probably worth having it serviced.

Hope this helps.

  • Yes, part of the problem is determining the odds of it failing. If it fails, it will flood my basement and there will be some damage much more than what I'll need to spend on getting a new one. The problem is how to know if its reaching its limit.
    – coder net
    Jul 22, 2011 at 14:21
  • I would check the temperature setting as suggested above, if it's already highish, then you've likely got a sediment problem.
    – Stephen
    Jul 22, 2011 at 15:54
  • Added some pics, increased the heat setting a little more. Will observe for a couple of days.
    – coder net
    Jul 23, 2011 at 21:43

Replace it, cheapest $800 - $1,500 you'll ever spend. Twice I've had water heaters at end of life, 15-17 years old, working absolutely perfectly until they weren't. Both times I was overseas when I got the word the lower level was full of water, everything ruined. One was a tenanted rental property so had to arrange replacement remotely ASAP.

I'll keep my cars and trucks running over 200K miles but I don't mess with water heaters. Think Faulkner..."...a mule will gladly serve you for 10 years without complaint just to have the pleasure of kicking you once."

  • That's only the EOL if you treat your water heater like a 'shroom, man. Jul 29, 2016 at 3:32

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