Hot water tank was leaking yesterday but now it's not

Yesterday I heard dripping noises and thought it was my cat puking. But when he asserted his innocence, I investigated further and saw that it was coming from my hot water tank. The water was dripping from the fitting of the PVC pipe coming out at the top. There was a bunch of water pooling around the bottom. I said to myself, “Oh lord” and put down a bowl. Then I searched for the number to the maintenance guy. Apparently my landlord doesn’t believe emergencies exist and supplied me with only a fax number.

I took a shower last night and afterwards went to see if this caused anything catastrophic to happen in my utility room. I was relieved to find that the dripping had ceased. I’ve been trying to understand what happened and this is what I’ve come up with: The leaky pipe had hot water coming out of it, so I’m assuming this is the pipe that transports the hot water to my shower and elsewhere. By using a bunch of it, I made the water level in the tank fall below the pipe fitting so that it was no longer possible for it to “escape”.

Is this right?

I woke up four hours later and checked on it. Still dry. And now it’s 12 hours later and the leak still hasn’t returned. The hot water tank has presumably refilled (I still have hot water), so I’m thinking my hypothesis is wrong?

If I call the maintenance man, how is he going to know what to fix if there isn’t a problem evident?

The water tank it always 100% full. When you use hot water, it doesn’t “drain” the tank, it simply pushes out hot water with cold.

I suspect that the PVC fitting is loose. I’ve never heard of using PVC on a water heater, especially on the hot side. I’d worry about the connection loosening up over time. If you point out to the plumber where you saw the water coming from, he’ll be able to figure out what’s wrong (I hope…).

was this PVC pipe one that makes two turns and is open to the floor?

was this pipe the one where hot water goes into your house spouts?

if it is the later then it is always (as long as you have water and all the valves are open) has water in it.

if a leak stops it is just temporary. it needs to be fixed. if you need to shut off the water in your hot water system because of a leak then there should be a valve on the cold water inlet to your water heater (it should be marked or will be the pipe that is always cold). also good to know where the whole house water shut off valve. have the maintenance guy test both of them to be in good working condition when the maintenance guy fixes the leak.

johnpost, the leaky one is the first one you described, I guess? It has a couple of 90 degree turns and then goes down to the floor.

There’s another pipe nearby. For lack of better terminology, it has no angles. It also feels hot to the touch, whereas the leaky one doesn’t.

But the water that was leaking was hot. Perhaps it was coming out at the pipe’s connection to the tank rather than the pipe itself? It was hard for me to tell.

I’m going to call the maintenance guy, but I was just curious about why it was leaking and now it’s now. It’s really weird and my mind won’t let it go.

There’s an OTP (Over-temperature/pressure) valve on the water heater. It’s designed to release water in case the thermostat sticks on, and starts to boil the water. Those have been known to leak. You can tell, because the pipe will go to a drain. Also, the OTP pipe will look different from the inlet and outlet pipes, which will be parallel to each other, and at the top of the tank.

The valve and pipe you describe is the temperature and pressure relief valve. It is a safety feature… if the temperature and/or pressure in the water heater gets too high, it releases some of the (hot) water out to bring it down.

If the pipe leaks water, it means it is doing its job. But you still need to call someone to figure out why the tank was building up excess pressure and get that fixed… you should not rely on the safety feature for an extended time.

That pipe is connected to the pressure relief valve to redirect any discharge in a relatively harmless direction. Apparently you had a situation where too much pressure built up in the tank so the pop-off valve did it’s job to release the excess pressure then closed again once the pressure normalized. Not a problem if just a one-time thing, but if it continues to happen with any sort of regularity you’ll need to determine why it’s over pressurizing. Did anybody turn up the temp setting recently?

Dang, ninja’d not once, but twice. Need to type faster.

beowuflf, that’s it! :slight_smile:

as stated that is the OTP valve.

maintenance guy can fix the leak and replace that valve if needed.

have the maintenance guy test and show you the whole house water shut off valve, hot water tank cold water inlet shut off valve and the OTP valve on top of the water heater. it is good practice for you to test all these once a year.

Oh, thanks for the other responses too! No, I didn’t adjust the settings on anything.

That’s good. I think some posters are thinking of the Mythbusters experiment.

the OTP valve also called TPR (temperature pressure relief).

the OTP (TPR) valve should only release water near the floor. if you see water on top of the heater then there is a leak that should be fixed. also the valve may have failed to open as intended.

tell the maintenance guy what happened so the maintenance guy can diagnose the problem. comments here from afar are good to aid you in understanding .

It’s been my experience that of the T&P valve starts leaking, the rest of the heater is not far behind. If the heater is old, replacing the T&P valve will buy you a couple months before some other part fails.

I was going to say this. I hate to be the harbringer of doom, but we have had thre tanks go on us (different houses). They all started with a little trickle.

There may have been a situation where a lot of water was being used then immediately shut off which can create a pressure ‘shockwave’ called water hammer which may be enough to trip that valve. This also can be done at the street level if a hydrant was opened then shut suddenly, a high pressure surge could have traveled into your pipes.