My hot water heater developed a leak bad enough that the towels placed on the floor around it need to be swapped out every three hours or so.

I've shut it off and depressurized it by turning off the cold water feed and opening a hot water tap at a nearby sink, but I haven't drained it yet.

I found that this was enough to stop the leak, or at least reduce it to a tiny fraction of what it was previously.

It could be a long time before I can get it replaced (I want to switch to an electric tankless heater, but that means getting a lot of electrical work done first).

Since the tank isn't drained, is there any reason not to turn the heater back on and keep it hot? Then I could briefly turn the supply line back on to take showers and wash dishes, and then turn it back off when done.

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    You might not be happy with the power bills from electric tankless. Would be something to check into more. If the leaking tank is electric, then the problem is making sure the heating elements are always covered with water. They blow/burn out if in the air/dry/water drains below them.
    – crip659
    Jul 4, 2022 at 18:28
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    Current tank is gas, but my long-term plan is to switch the house to 100% electric and get rid of our gas service. (Furnace and hot water heater are currently the only things that use gas.) Jul 4, 2022 at 18:45
  • Looks like all energy bills will be increasing. Check out Solar water heating.
    – Solar Mike
    Jul 4, 2022 at 18:55
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    @EdwardFalk You're not going to able to power an on demand electric WH with solar electric. If you wanted to go solar and have the climate for it, do solar hot water panels. much more efficient. Jul 5, 2022 at 0:58
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    Tankless electirc is incompatible with power outages. If you put in solar (electric) panels, you'll likely have enough power to keep an electric tank heater going for moderate usage (perhaps 30A part of the time), but you'll never get enough power to run tankless when the utility power is out (100A very little time, but when you need it, you need it all at once - and that's a lot of panels). Jul 5, 2022 at 1:48

2 Answers 2


Yes you can if you leave the power on make sure the leak is not severe enough to expose the upper element if left powered on.

I have installed quite a few electric on demand water heaters and most customers were not happy with the end result even after adding additional point of use units to better regulate the water temp(but you never run out of hot as long as there is power)

I would recommend a heat pump style water heater, I got mine basically for free (utility rebates) as I was able to hook it up, it works much like a conventional unit but uses a high efficiency heat pump to heat the wate.

1 caution here but can be a plus, if you can vent the heat pump out side in the winter and inside in the summer it will really help your power bill but if inside your heating bill will just about offset the winter savings but summer it ends up being less or your house is cooler if you don’t have AC.

Heat pump water heaters have similar recovery problems to conventional electrics as far as the recovery time, but if you need to replace check into possible utility company rebates, as I said I got the cost of my unit basically for free by purchasing the one the utility offered. It has been a few years now and I miss my on demand gas water heater but after all the cost and complaints from customers that I hooked up electrics for I am glad I have the heat pump.

  • I actually have a pair of Stiebl 15+ heaters in a cottage and have been very happy with them for the last few years. But I will certainly consider getting a heat pump for my house. Jul 4, 2022 at 19:38
  • @Edward Falk, I like the smaller point of use ones I have one in my barn to wash horses, I loved my Gas on demand, but with so many complaints from customers on the whole house electric on demand I only upsized my service to 200a when I replaced it and not the 250/300 it would have taken.
    – Ed Beal
    Jul 4, 2022 at 19:47
  • Yeah, I'm looking at the Stiebl 29 for my whole-house heater and they recommend the house have 200A service and I need to run three 40A lines to the heater. The heat pump unit I'm looking at only requires 30A so it's looking more attractive the more I look. Jul 4, 2022 at 23:40
  • My original water heater was 240-30a so I was able to use the same lines as the original (10 awg 3 wire) .for the heat pump. The largest electric on demand took a similar size but we had to go to 300 minimum for that service and we added point of use and he still was not happy, pulled it all out and installed a big tanked electric.
    – Ed Beal
    Jul 5, 2022 at 0:06
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    +1 I've been on a few calls where people with 150 amp mains were talked into installing a tankless. Someone taking a shower, the strip heater kicks in, the dryer starts up and they trip the main. I've removed some and put back the standard water heater.
    – JACK
    Jul 5, 2022 at 16:09

There is no reason not to turn it back on.

It is already destroyed (leaking), and heating from outside (with gas) should not be a problem. There should be a thermal element that turns of gas at set point.

The keeping pressure during use might be tricky.

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    Well, it's gas, so the heat is all at the bottom. I have that going for me. With the pressure off, the leakage is near imperceptible. Jul 4, 2022 at 19:31
  • @EdwardFalk Absolutely correct, so do it ! can you find the leak >
    – Traveler
    Jul 4, 2022 at 19:34
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    I've read that if the leak isn't obviously from the drain valve or pressure-relief valve, then the problem is the tank itself which can't be fixed. Jul 4, 2022 at 19:38
  • Shouldn't be a problem keeping up the pressure during use since the OP stated they'd turn on the supply during use.
    – JACK
    Jul 5, 2022 at 13:32
  • @JACK OP also stated it leaks like Niagara falls if pressure is increased
    – Traveler
    Jul 5, 2022 at 17:10

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