I turned off water to two of the three toilets in my house because they started leaking. By doing this, does this affect water pressure in say the shower?

The one toilet has been off for a year and no issue. But the other I turned off this morning around 4am because it started running constantly.

All of a sudden about 515am, my shower starts dripping like crazy. So I turn on the shower and it shot out real fast for a split second. Was this just a coincidence? Or does turning off water to toilets affect water pressure in other items that use water?


  • One possibility: Note that many toilets have a float valve setup where increasing water pressure (due to expansion caused by heating) can cause the toilet valve to open briefly, thereby lowering the water pressure. Most other valves cannot do this, so without toilet valves the pressure (if caused by heat expansion) can greatly increase.
    – Hot Licks
    Nov 14, 2022 at 13:45
  • 1
    You had some air in the line. It acts as a spring until it's released.
    – isherwood
    Nov 14, 2022 at 14:58

4 Answers 4


Turning off water to toilets won't make any difference in your shower. Thinking thru this: What's the difference between the toilet itself shutting of water when the tank is full vs turning off the supply to the toilet? NOTHING! So that's not the source of your problem.

What sort of water heater do you have? Tank type? Is there expansion tank somewhere near the WH? The reason I ask this is in a home my son was living in, the water company replaced the meter and added check valves to prevent back-flow. He called me, concerned that the he'd get sudden spurts of high pressure at times and that the Temp/Pressure valve (TPV) on the WH was leaking. He said it usually happened after doing laundry or taking showers. I asked him to get one of those inexpensive pressure gauges and put it on an outside hose bib. Sure enough, the pressure was spiking to over 100psi. The TPV was on the WH was doing it's job. This was caused by cold water entering the WH, getting heated (which makes it expand), with now (given the new check valves), no place to go so the pressure went up. Adding an expansion tank fixed the problem.

If this is your problem, the high pressure probably overwhelmed the shower valve. For further diagnosis, does the "spurt" happen from any faucet? Does it continue to leak after the short spurt? Like I told my son, you should consider getting a simple pressure gauge which are usually available in the plumbing/sprinkler system area of a big box store. attach it to a hose bib and see what kind of pressures you're dealing with.

That's just one possibility that I personally experienced. Crip might also be right in that if you have a pressure reducing valve it might be failing , but I would not expect that to be intermittent.

  • 1
    And if there is an expansion tank, check to make sure it is working correctly and/or the pressure of the bladder is correct. I had an expansion tank fail and the symptoms were increased water hammer and sometimes the spike in pressure when turning off a faucet was enough to force the one of my toilet valves to run for a second or two. I can imagine that if a shower valve only seals "ok" that a spike in pressure could cause some water to push by.
    – beswald
    Nov 14, 2022 at 16:01

If you turn off the water supply to the whole system for a bit, drain the lines to do some work, then turn the supply back on, some spurting from the faucets is normal.

  • I just turned the water off to two toilets. I never touched the system water. Does this change pressure in the shower?
    – Brian O
    Nov 14, 2022 at 11:02

If the toilet was leaking bad, it will reduce the water pressure to other fixtures, but will not increase the normal house water pressure if the leak is stopped.

Would maybe have the water pressure coming into the house checked. Some houses on city water have a pressure reducing valve near where the water comes in. It might not be working right and letting to much water pressure in.

  • I doubt a badly leaking toilet would measurably decrease water pressure in the home, But why not just fix the damn toilet? Toilet guts are usually less than $20. If this continues, what's really going to leak is his bank account paying the water/sewer bill! Nov 14, 2022 at 16:39

I would get a pressure check of your incoming water supply. Also I would say all your water appliances are old and in need of replacing. When you shut off water appliances in the system it will increase pressure on other fixtures. As you are shutting off a leak that is lowering the water pressure. Hope this helps.

  • 3
    How can shutting off some appliances cause an increase in pressure?
    – Hot Licks
    Nov 14, 2022 at 13:48
  • Steve, you have NO WAY of knowing his "water appliances are old and in need of replacing". Even if they are old as dirt, they couldn't be causing the symptoms the OP is describing. Nov 14, 2022 at 16:30

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge that you have read and understand our privacy policy and code of conduct.

Not the answer you're looking for? Browse other questions tagged or ask your own question.