Toilet tank overflows when sprinkler is on

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Old 07-22-19, 07:50 AM
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Toilet tank overflows when sprinkler is on

I recently discovered that my one of my toilet tanks overflows when one of the four zones of my sprinkler system is running. The tank (one of two on the first floor of the house) just keeps filling until it starts running out of the top. This does not happen when the other three zones are on and the toilet runs fine otherwise. Probably not relevant, but the sprinkler zone is on the opposite side of the house from where the toilet is.

Any idea what is going on? I suspect I will have to call a plumber but would like some idea of what might be happening before I do so.
 
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Old 07-22-19, 09:41 AM
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I would replace the toilet fill valve.
 
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Old 07-23-19, 09:34 AM
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toilet tanks overflows...
Overflows as in keeps running and drains into the bowl? Or actually overflows onto the floor?

If it's ending up on the floor, something else isn't set up correctly. A toilet tank should never overflow. If it keeps running, it should run into the overflow tube into the bowl. A waste of water, but nothing damaging.
 
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Old 07-24-19, 08:59 PM
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I will look into replacing the fill valve, but my real question is, why does this only happen when the sprinkler is on? (And with only one of the four zones, at that.) I would think that, if the fill valve were defective, every time I flushed the toilet it would overflow.

And to answer Zorfdt - it is the tank that overflows, and yes, it goes on to the floor, not into the toilet. But again, only when the sprinkler is on - not when I flush the toilet.
 
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Old 07-24-19, 09:46 PM
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Those toilet fill valves require a certain water pressure to operate correctly. Apparently.... that sprinkler zone is using more water than the others and dropping the house pressure too low.

Your toilet should be set up with an fill/overflow pipe. The water in the tank should never rise above that pipe. The diagram is basically an older toilet but most are set up similarly. The blue line represents the normal water level. If that should rise..... the water will run into the overflow tube.

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Old 07-25-19, 03:23 AM
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Apparently.... that sprinkler zone is using more water than the others and dropping the house pressure too low.
I'm not saying you're wrong, but it sounds counter intuitive. If water pressure drops and the fill valve is defective the water will continue to flow into the tank slowly and slowly go into overflow valve. However, if the sprinkler system is pulsating or providing some kind of back pressure I can see a high pressure surge take place over whelming the fill valve to force it open and gushing water into take and overflow can't handle it.

I would first shut off the water supply to the toilet and run the sprinkler to see what takes place. Do any other water appliances get affected? Then replace all internal toilet parts. And as a last resort provide a new water source (divorced from the sprinkler zone) for that toilet.
 
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Old 07-25-19, 04:29 AM
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Many modern fill valves are a solenoid type valve. They rely on the water pressure as hydraulic pressure to provide the power to both open and hold the valve closed. Low or pulsating pressure can cause trouble.

If water is leaking out onto the floor than the toilet is set up very wrong. As PJmax pointed out any excess water should go down the overflow tube, into the bowl and down the drain. I have seen people install taller overflow tubes and even one where they plugged it and run a higher water level in the tank as an attempt to improve the flush or make up for other clogging problems.
 
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Old 07-25-19, 07:52 PM
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And as a last resort provide a new water source (divorced from the sprinkler zone) for that toilet.
How would you do that.
Most if not all homes have one water supply line.
 
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Old 07-25-19, 10:01 PM
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I'm going to try shutting off the water supply to the toilet and see what happens. Torrential downpours for a few days so sprinkler has been turned off. Will turn it on again tomorrow.
 
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Old 07-26-19, 03:14 AM
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How would you do that.
Most if not all homes have one water supply line.


Not very easily.
Like I said as a last resort if no other solution is found. If it's on an upper floor almost impossible , but if it's on 1st floor with a basement not too hard.
 
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Old 07-26-19, 10:00 AM
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And to answer Zorfdt - it is the tank that overflows, and yes, it goes on to the floor, not into the toilet. But again, only when the sprinkler is on - not when I flush the toilet.
I'd say you have two issues then. All tanks should have an overflow preventing water from ever ending up on the floor (short of a clogged drain).

Can you take a picture of the inside of the tank? Something sounds like it isn't quite right.
 
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Old 07-26-19, 02:37 PM
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New fill valves are $10. Sure sounds like an easy solution.
 
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Old 07-31-19, 07:59 AM
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As requested, photos of fill valve.
 
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Old 07-31-19, 08:18 AM
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I have been reading about sprinklers systems, Someplace in this artical is something about your problem, I think it was about 5 or 6 pages in.
https://www.irrigationtutorials.com/...sign-tutorial/
 
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Old 08-05-19, 06:40 AM
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Tried to post pictures of the fill valve, but it doesn't seem to have worked. Is there not a way to upload photos from my computer? The "Image" icon seems to require a URL, and I don't have a site to load the photos on to.
 
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Old 08-05-19, 01:30 PM
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Until the web masters resolve this and many other problem use a hosting site such as IMGUR.
 
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