Why is my toilet overflowing in the middle of the night?
Higher municipal water pressure overnight can cause the water level to rise uncontrollably and flood the floor through the flusher handle or overflow pipe. While lowering the fill valve and overflow pipe stops the immediate mess, it leaves homeowners worried about whether running a lower water line is safe or correct.
What people tried
Every workaround mentioned in the threads below. We haven’t tested any of them — and nobody here is claiming they worked.
Found another way around this?
Share your steps and trade-offs so fellow engineers don't have to reinvent the wheel. No account required.
Why is my toilet overflowing in the middle of the night?
- 1Get a new flapper and fill valveDid this help you?
- 2Lowering the fill valve and overflow pipeDid this help you?
- 3running a scope into the pipes to check for blockagesDid this help you?
- 4inspecting the pipe pitch and standing water under the flangeDid this help you?
- 5Calling the water company to report the issueDid this help you?
- 6Checking for a clog along the main drainage lineDid this help you?
In their words
Unedited, grouped by where they were said, most upvoted first within each place, each linked to the thread it came from.
“i lowered fill valve and lowered the overflow pipe because i was trying to figure out why the water was raising too much at night and overflowing through the flusher handle.. last night it seems to have overflow through the overflow pipe now that it’s been lowered… but now im worried or wondering if its ok for the water line to be under what it was before… help!”source ↗
“this is what i would wake up to in the middle of the night early am because im assuming of higher municipal water pressure.. because during the day the water line was at the CL.”source ↗
“We have two bathrooms on our second floor that are back to back (master and hallway). There is also a toilet upstairs on the third floor if that matters. The one in the hallway rarely gets used (maybe once a week or longer) but the other gets used daily(Master). A couple of days ago we flushed the one in the hallway that rarely gets used and it not only backed up but overflowed all over the floor.”source ↗
“water forcibly leaving the bowl, and a scent of sewage gas. It went on for about 10-15 seconds. It then happened again 15 minutes later, and then one more time about 10 minutes after that.”source ↗
Where this came up
People with this problem also raised
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- 22Why won't my toilet stop running?
- 6Water leak from screw after flushing water heater