septic tank question


Old 11-12-19, 02:20 PM
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septic tank question

I came home today to find a toilet had been running for hours. While no damage was done I am sure there is a limit to how much effluent my drain field can take. Should it have become saturated I suspect the water would have backed up into my basement tub and then begin to overflow. I do not want that to happen.

I have a 4" pvc line going into my tank and I have a clean-out plug in some shrubbery between the house and the tank. Is there some kind of flapper or valve I can install in place of the clean-out plug that would contain the smell but allow backflow to leave the line and avoid a backup into my basement?
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Old 11-12-19, 02:30 PM
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If it isn't backing up now I wouldn't expect it to start. I would try and limit water usage until the field has had time to dry out some.
Old 11-12-19, 02:44 PM
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Yes, you wasted a lot of water but that's generally not the sort of thing that causes a backup. I would not try re-inventing the wheel for such a rare occurrence. Plus, code does not allow devices that dump raw sewage. If it backs up you fix it immediately. If you have an alternate like overflowing outside you are more likely to put off the fix. Not to mention dumping sewage on your lawn.
Old 11-12-19, 04:22 PM
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It is pure guesswork as to when the water from the running toilet is absorbed by the drain field (leach field) but I would guess that if you wait 4 hours with no use of water then everything will be back to normal.

Under normal conditions the septic tank remains about 85% full of solid and liquid, and for every gallon of waste water coming from the house, one gallon exits for the leach field. The leach field has a gallons per minute (unknown variable) absorption limit. If the GPM max is exceeded then the air space in the leach field piping will start to fill up. Next the remaining 15% of space at the top of the septic tank will start to fill up. Finally the water will back up into the house. (These air spaces will not fill completely with water because the trapped air pockets within will not compress to "nothing" as more and more water enters.)
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