Re: Commodes gurgle
Posted by Charles Goodman on November 05, 19100 at 14:08:11:
In response to Re: Commodes gurgle
: Thanks in advance for your help. My home is about 5 yrs old, & we are on a septic system. The commode physically nearest the septic tank (but I don't know in what order they're plumbed) started gurgling a few weeks ago, usually when another appliance was using a large qty of water, & especially when the other appliance was draining. Now even the farthest commode gurgles, seemingly at random times. I have not noticed any change in the water levels.
: What's going on??
: Thanks!

My expericence, as a 40 year plumber, has been that when commodes start gurggling on a septic system the tank is full to the top or you have a blockage near the inlet of the tank. In either case the large amount of water draining into the pipe has to displace the air in the drain line. When the septic tank is at normal level, the liquid level in the tank is near the "invert" (inside bottom) of the inlet pipe. That means that there is a foot or so of air space from the liquid level to the inside top of the tank. Normally, the inflow of water will slightly compress the air in the top of the tank. When the tank is full-to-top there is no air and the liquid cannot be compressed, so the air trapped in the inlet line must travel back up the pipe (against the flow of water) and will exit at some fixture, usually a commode (thus the "gurggling" sound.
Phosphates from your soaps and powder may be coagulating to the consistency of "ivory soap" and blocking your tank inlet. If the septic is full-to-top, this phosphate is NOT a consideration and the problem probably lies in the "tight-line" from tank to first field line.
Hope this helps a little. Feel free to email me back (after checking items above) if you need to.
Best regards,
Charles



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