The drain system is improperly vented or was set up to handle standard toilets. When the increased fast flow if the power assisted toilets is present, the vent pipe can’t supply make-up air quickly enough, a vacuum is created, and bubbling or gurgling occurs at the other toilets. These power assisted toilets came along when standard toilets couldn’t flush properly with 1.6 gallons of water. PATs have created their own set of problems. After 15 years , the manufacturers are finally offering functioning toilets that don’t need power assist.
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