When a Gurgle After a Flush Cost Me My Basement: My Third Flood

https://www.canberratimes.com.au/story/9118615/top-plumbing-warning-signs-you-shouldnt-ignore/

When the first small gurgle felt like nothing: the build-up to disaster It started the way these things often do - with a sound you dismiss as part of old plumbing. I heard a soft gurgle after flushing the upstairs toilet. I shrugged it off