Answer this question without Google (Creative thinkers enter)

[Nikuk]

@The_Russian

I would imagine that since the local streams are connected to the lake, and the streams connect to the pipes to the house and those connect to the toilet, and fluctuation in water level in the streams or lake or anywhere inbetween would cause that.

wow… creative thinking, but no way in hell is there a direct connection between bodies of water & your shitter.