Why does my basin gurgle when toilet is blocked?

When we have a lot of rainy weather my downstairs toilet tends to block up and can’t be used. (Upstairs toilet works fine.) The downstairs bathroom basin makes scary loud gurgling sounds especially when I flush the downstairs toilet. Is the toilet and basin somehow connected? If the rainy weather is the cause, wouldn’t that also block the upstairs toilet? I have tried plunging but this doesn’t work.

Jack - KT6

Asked: March 01 2018

Answers: 12