Hopefully, the plumber "vented" the upstairs tub drain like in the picture above. If not, it would create the problem you mention. Terry

: I fitted a replaced a tub in our flat , where it was previously unused. We are three floors up and since then my lowest neighbour finds some regurge.

: Plumber told me that the waste stack was quite clogged and he told me that the only real way to prevent the regurge below was not to open the pop-up waste fully and let the tub water drain more slowly - otherwise a whole new waste stack would be needed by everyone eventually.

: Is this true - or does anyone have any further thoughts.

: Would it be worth lower neighbours fitting a anti-regurge valve or are they dangerous?

: Cheers,

: Keith, MA