Boring one: gurgling drains

[EnterFunnyNameHere]

Sorry for how boring this is!

Sometimes (maybe every third time?) The loo is flushed in our main bathroom, there is a fair bit of "gurgling" which I'm reasonably sure is coming from the bath tub plug.

Water seems to drain ok from the bath itself when having showers etc, but is the noise maybe due to a blockage somewhere?? It feels like jumping the gun to get a plumber out, but don't want it developing into a big problem!

Sorry I have no advice but have the same here and looking for answers!

I have this problem occasionally. If I drain the bath or have a shower, the toilet starts gurgling.
We have a manhole on our driveway which next doors waste pipes also drain into.
On lifting the manhole cover, it's usually blocked.
So, have a look at your manholes.

Have you tried a drain unblocker from the supermarket? Just pour it down the bath plug hole, leave it overnight then flush with hot water. I usually find that gets rid of the gurgle.

How old are the main drains outside?