Just wondering if there are any DIYers plumbers that can help me figure this out?
If draining a full tub of bath water causes multiple sinks and toilet in one area of the house and (not another area of the house) to gurgle and bubble but drainage itself does not seem that impaired, would this indicate a problem / blockage with the vent pipe? Or could it still be a partial clog in the main drainage pipe for that area?
Just recently
Same thing happened to us last year and it ended up being the sewerage(?) pipe blocked with tree roots and had to be cleared by a plumber.
We had the same on our new build - turned out sewer pipe was partially blocked. We had gurgling and ticking/burping noises.
While you say the water drains, it'll only drain until the spare capacity in the system is exhausted and then may overflow (assuming sewer blockage is the cause).
Hmm…so there's no slowing of drainage at any of the sinks. The bath drains at full speed (several tubs ~200L worth drained since the problem started to occur).
You have a partial blockage. Nothing to do with the vent pipe IMHO.
If it drains slowly then do you have and trees where the roots could get to the pipes under/around the house?
Is the kitchen anywhere near the affected area? Could be a fat blockage.
If you want to try to unblock it your self then go to Bunnies and grab a few liters of drain unblocking stuff and try it, but if it's roots then it may help for a little while (a few weeks to a month or two.
Drainage does not appear to be slowed…
Ok I think you may be right. I checked the roof and there is no vent pipe up there but there is an external sewer hole that is clogged with soil and when I flush the toilet, water appears there so I assume that is the issue. I tried drilling through with a broom handle (it's about 1m down) but its very hard. Would it be reasonable to try a high pressure hose to get through? (ps I have also called a plumber to attend but they can only come next week so figured I'd give it a crack in the meantime).
I have something like this which is very handy if the clog is not too deep and hair. https://www.amazon.com.au/FlexiSnake-Snake-Drain-Rotating-Mi…
I purchased something like this
https://www.ebay.com.au/itm/302669994064
to clear a slow drain in some old steel pipes where it wouldn't have been wise to use corrosive chemicals.
Did a remarkable job - handles hair, mud and almost anything else that gets in the way … but not tree roots, those suckers are tough.
If it gets stuck, the coil backs up behind the head and scours the pipe walls, which is handy.
I've also used it to clear blocked stormwater pipe (90mm PVC); took a little more effort but loosened the mud enough for back pressure to wash it out.
Has it always done this or just recently?