The one thing I have tried to do about this is use those foaming and non-foaming drain unblockers regularly. That has just been money down the drain, pardon the pun.
I suspect that unblockers only work if the blockage is in trap (the first bendy bit that blocks smells). I suspect my blockage keeps occurring elsewhere, because when the washing machine flushes copious amounts of water, it has no problem coming out of the bathtub drain - so clearly that part isn't blocked.
I've also tried the plunger (which occasionally helped to unblock the pipes, and always helped get the 30 minutes daily exercise), and a snake (long bendy cable thing), which has been a complete waste.
My questions: is there anything else I can try or is it time to call a professional? Also, does this sound like some sort of a design problem with the pipes in my flat, or is this just the way drains always are? (hope not!...)
I have since learned the following things about my waste pipes, which together explain the constant blockage and glugging sounds:
- The pipe is far too narrow for a tub, two sinks, a dishwasher and a washing machine: only 4cm.
- There's a very sharp 90° bend near the exit from the property, which is where a huge blockage accumulates (10cm deep solid chunk of waste). Apparently a waste plumbing no-no.
- Most of the pipework lies flat on the floor, with zero slope. There's about 1.5m of it that is visible. Apparently against all plumbing codes and a cause of blockage.
- There was a T-junction installed "backwards" (directing incoming water from a sink towards the kitchen appliances and forcing it to reverse direction in order to leave the property). There was a humongous second blockage underneath this T-junction.
- There is no air vent (really!), explaining the noises. (update: the noises went away once the second blockage got eliminated)
Overall, a really bad plumbing job someone did here...