I've recently purchased a house and face a number of new challenges now. One of them is that water from the sinks goes out badly, and sometimes not at all (i.e. most goes out, but a few cm remain, for hours). Now one of the showers has started to show the same symptom.
The issue might have gotten worse (or I suffer from selective perception) after we removed the basement kitchen, which left one water outlet open (strong sewage smell, now the outlet is covered).
I've thrown the usual drain cleaner chemicals in there, to little effect, making me believe the problem isn't some hair in the outlet, but somewhere else. As I have no clue about plumbing at all, I don't even know where to start searching for the problem.
Two things that might help: One of the affected sinks has a plastic pipe under it, when I press it air bubbles come up and water goes out, so it seems air and not water is blocking the passage? Second, we are living in the house with 2 people. The previous owners were a full family (6 people living constantly, I think), so most likely there's now a lot less water going through the system. One shower and one bathtub we don't use at all.
Happy for any answers that can tell me how to troubleshoot the issue and finding out what the problem is.