This is in the UK actually, not Thailand. I have a shower enclosure and the plastic drain pipe has a very small drop on it. It uses the crappy push together joints that seem so popular these days. Eventually the pipe bows and silts up slightly then one of the joints starts leaking. I replaced it a couple of years ago but now it is doing it again.
I can't do much about the slope, so what else can I do? I'd be happy with a continuous length of flexible pipe from the shower tray to the outside drainpipe but it seems you can't get it.
Any ideas from one of the many builders on the forum?