I live in the bottom floor of a 5 story house, and we just got a new
main sewer drain pipe (a vertical pipe for bringing waste water out of
the house). That s very nice but somebody on the upper floors uses
water, then I get a lot of noise in my appartment. The pipe is
vertical, but it has a kink in my appartment, and I think this kink is
the reason for the noise. Sometimes the water falls down several
stories before hitting the kink.

I mailed the consulting engineer about it and he said that it is
normal for new drain pipes to be noisy, because they are clean on the
inside. Is that true? Is there anything the plumbers could have done
to reduce the noise?

I write here, because I don't know whether I should be pationt or
complain about the work. If I want complain it is a good time to do it
now, because the plumbers have not been paid yet,

Thanks in advance

Niels