In my downstairs cloakroom I have the mains water coming in and a stop
cock in the room. The piping then runs along the wall and then up and
into the ceiling. It is pretty unsightly and I want to hide it by
chasing it into the wall. The problem is that it is old steel piping
which is not going to be too easy to manipulate.

What i want to do is replace a section of the pipe with plastic or
copper (probably plastic due to the corrosion problems) but how do you
connect steel piping to plastic piping? Is it possible?

I really don't want to replace the entire thing as a quick decoration
of the cloakroom is rapidly turning itno a huge multi-room job!!

Any thoughts?