Can the rusty iron pipe be sawed off and connected to the plastic tube?
The two scheme, if the specifications of the iron pipe, and not big, in 2 inches below, there are ready to buy quickly, buy a back and plastic pipe butt. If the iron pipe is too big or not in the specification, use pig iron to weld the mouth of the tooth you need.
If you do not consider late, you can, but if you take into account the use of the latter, it is best not to affect the future maintenance of water quality, safety and other issues
It depends on the rust of the pipe. It is not weak or serious. The iron pipe is sheathed wire, one end of the pipe is connected with a plastic heat wire connector