discolaration of poly pipe

What caused this pipe to discolor. It is a basement. The yellow pipe is further away from a window and the the whiter pipe in close to a window, same pipe by the way.

Polyethylene or what type of piping exactly is it? Well water or municipal?

Iron in the water

I would still like to know what kind of piping it is. I’ve never seen pex or piping (besides tubing) that you can “see through.”

See it all the time.

PEX is translucent. (Uponor/Wirsbo)

http://uponor.media-resources-ordp.com/2009/images/UP0928-PEX-Install.gif

I agree it looks like PEX to me too

The pex I see around here and that I’ve used, for potable water, is white-and not translucent. The other colors are red and blue. I’ve seen the translucent stuff use for radiant heating systems, but not for potable h2o. Can they both be used for either or?

Do they use Uponor/Wirsbo PEX in your area as shown in the picture above?

Pex can be used for both domestic water and heating loops however, you usually need Oxygen Barrier type PEX for heating uses to prevent damage to the heating source. (Exceptions apply)