[LazyPup]

It is very unlikely that the taste in the water can be attributed to the pipe. All materials approved for potable water supplies are tested to insure that they are stable plastics or metals that will not introduce odors or tastes into the water supply.

You may use PEX as well as copper or CPVC for the above grade water system, however, PEX is only code approved if all joints are made with the code approved crimp on type fittings and then only if those fittings are made up using code approved crimping tools. (there are about 5 different sizes of the tools commonly used in residential plumbing and they cost $125 each)

I would strongly encourage you to have the water tested, especially in a camp cottage because no doubt the water stands in the pipes for extended periods of non-use and chemicals, minerals or bacteria is especially problamatic under those circumstances.