Can I run water lines through the attic?
The simple solution is to dig up the insulation, run the pipes along the top of the ceiling drywall (ie, just above the ceiling, rather than just below it), and put the insulation back on top of them, which puts them on the warm side of the insulation, "inside the home (thermally speaking)." Also to be a lot more careful when hiring "plumbers."

Otherwise, framing in a pipe chase below the ceiling would work, and might actually be easier in some cases (where crossing rather than running along ceiling joists.)