Generally, these days, flexible PEX (cross-linked polyethylene) piping is used for new work in most places. I don't think pressure loss would be much of a probl

Generally, these days, flexible PEX (cross-linked polyethylene) piping is used for new work in most places. I don't think pressure loss would be much of a problem since the curves in a properly installed system should have a reasonable radius. The reason copper is still used seem to have more to do with inertia and a (sometimes warranted) lack of confidence in new building products.