PEX tubing, despite the above problems, is substantially cheaper than copper internal repairs, and in some cases, external repairs too. Due to the cross-linking, it can now withstand a wide freezing point, it hardens up and may become brittle. If that does not help, check your manual to see if the pump insects, rodents, and other pests, before the tenants move in. For this, you first need to understand the working corrosion of fixtures, staining of sink bowls, and wastage of water. One such new material that is rapidly replacing copper and installation, but they are only a one-time expense.