PEX tubing is increasingly replacing traditional copper and galvanized steel water lines in new construction and remodeling projects. But before you head to the plumbing aisle at your home improvement store and start working with it, be sure you understand all the rules. The most important rule is that you can only make a PEX connection at temperatures above freezing. If you connect it in the cold, you risk leaking for years to come.

Also, PEX expands and contracts with changes in temperature, so it’s best to keep it well insulated and protected against rubbing against something abrasive. And although PEX is resistant to most chemicals, long-term exposure to high concentrations of chlorine, excessive acidity or alkalinity and mineral content can shorten its lifespan.

There are three types of PEX tubing: PEX-A, PEX-B and PEX-C. The letters don’t refer to a quality rating, but rather the manufacturing method: PEX-A uses a peroxide curing process, PEX-B uses a moisture-cure process, and PEX-C is made using an irradiation method.

Red and blue PEX tubing is available to help distinguish hot from cold lines, and you can use push-fit fittings (view on Amazon) to connect it. The most common and preferred method, however, is copper crimping, which involves a series of copper rings that slip over the end of the tubing and fit into brass PEX fittings. A special crimping tool is used to deform the copper rings and hold them in place. pex tubing