Galvanized pipe (galv)
Galvanized steel potable water supply and distribution pipes are commonly found with nominal pipe sizes from 3⁄8 inch (9.5 mm) to 2 inches (51 mm). It is rarely used today for new construction residential plumbing. Steel pipe has National Pipe Thread (NPT) standard tapered male threads, which connect with female tapered threads on elbows, tees, couplers, valves, and other fittings. Galvanized steel is relatively expensive, and difficult to work with due to weight and requirement of a pipe threader.
It remains in common use for repair of existing “galv” systems and to satisfy building code non-combustibility requirements typically found in hotels, apartment buildings and other commercial applications. It is also extremely durable and resistant to mechanical abuse. Black lacquered steel pipe is the most widely used pipe material for fire sprinklers and natural gas.
Copper pipe and tubing was widely used for domestic water systems in the latter half of the twentieth century. Demand for copper products has fallen due to the dramatic increase in the price of copper, resulting in increased demand for alternative products including PEX and stainless steel.
Plastic hot and cold supply piping for a sink
Plastic pipe is in wide use for domestic water supply and drain-waste-vent (DWV) pipe. Principal types include: Polyvinyl chloride (PVC)
The method for producing cross-linked polyethylene (PEX) was also developed in the 1950 s. Plastic supply pipes have become increasingly common, with a variety of materials and fittings employed.
Rigid plastic pipes similar to PVC drain pipes but with thicker walls to deal with water pressure. PVC stands for polyvinyl chloride, and it has become a common replacement for metal piping. PVC should be used only for cold water, or for venting. CPVC can be used for hot and cold potable water supply.
The material is used primarily in food packaging, and clinical equipment, but since the early 1970 s has seen increasing use worldwide for both domestic hot and cold water. PP pipes are heat fused, being unsuitable for the use of glues, solvents, or mechanical fittings. PP pipe is often used in green building projects.
Flexible plastic pipe which is attached to barbed fittings and secured in place with a copper crimp ring. The primary manufacturer of PBT tubing and fittings was driven into bankruptcy by a class-action lawsuit over failures of this system. However, PB and PBT tubing has since returned to the market and codes, typically first for “exposed locations” such as risers.
Cross-linked polyethylene system with mechanically joined fittings employing barbs, and crimped steel or copper rings.
Plastic polyethylene cisterns, underground water tanks, above ground water tanks, are usually made of linear polyethylene suitable as a potable water storage tank.
Known as PEX-Al-PEX, for its PEX/aluminum sandwich, consisting of aluminum pipe sandwiched between layers of PEX, and connected with modified brass compression fittings.