What Is the Difference Between Type M & L Copper Pipe? | Hunker
Type K is green, type L is blue, type M is red and DWV is yellow. Type L pipe may be referred to as blue, type M is often referred to as red. Uses of Copper Pipe Types All the pipe types are suitable for use as plumbing, but DWV may not be used for water supply pipe since it has no pressure rating.