Question

If you were on the job site and the plumber was installing copper piping with a green color marking along its length, what could you infer from this color marking?

Answer

A green color marking would indicate that the plumber is using a type "K" copper tubing. Copper tubing for water piping comes in "K," "L," and "M" types, referring to the tubing thickness. Type "K," with its green marking, is the thickest. Type "L" has blue markings and is thinner, and type "M," with a red marking, is the thinnest. Copper tubing used for drainage, waste, or venting has a "DWV" designation.