How to Determine the Cost of Replacing Drain Pipes

Determine the diameter of the current drain pipes you're replacing. Measure the diameter of the inside of the pipe, not the outside. Measure the distance of pre-threaded piping from the inside edges of the threads, not the tip-to-tip length of the pipe. For non-threaded piping, measure from face to face, or desired length of the pipe when fitted into place. Allow extra measurements for the distance each end of a pipe fits into a socket or fitting.

Select the proper fittings for the repair job. Fittings come in 45- to 90-degree elbow angles as well as Ts, reducing couplings and bends, depending on the type of pipe you need. When selecting pipes and fittings, fit them together at the supply store and measure for accuracy. When working with PVC piping, purchase lengths slightly longer than needed, as you can always trim them down.

Determine what type of piping you need. Cost of replacement drain pipes also depend on the type of piping used. Copper, galvanized steel, threaded and non-threaded piping differ in cost. Plastic PVC or ABS piping is cheaper than cast iron. Determine which type of piping is best for your scenario before purchasing.

Determine costs for renting or purchasing tools or equipment for the repair job, which may also increase cost of plumbing repairs. Commonly used tools for plumbing repairs include wrenches, pliers, putty or sealants, hacksaws or pipe cutters, pipe threaders and others.

Get estimates for the repair job if you don't want to do it yourself. Cost of plumbing repairs also depends on whether you're doing the job yourself or hiring a plumber. Plumbers generally charge hourly rates. For example, a master plumber may charge up to $30 an hour, while a plumber may charge just under $20 an hour. Service fees to come to your location may cost between $25 and $75 or more, depending on your area and the plumbing service. Average cost of drain replacement plumbing is $400, according to A Plumbing.