Which type of plastic pipe is approved for acid waste, both underground and above ground?

The correct answer is that all of the mentioned types of plastic pipe — PVC, Polypropylene, and CPVC — are approved for handling acid waste, both underground and above ground. Each type offers specific advantages that make them suitable for this application.

PVC (Polyvinyl Chloride) is commonly used in a variety of plumbing applications, including waste and vent systems. While it is resistant to many chemicals, its ability to handle acidic environments can be limited compared to other materials.

Polypropylene is particularly well-regarded for its high chemical resistance, making it an excellent choice for acid waste systems. Its robust nature allows it to withstand the corrosive effects of certain acids, ensuring a longer lifespan when used in applications involving hazardous materials.

CPVC (Chlorinated Polyvinyl Chloride) is also suitable for acid waste applications due to its superior resistance to heat and corrosive substances compared to standard PVC. It is often used in situations where higher temperatures and chemical resistance are necessary.

Given the favorable properties of all three options, they can be utilized for acid waste systems, both underground and above ground, making the collective answer correct. This option acknowledges the versatility and applicability of these materials in handling corrosive substances in plumbing systems.