Which type of pipe is least commonly used for hot and cold water applications?

Stainless steel pipes are less commonly used for hot and cold water applications when compared to other materials. While stainless steel is highly corrosion-resistant and has a high strength-to-weight ratio, which makes it an excellent choice for certain industrial applications and specialized use cases, its cost and applicability in residential or standard plumbing contexts limit its prevalence.

Other materials such as galvanized steel, copper, and various types of plastic are more commonly utilized in hot and cold water supply systems because they can be more cost-effective, easier to install, and suitable for a broader range of installations. For instance, copper pipes are favored for their antimicrobial properties and reliability, while plastic pipes are often chosen for their lightweight nature and resistance to corrosion.