What type of joints are prohibited for cement or concrete in water service piping?

The use of cement joints in water service piping is prohibited because cement does not provide the necessary flexibility and sealing properties required in water supply systems. Water service piping is often subject to movement due to thermal expansion and contraction, ground settling, and other environmental factors. Rigid joints, such as those made with cement, can crack or break under these conditions, leading to leaks and potential failures in the piping system.

Flexible joints, for example, allow for movement and can absorb stress without compromising the integrity of the joint, making them suitable for water service applications. Prohibited joints and concrete joints are not specified in this context as they generally do not refer directly to the function or specifications needed for water service piping compared to how cement joints fail to meet those critical requirements for durability and flexibility.