Design of plumbing systems.

A plumbing system is a long-term investment and should be so designed that it does not become outdated and need replacement while its major parts are still serviceable. This requires careful estimation of current and future demand so that the correct capacity can be specified.

The capacity and dimensions of component parts in a plumbing installation should be adequate to meet both immediate needs and anticipated future use. However, perfection in design is frequently compromised by cost, especially in poor and developing communities. Good design of plumbing systems is an important step in ensuring that the installations are efficient, safe and affordable. It should take into account the special needs and limitations of developing countries and should also ensure that the installations are appropriate for the different situations they serve. An understanding of the technical requirements and regulatory restrictions is vital for the provision of good plumbing services. This chapter includes design recommendations for plumbing installations in single dwellings, multiple dwellings and multi-storey buildings. It deals with special issues related to industrial and other special purposes, hot water and other dual supply systems and storm water drainage. It includes guidelines on capacities of plumbing systems, plumbing materials and products, and the use of protective devices to prevent back-siphonage and backflow.