Competent design of PLUMBING systems is to prevent conflicts with other trades, and to avoid expensive rework or surplus supplies. The scope of standard residential plumbing usually covers mains pressure potable water, heated water (in conjunction with mechanical and/or electrical engineers), sewerage, storm water, natural gas, and sometimes rainwater collection and storage. In commercial environments, these distribution systems expand to accommodate many more users, as well as the addition of other plumbing services such as hydroponics, irrigation, fuels, oxygen, vacuum/compressed air, solids transfer, and more.

Plumbing systems also service air distribution/control, and contribute to the mechanical part of MEP. Plumbing for HVAC systems involves the transfer of coolant, pressurised air, water, and other substances. Ducting for air transfer may also be consider plumbing, but is generally installed by different tradespeople.