Water supply chain

Clean water at a tap is the end of a long chain. It starts with a source: a river, reservoir, lake or aquifer. Water is drawn through an intake, pumped or carried by gravity along a raw-water main, and treated at a water treatment plant. Treated water is pumped to service reservoirs, often overhead tanks, which balance demand through the day and keep pressure up. A network of mains and service pipes then delivers it to homes.

Each link is a civil engineering job: dams and intakes, large pipelines and their surge protection, treatment units, reservoirs and distribution networks. Design starts with demand, population times per-capita supply, projected thirty years ahead with allowances for losses and peaks.

Used water then enters the sanitation chain: drains, sewers, treatment and safe discharge or reuse. Keeping the two chains apart, with no leaks, cross-connections or back-flow, is the core of public health engineering.

In India, the CPHEEO manuals and IS 1172 guide planning, and IS 10500 sets drinking-water quality limits. Each area now has its own subject page in this library.