Water supply systems, storage, pumping and plumbing fixtures
Water supply, storage, pumping and fixtures
This domain covers how water reaches a tap: source to sump, pump to overhead tank, gravity to fixtures, plus correct fixture selection and backflow protection.
System layout
- Direct system: municipal main feeds fixtures directly; pressure is unreliable.
- Indirect system: main fills an underground sump, a pump lifts to an overhead tank, and gravity distributes - the standard Indian arrangement.
- Storage sizing: domestic demand is taken as about 135 litres per capita per day; provide one to one-and-a-half days of storage.
- Tank height: keep roughly 1.5 to 3 m residual head at the topmost tap; higher buildings need a pressure-reducing valve on lower floors.
Pumping and controls
Fit a foot valve and strainer on the suction line, keep the suction pipe short and one size larger than the delivery, fit a non-return valve and gate valve on the delivery, and protect the pump with a dry-run cut-off. The tank needs an overflow, a float valve, a washout and a locked lid.
Fixtures
WC with 6/3 litre dual-flush cistern, wash basin, kitchen sink, bib cock, pillar cock, angle valve, health faucet, geyser with tempering valve. Every fixture connection needs an air gap or a backflow preventer.
Worked example
A family of 5 needs storage. Reasoning: 5 × 135 = 675 litres per day; for 1.5 days, 675 × 1.5 = 1012 litres, so specify a 1000 litre tank, placed so the topmost tap still gets about 2 m of head.
Traps that cost marks
No air gap or backflow protection; suction pipe smaller than delivery; pump without foot valve; tank without overflow or lid; forgetting that dead legs and long runs reduce pressure at the far tap.