Water is the cheapest ingredient in concrete and the easiest to get wrong — too much of it in the mix, too little of it during curing, or the wrong kind entirely.
Quality
| Water | For concrete? |
|---|---|
| Municipal or drinking water | Yes |
| Clean borewell water | Usually yes; test if salty or hard |
| Water with visible oil, sewage or industrial waste | No |
| Seawater, brackish water | Not for RCC |
IS 456 sets limits on acidity, organic and inorganic solids, sulphates and chlorides, and allows doubtful water to be tested by comparing setting time and strength against distilled water.
Quantity
| Use | Approximate water |
|---|---|
| Mixing M20 concrete | 180 – 200 L per m³ |
| Mixing 1:6 mortar | Proportionate to cement, workable consistency |
| Pond fill on a slab (25–50 mm) | 25 – 50 L per m² |
| Daily curing top-ups | Much higher in March – June |
| Wetting blocks, walls, plaster | Ongoing |
A 1,000 sq ft (≈93 m²) slab pond 50 mm deep holds about 4,600 litres before evaporation — nearly a 5,000-litre tanker just to fill once.
Planning Supply
- Borewell drilled early, if the plan and permissions allow.
- Tankers booked around pour days and curing periods.
- Storage — a tank or the future sump, cleaned, to hold a day or two of water.
- Summer — budget for more top-ups.
The Short Version
Clean water for the mix, measured carefully; lots of water for curing, planned in advance. Test anything doubtful before it touches your steel.
