Water used to mix concrete is checked for the impurities that attack reinforcement or interfere with setting — chloride, sulphate, organic matter and suspended solids. Boiler feed water is checked for the impurities that cause scale, corrosion and carryover. Both are suitability tests, not safety tests.
Permissible limits for water used in mixing and curing plain and reinforced concrete under IS 456. Boiler feed water is assessed separately against the boiler manufacturer’s water chemistry specification.
| Parameter | Unit | Permissible limit | Why |
|---|---|---|---|
| pH value | — | Not less than 6 | Acidic water attacks cement paste |
| Organic matter | mg/L | 200 max | Interferes with setting and strength gain |
| Inorganic matter | mg/L | 3000 max | Total impurity load |
| Sulphates (as SO₃) | mg/L | 400 max | Sulphate attack on hardened concrete |
| Chlorides (as Cl) — reinforced concrete | mg/L | 500 max | Corrodes reinforcement steel |
| Chlorides (as Cl) — plain concrete | mg/L | 2000 max | No steel to protect, so relaxed |
| Suspended matter | mg/L | 2000 max | Affects water-cement ratio control |
Site water is often drawn from a borewell sunk for the project, and in parts of coastal and South Bengal that water can carry chloride well above the reinforced-concrete limit. Chloride-driven corrosion does not show up for years, and by then the remedy is structural. A single test before the first major pour is the cheapest risk control on the job.
Often yes, but it has to be tested first — particularly for chloride and sulphate. Proximity to the coast or to saline aquifers is the main risk factor, and it is not something you can judge by taste or appearance.
Not for reinforced concrete. The chloride content is far above the IS 456 limit and will corrode reinforcement. It is sometimes tolerated in unreinforced mass concrete, but that is a design decision, not a testing one.
Typically hardness, alkalinity, silica, chloride, dissolved oxygen indicators, TDS and conductivity — assessed against the pressure rating and the manufacturer’s specification, since a high-pressure boiler tolerates far less than a low-pressure one.
Find out how hard your water is: useful before buying a softener and for boiler or geyser scaling problems.
Lab note: Drop-count titration kit; follow the drop counts carefully.
Check price on AmazonPocket TDS tester with a wide range, useful for comparing raw water, RO output and reject water.
Lab note: Calibrate as per the manual; readings drift if the probe is not rinsed.
Check price on AmazonLow-cost dip-and-read pH check for drinking water, pool water and soil.
Lab note: Colour matching gives an approximate value, not a decimal reading.
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