As per IS456:2000

Cl. 5.4, Page No. 14, Potable water is generally considered satisfactory for mixing concrete.

Cl. 5.4.1.2, Page No. 14, Compressive strength of atleast 3 concrete cubes prepared with proposed water shall not be less than 90% of average compressive strength of cubes prepared with distilled water.

Cl. 5.4.1.3, Page No. 14, Initial setting time shall not vary by +/- 30 minutes when compared with proposed water and distilled water using same cement.

Cl. 5.4.2, Page No. 14, pH of the water shall not be less than 6.

Cl. 5.4.3, Page No. 14, Sea water is not suitable because of presence of harmful chemicals