I have took some water from the Contractor's purification plant and sent to reputable water testing laboratory.The tested parameters were pH,electrical conductivity,total dissolved solids,settable matter,turbidity,colour,phenohthalin alkalinity,total alkalinity,total hardness,corbonate hardness,non carbonate hardness,calcium,magnesium,sodium,potassium,iron,manganese,ammonical nitrogen,nitrite nitrogen,orthophosphate,sulphate,chloride,fluoride and permanganate value.The testing laboratory has already submitted the test results to me.But I don't have any literature to compare with the test results,literature which give the minimum and maximum requirements.If some one knows the literature which give the maximum and mimimum requirements can assist.

http://water.epa.gov/drink/contaminants/index.cfm

Orenda

standards vary by country. You might try the World Health Org (WHO). See link below for standards

http://www.who.int/water_sanitation_health/dwq/gdwq3rev/en/index.html