Drinking Water Standards

There was a time when the common and safe sources of drinking water were the local wells and ponds. With the advancement in technology and increase in population, the water bodies have become polluted to the extent that they are not entirely safe even for washing purposes!

Considering the detrimental effects the natural water can have on human health, certain parameters have been defined by several health organizations. Some quality parameters are set for drinking water which must be met as per the International Standards for drinking water.

International Standards for Drinking Water

The International Standards for drinking water which must be followed are:

• Fluoride: Deficiency of fluoride causes tooth decay in humans. Water fluoridation is a method which ensures controlled the addition of soluble fluoride to the drinking water supply to bring its concentration up to 1 ppm. However, excess fluoride causes mottling of teeth and bone defects; so it is added only up to the safety limits.

• Lead: The water supply pipes, plumbing fittings, solders, etc. either contain lead or are made up of it. Excess lead has certain neurological effects. Long-term exposure can create health risks for pregnant women and infants. It can also damage the liver, kidney, etc. Thus, the permissible limit for lead concentration is 50 ppb only.

• Sulphate: Sulphate is often used for the control of algae in public water supply pipes. They are also discharged from mines into the water. Some of the sulphates are highly soluble in water. So even after water treatment, they may still be present in water. Although it is harmless at a moderate level, if its concentration exceeds 500 ppm in water, it can cause dehydration, diarrhea, certain laxative effects and gastrointestinal problems.

• Nitrate: Nitrates are used in fertilizers. They can reach surface and groundwater from agricultural fields. If the concentration of nitrates exceeds 50 ppm in water, the digestive system is affected. It also causes methemoglobinemia, commonly called the blue baby syndrome.

• Other metals: There are some other metals such as iron, copper, aluminum, zinc, etc., which have the permissible concentration of 0.2 ppm, 3 ppm, 0.2 ppm and 5 ppm respectively.

The following table contains the Drinking Water Standards issued by the World Health Organisation (WHO).

Drinking Water Standards by the WHO (Substance/ Parametric Value)