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 natural water can have certain effects 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. We will talk about them in this article.

Drinking water standards

Table of Contents

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 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, 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 sulphates are highly soluble in water. So even after water treatment, they may still be present in the water. Although it is harmless at a moderate level, if its concentration exceeds 500 ppm in water, it can cause dehydration, diarrhoea, 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, aluminium, 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 Organization (WHO).

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

Organic species:
  • Carbon tetrachloride
  • 1,2-Dichlorobenzene
  • 1,4-Dichlorobenzene
  • 1,2-Dichloroethane
  • 1,2-Dichloroethene
  • Dichloromethane
  • Bis(2-ethylhexyl)phthalate
8 μg/l
  • 1,4-Dioxane
  • Edetic acid
  • Ethylbenzene
300 μg/l
  • Hexachlorobutadiene
0.6 μg/l
  • Nitrilotriacetic acid
  • Pentachlorophenol
  • Styrene
  • Tetrachloroethene
  • Trichloroethene
  • Xylenes

Frequently Asked Questions – FAQs


What should be the quality of drinking water?

Also, extremely important is the aesthetic quality of the drinking water. Public health turbidity requirements lead in most cases to clear, attractive water. High concentrations of dissolved solids, though safe, produce water with a slightly alkaline taste.


What is the best pH water to drink?

The pH level of the water sources should be between 6.5 and 8.5 on a scale ranging from 0 to 14. The best pH for drinking water sits at a 7 right in the middle.


Which is the most commonly found chemical in water?

The most common chlorine, by far. Chlorine kills many organisms that can cause ailments and diseases. There is little chance of dangerous outbreaks like dysentery, by adding chlorine to the water supply.


What is the most common contaminant in drinking water?

Microorganisms, nitrate, and arsenic are the most common contaminants in drinking water. Over the last five years, monitoring of water quality has improved. Bacteria, viruses, and protozoa are contaminants of drinking water which can quickly cause widespread and serious diseases.


What is the most dangerous water contaminant?

Lead is one of the most dangerous elements found in drinking water, for young people and infants in particular. Contamination can occur from natural deposits in the water supply, but is most likely the result of the leaching of pipes inside a house or flat building.

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