As water moves through the water cycle, it naturally picks up many things along its path. Water quality will naturally change from place to place, with the seasons, and with the kinds of rocks and soil which it moves through. Water can also be polluted by human activities, such as open defecation, inadequate wastewater management, dumping of garbage, poor agricultural practices (e.g., use of fertilizers or pesticides near water sources), and chemical spills at industrial sites. Even though water may be clear, it does not necessarily mean that it is safe for us to drink. It is important to judge the safety of water by taking the following three types of parameters into consideration:

ü  Microbiological quality is usually the main concern since infectious diseases caused by pathogenic bacteria, viruses, protozoa and helminths are the most common and widespread health risk associated with drinking water.

ü  Chemical parameter: minerals, heavy metals like arsenic, chemicals and pH

ü  Physical parameter: temperature, color, smell, taste and turbidity

Safe drinking water should have the following microbiological, chemical and physical parameters:

·   Free of pathogens (A pathogen is any living organism that causes disease. Pathogens commonly found in drinking water include bacteria, viruses, protozoa and helminths)

·    Low in concentrations of toxic chemicals

·   Clear

·    Tasteless, odorless and colorless (for aesthetic purposes)

References

1. World Health Organization (2011). Guidelines for Drinking-Water Quality: Second Addendum. Vol. 1, Recommendations, Third Edition. WHO, Geneva, Switzerland.

2.  UNICEF (2010). Technical Bulletin No.6, Water Quality Assessment and Monitoring. UNICEF, Supply Division, Copenhagen, Denmark.

3.  World Health Organization and UNICEF (2013). Progress on Sanitation and Drinking-Water:2013 Update. WHO, Geneva, Switzerland.