Water pollution and fecal-oral route

Water pollution is any change in the physical, chemical or biological quality of water that makes it harmful to health or unfit for use. It is caused by adding substances such as sewage, industrial chemicals, fertilisers, pesticides, pathogens or heat beyond the self-purifying capacity of the water body.

Types of water pollution

• Physical – turbidity, colour, odour, temperature (thermal pollution).
• Chemical – organic (BOD-causing matter) and inorganic (arsenic, iron, nitrate, heavy metals).
• Biological – pathogens: bacteria, viruses, protozoa, worm eggs.

Sources and causes

• Untreated domestic sewage (e.g. Bagmati and Bishnumati in Kathmandu).
• Industrial effluent (tanneries, dyeing, distilleries).
• Agricultural runoff with fertilisers and pesticides.
• Solid waste dumping on river banks.
• Open defecation and leaking septic tanks.
• Natural arsenic in Terai groundwater.

Effects

• Water-borne diseases (cholera, typhoid, diarrhoea, hepatitis).
• Arsenicosis, nitrate poisoning.
• Oxygen depletion, fish kill, eutrophication.
• Loss of aesthetic, religious and recreational value; higher treatment cost.

Fecal-oral infection route

Pathogens in faeces of an infected person reach the mouth of another through the "F-diagram":

             +--> Fluids (water) ------+
             +--> Fingers -------------+
 FAECES -----+--> Flies ---------------+--> FOOD --> MOUTH
             +--> Fields/soil ---------+

• Fluids: polluted water from sewage-contaminated sources or pipes.
• Fingers: unwashed hands after defecation.
• Flies: carry faecal matter to food.
• Fields: open defecation, raw excreta on crops, contaminated soil.
• Food: contaminated by the above and eaten.

Mitigation measures

1. Safe excreta disposal – toilets for all households, end open defecation, safe faecal sludge management.
2. Safe water – protect sources, treat water (boiling, filtration, chlorination, SODIS), maintain pipelines, separate water and sewer lines.
3. Hand washing with soap at critical times.
4. Food hygiene – wash, cook and cover food.
5. Fly control – solid waste management and clean surroundings.
6. Sewage and industrial effluent treatment before discharge.
7. Health education and community participation.
8. Vaccination, deworming, and ORS for diarrhoea.