A study has warned that cloudy drinking water is linked to increased cases of gastrointestinal illness. Cloudiness in water is caused by material floating in it. The undissolved particles may actually provide some protection for harmful pathogens against disinfectants.
Researcher Anneclaire De Roos from Drexel University in Philadelphia, US found associations between acute gastrointestinal illness (AGI) and water turbidity, a term meaning cloudiness or opacity. Turbidity is the cloudiness or haziness of a fluid caused by large numbers of individual particles that are generally invisible to the naked eye, similar to smoke in air.
The results revealed that exposures through drinking water caused a low but detectable number of AGI cases in the regions. There is no clear, alternative explanation for the patterns of associations — particularly when a similar pattern was seen multiple times. Acute gastrointestinal illness could be caused by waterborne pathogens like norovirus, Giardia, or Cryptosporidium and carry symptoms like diarrhoea and vomiting. Researchers looked into a collection of studies that had been done on the topic.
These studies were designed to evaluate risks from contamination of source waters (usually rivers in the cities studied), before the water entered cities’ distribution systems. They found that turbidity of drinking water was linked to increased AGI in multiple studies, and not just when there was increased cloudiness. “As expected, the association between turbidity and AGI was found in cities with relatively high turbidity levels, often in unfiltered drinking water supplies,” De Roos noted.