Water stagnation

Water stagnation or still water occurs when water stops flowing for a long period of time. Stagnant water can be a significant environmental hazard.^[1]

Dangers

Man drinking stagnant water in Chad

Malaria and dengue are among the main dangers of still water, which can become a breeding ground for the mosquitoes that transmit these diseases.^[2]

Stagnant water can be dangerous because it provides a better incubator than running water for many kinds of infectious pathogens. Stagnant water can be contaminated with human and animal feces, particularly in deserts or other areas of low rainfall.^[2] Water stagnation for as little as six days can completely change bacterial community composition and increase cell count.^[3]

Stagnant water may be classified into the following basic, although overlapping, types:

Water body stagnation (stagnation in swamp, lake, lagoon, river, etc.)
Surface and ground waters stagnation
Trapped water stagnation. The water may be trapped in human artifacts (discarded cans, plant pots, tires, dug-outs, roofs, etc.), as well as in natural containers, such as hollow tree trunks, leaf sheath, etc.

To avoid ground and surface water stagnation, drainage of surface and subsoil is advised. Areas with a shallow water table are more susceptible to ground water stagnation due to the lower availability of natural soil drainage.

Life that may thrive in stagnant water

Some plants prefer flowing water, while others, such as lotuses, prefer stagnant water.

Various anaerobic bacteria are commonly found in stagnant water.^[4] For this reason, pools of stagnant water have historically been used in processing hemp and some other fiber crops, as well as linden bark used for making bast shoes. Several weeks of soaking makes bast fibers easily separable due to bacterial and fermentative processes known as retting.

Denitrifying bacteria
Leptospira
Purple bacteria (both sulfur and non-sulfur)
Brain-eating amoeba

Fish

Insects

Stagnant water is the favorite breeding ground for a number of insects.

Dragonfly nymphs
Fly maggots
Mosquito larvae
Nepidae (water scorpions)

Other

Algae
Biofilm
A number of species of frogs prefer stagnant water.
Some species of turtles
- Mata mata

References

^ "General Article: Yellow Fever and Malaria in the Canal". Panama Canal (film). American Experience. Boston, MA: WGBH Educational Foundation. 2010. Archived from the original on Nov 29, 2016.
^ ^a ^b Health Risks Associated with Stagnant Water (PDF) (Report). Recommendations for Occupational Health and Safety Following Disasters. World Health Organization. 2013. Archived from the original (PDF) on November 27, 2014.
^ Ling, Fangqiong; Whitaker, Rachel; LeChevallier, Mark W.; Liu, Wen-Tso (1 June 2018). "Drinking water microbiome assembly induced by water stagnation". The ISME Journal. 12 (6): 1520–1531. Bibcode:2018ISMEJ..12.1520L. doi:10.1038/s41396-018-0101-5. ISSN 1751-7362. PMC 5955952. PMID 29588495.
^ Cabral, João (October 10, 2010). "Water Microbiology. Bacterial Pathogens and Water". International Journal of Environmental Research and Public Health. 7 (10): 3657–703. doi:10.3390/ijerph7103657. PMC 2996186. PMID 21139855.

[1] "General Article: Yellow Fever and Malaria in the Canal". Panama Canal (film). American Experience. Boston, MA: WGBH Educational Foundation. 2010. Archived from the original on Nov 29, 2016.

[WHO_health_risks-2] Health Risks Associated with Stagnant Water (PDF) (Report). Recommendations for Occupational Health and Safety Following Disasters. World Health Organization. 2013. Archived from the original (PDF) on November 27, 2014.

[3] Ling, Fangqiong; Whitaker, Rachel; LeChevallier, Mark W.; Liu, Wen-Tso (1 June 2018). "Drinking water microbiome assembly induced by water stagnation". The ISME Journal. 12 (6): 1520–1531. Bibcode:2018ISMEJ..12.1520L. doi:10.1038/s41396-018-0101-5. ISSN 1751-7362. PMC 5955952. PMID 29588495.

[4] Cabral, João (October 10, 2010). "Water Microbiology. Bacterial Pathogens and Water". International Journal of Environmental Research and Public Health. 7 (10): 3657–703. doi:10.3390/ijerph7103657. PMC 2996186. PMID 21139855.

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