Although 71% of the Earth's surface is covered by water; 96.5% of such is oceanic water, leaving only 3.5% fresh water. 68.5% of that fresh water is within polar ice caps, glaciers and permanent snow. The remainder of fresh water resources are in the form of ground water, pallustrine water (swamp), riverine water (rivers), lacustrine water (lakes), atmospheric moisture and soil moisture.

Lake Baikal in Eastern Siberia, Russia contains 20% of the earth's non-frozen fresh water. Baikal is the world's oldest lake ast 25 million years and the world's deepest lake at 1,700 meters. Lake Baikal is also home to the world's only fresh water chemosynthetic benthic community and the only fresh water seal species - Nerpa (Pusa Siberica). Despite its apparent importance and value to humanity, Baikal is threatened:

• "A tourist boom, growing pollution and lack of sewage treatment has led to the disappearance of local fish species and a growth of putrid algae in Lake Baikal."The Guardian Oct. 19, 2017 "World's deepest lake crippled by putrid algae, poaching and pollution." Agence France-Presse Oct. 19, 2017
• "Hydroelectric dam project of Mongolian power companies, assisted by the World Bank which would imperil Lake Baikal by installing dams on the Selenga River, which flows into Lake Baikal."[Kenneth Rapoza in the April 7, 2017 edition of Forbes]

"Russian Authorities Investigating Mass Seal Deaths in Lake Baikal!" Moscow Times -- Oct. 31, 2017. 132 Seal (Nerpa -- Pusa Siberica) Carcasses Washed Ashore - at 3 locations along Lake Baikal.

The scarcity of potable water is exacerbated by drought, desertification as well as by threats posed by water-borne diseases. Particularly within certain developing countries, where poverty and armed conflict combine to wreak havoc on vulnerable communities, water-borne diseases have become endemic. The following represent a non-exhaustive set of examples:

Schitosomiasis [Schistosoma mansonii, S. haematobium, S. japonicum, S. intercolatum] Suzy J. Campbell, J. Russell Stothard Email author, Faye O'Halloran, Deborah Sankey, Timothy Durant, Dieudonné Eloundou Ombede, Gwladys Djomkam Chuinteu, Bonnie L. Webster, Lucas Cunningham, E. James LaCourse and Louis-Albert Tchuem-Tchuenté. "Urogenital schistosomiasis and soil-transmitted helminthiasis (STH) in Cameroon: An epidemiological update at Barombi Mbo and Barombi Kotto crater lakes assessing prospects for intensified control interventions," Infectious Diseases of Poverty 2017 6:49

https://doi.org/10.1186/s40249-017-0264-8

Cholera _(Vibrio cholerae) _Outbreak in Yemen 2017 (Source: Reliefweb.int)

"Adaptation of a simple dipstick test for detection of Vibrio cholerae O1 and O139 in environmental water." Subhra Chakraborty,1 Munirul Alam,2 Heather M. Scobie,1,† and David A. Frontiers in Microbiology. 29 October 2013 https://www.frontiersin.org/articles/10.3389/fmicb.2013.00320/full

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Giardia: Giardiasis https://medicineplus.gov/giardianinfections.html 2017. College of Idaho and Boise State U. researchers receive $418,000 NIH grant for Giardia recovery October 4, 2017.

Water-borne diseases are certainly not confined to developing countries, as exemplified by the following:

Naeglaria fowleri: "Brain eating amoeba found in two Louisiana water systems" by Morgan Winsor. June 30, 2017, 11:44 AM ET ABC News. http://abcnews.go.com/Health/brain-eating-amoeba-found-louisiana-water-systems/story?id=48372045

Necrotizing Faciitis: "Flesh-eating bacteria claim 2nd life after Hurricane Harvey" By M.L. NESTEL. Oct 25, 2017, 3:53 PM ET ABC NEWS.

New mom who lost limbs to flesh-eating bacteria sues hospital USA TODAY NETWORK Brett Molina, USA TODAY Published 11:18 a.m. ET Oct. 16, 2017

Shigella (Shigellosis): Shigella outbreak sickens dozens of students at Argentina school by NEWS DESK November 3, 2017.

Highly infectious vomiting bug is taking the United Kingdom by storm. Shigellosis swept the nation in February, and appears to be doing the rounds again By Ben Waldron Burton Mail Oct. 19, 2017 https://www.burtonmail.co.uk/news/health/highly-infectious-vomiting-bug-taking-583100

Leptospirosis (Leptospira): PUERTO RICO SEES RISE IN LEPTOSPIROSIS AFTER HURRICANE MARIA. "The strongest storm to hit the island in decades left hospitals flooded, strewn with rubble and dependent on diesel generators to keep the neediest patients alive." EYE WITNESS NEWS, 2017. http://ewn.co.za/2017/10/25/puerto-rico-sees-rise-in-leptospirosis-after-hurricane-maria.

Hotspots of Canine Leptospirasis in the USA:

Cryptospiridiosis: Crypto detected four times in a week. Jim Redden Monday, October 30, 2017 PORTLAND TRIBUNE. "Portland officials say Bull Run water is safe to drink but advise those with compromised immune systems to consult their doctors."

Legionnaires Disease (Legionella): Deadly legionella bacteria found in Perth Children's Hospital ...ABC Online-Nov 3, 2017

A new problem has struck the trouble-plagued Perth Children's Hospital with the potentially deadly legionella bacteria detected during routine ...

Deadly bug found at Perth Children's Hospital. Perth Now-Nov 3, 2017

Polio (Poliomyelitis): Webcast: Can The World Finally Wipe Out Polio?

October 20, 2017 6:00 AM ET NPR.

Centers for Disease Control (CDC) What is Polio? https://www.cdc.gov/polio/about/

Source: Polioeradication.org