1 / 20

Safety of potable water

Safety of potable water. FS0104 1. 2000. Demand for water. Some compelling statistics. human water use has increased more than 35-fold over the past three centuries.

earlmiller
Download Presentation

Safety of potable water

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Safetyofpotablewater FS0104 1 2000

  2. Demandforwater Some compelling statistics • human water use has increased more than 35-fold over the past three centuries • per capita water consumption in North and Central America is twice that of Europe, three times that of Asia and seven times that of Africa • about one billion people in developing countries do not have access to potable water • unsafe water, along with food, is implicated in 3 million deaths about 2.4 billion episodes of illness per year • the world's population, now 5 billion, is expected to increase to 8 billion by 2025 and 10 billion by 2050. This means that demands for water and food will also increase. FS0104 2 2000

  3. Watersafety amatterofpublicconcern Water quality ‹ strictly regulated ‹ an important public health indicator ‹ standards are becoming more rigorous FS0104 3 2000

  4. Hazardsinwater Surface water ‹acid rain ‹ storm water runoff ‹ pesticide runoff ‹ industrial waste FS0104 4 2000

  5. Hazardsinwater Ground Water ‹disease-producing pathogens ‹leachate from landfills and septic systems ‹ hazardous household products ‹ agricultural chemicals ‹ leaking underground storage tanks FS0104 5 2000

  6. Waterbornepathogens These organisms cause most waterborne infections ‹bacteria ‹ viruses ‹ parasites FS0104 6 2000

  7. Waterbornepathogens Bacteria • Shigella spp • Pathogenic Escherichia coli • Vibrio cholerae • Campylobacter jejuni • Salmonella typhi Viruses • Adenoviruses • Enteroviruses • Hepatitis A & E • Norwalk virus • Rota virus • Small round viruses Parasites • Giardia intestinalis • Cryptosporidium parvum • Entamoeba histolytica FS0104 7 2000

  8. Toxinsassociatedwith Cyanobacteria • hepatoxins (induce death by circulatory shock and liver haemorrhage) • neurotoxins • lipopolysaccharides FS0104 8 2000

  9. Othersourcesofcontamination indrinkingwater • corrosion or deposits on pipes and storage tanks, caused by iron and sulfur bacteria • colonisation by microorganisms of non-metallic pipe-fittings, joints, lining • microbial growth in distribution systems, encouraged by the presence of organic carbon in the water • infestation of water mains by animal life FS0104 9 2000

  10. Characteristicsof waterbornepathogens • ‹ pathogens are discrete and not in solution • ‹pathogens are often clumped, or adhere to solids in water; thus, the likelihood of acquiring an infective dose cannot be predicted from their concentration in water • ‹the likelihood that the pathogen will cause an infection dependson itsinvasiveness and virulence, and the immunity of the individual • ‹ pathogens multiply in their host FS0104 10 2000

  11. Categoriesofchemicalcontaminants indrinkingwater • toxic organic chemicals • toxic inorganic chemicals • radioactive elements. FS0104 11 2000

  12. Toxicorganicchemicals • Trihalomthanes (THMs) • Pesticides herbicides insecticides fungicides • Volatile organic chemicals (VOCs) FS0104 12 2000

  13. Toxicinorganicchemicals • arsenic • barium • Cadmium • Chromium • Lead • Mercury • nitrate • silver FS0104 13 2000

  14. Radiologicalaspectsof drinkingwaterquality • environmental radiation originates from natural and man-made sources • radionuclides occur naturally in drinking water • drinking water is not a significant source of exposure to radionuclides FS0104 14 2000

  15. Ensuringwaterquality Focus of water quality assurance programs ‹ selection and protection of sources ‹ treatment process ‹ distribution networks FS0104 15 2000

  16. Protectingwatersources -isolation or protection of the watershed - control of polluting activities in the area - protection of springs, wells and ground water - control or prevention of public access FS0104 16 2000

  17. Watertreatment Treatment of urban water ‹pre-disinfection ‹ coagulation, flocculation, sedimentation ‹ filtration ‹ disinfection FS0104 17 2000

  18. Controllingthedistribution system - deterioration of underground reservoirs - back siphonage of contaminated water, due to loss of pressure - microbial growth, especially on lining materials and plastics - corrosion of tanks, pipes, valves and pumps FS0104 18 2000

  19. Assuringdrinkingwatersafety: generalconsiderations -compliance with existing guidelines - monitoring to ensure continued compliance - having adequate contingency plans in place to be used in emergencies FS0104 19 2000

  20. Summary - Only a small percentage of the earth's water is available for drinking - Demand for safe water is increasing - Microbial contamination (by bacteria, viruses, parasites, algae) is the most serious problem - Tolerable Daily Intake levels (TDIs) have been established for chemical contaminants - Water quality assurance efforts should focus on: selection/protection of sources, treatment, distribution - Compliance with WHO guidelines on drinking water quality should assure a safe water supply FS0104 20 2000

More Related