Contaminated water is a major hazard for the traveler, not only in developing countries but also in industrialized nations. A traveler requires a means of making water safe yet is compact enough to transport.
Water contaminants that can cause infection:
(1) viruses, including Hepatitis A, Poliovirus, Rotavirus, Norovirus
(2) bacteria, especially enteric bacteria such as E. coli, Vibrio and Shigella
(3) protozoa such as Giardia, Cryptosporidium and Isospora
(4) nematodes and trematodes
Other types of contaminants in water may include:
(1) salt
(2) chemicals including pesticides and toxins
(3) radon
Aesthetic problems with impure water:
(1) odor
(2) color
(3) turbidity
|
Treatment Method |
Effectiveness |
Problems |
|
macrofiltration or sedimentation |
removes debris and large parasites |
does not remove chemicals, viruses or bacteria |
|
coagulation-flocculation (alum, other) |
reduces contaminants |
does not disinfect |
|
microfiltration (ceramic, plastic membrane, other) with or without disinfectant |
removes bacteria and protozoa |
does not remove chemicals or viruses; filters may clog or harbor bacteria; damage to filter renders it ineffective |
|
filtration through activated charcoal |
removes chemicals; can reduce micro-organisms |
filter can become clogged; does not disinfect |
|
purifier (microfiltration or ultrafiltration plus a disinfectant) |
removes viruses as well as bacteria and protozoa |
does not remove chemicals; filters may clog or harbor bacteria; damage to filter renders it ineffective |
|
boiling |
kills micro-organisms if done properly |
does not remove chemicals; altitude affects the boiling temperature; requires fuel or electricity |
|
distillation |
distilled water is free of micro-organisms |
may not remove volatile chemical contaminants; may be bulky; requires fuel or electricity |
|
halogen (iodine, chlorine) |
effective in killing bacteria and protozoa; viruses require higher concentrations and longer contact times |
bad taste, which can be masked; does not remove chemicals; requires sufficient contact time to be effective; less effective in cold or if there is a lot of organic matter |
|
reverse osmosis |
removes all contaminants |
slow and expensive; units need careful cleaning |
|
batch process solar disinfection (SODIS); solar photocatalytic disinfection (SPCDIS) |
kills protozoa and their cysts |
requires sunlight; does not remove chemicals or viruses |
Several modalities may be combined into a treatment strategy.
(1) Pretreatment by filtration, coagulation-flocculation, and/or passage through activated charcoal can make subsequent steps more efficient.
(2) The choice of a method to remove protozoa and bacteria is based on preferences, resources and time constraints.
(3) The need to remove viruses may require more aggressive water treatment.
Treated water must be handled properly or it will become contaminated. It should be kept in a clean, closed water container. Access to the water should minimize introduction of foreign matter.
Specialty: Infectious Diseases
ICD-10: ,
