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REHS Exam: Water Questions With
Complete Solutions
Water supply, water treatment, water standards, water contaminants, wells, surface water Around what percent of Earth's water is freshwater? correct answer: 1-3% What is the saturated zone? correct answer: Underground region in which all the earth's pores are filled with water What is the water table? correct answer: The level below which the ground is saturated with water What is the vadose zone? correct answer: The unsaturated area above the water table What is an artesian well? correct answer: A well drilled into an aquifer under pressure, requiring no pumping to get water flow What is an aquitard? correct answer: Usually a layer of clay, soil, silt, or sand that impedes the flow of water What does the Safe Drinking Water Act (SDWA) consider a Public Water System (PWS)? correct answer: Water system that has at least 15 connections OR regularly serves at least 25 people
What is the difference between a community water system (CWS) and non-community water system (NCWS)? correct answer: NCWSs do not serve a permanent resident population All wells EXCEPT this type of well are regulated by the EPA correct answer: Private wells Which of the following is true regarding slow sand filtration? a) Consists of small filter beds with fast filtration rates b) Consists of large filter beds with slow filtration rates c) Uses chemical coagulation d) Does not reduce bacteria correct answer: b) Consists of large filter beds with slow filtration rates In coagulation, finely dispersed solids (colloids), form large particles called _________ when an electrical charge is passed through the medium. correct answer: floc Larger flocs are removed by __________________ correct answer: sedimentation Quality of sanitary surveys is totally dependent on: correct answer: the quality of the surveyor The 1974 Safe Drinking Water Act allows the EPA to enforce regulations called: correct answer: the National Primary Drinking Water Regulations
What are the three main viruses of concern in water? correct answer: Rotavirus, Norwalk virus, and hepatitis A What kind of virus is the most common cause of sever diarrhea in children? correct answer: Rotavirus What is the reservoir for Norwalk virus? correct answer: Humans How can hepatitis A be transmitted? correct answer: Fecal-oral, person-to-person, contaminated food and water (esp. mollusks) What treatment option is the most effective for the treatment of viruses? correct answer: Ozone Pseudomonas aeruginosa is responsible for what common infection? correct answer: Swimmer's itch How is Legionella pneumophila transmitted? correct answer: Inhalation of contaminated aerosols (air-conditioning). No person-to-person transmission Typhoid fever (enteric fever) is caused by what bacteria? correct answer: Salmonella typhi What bacteria is the most common source of US bacterial diarrhea? correct answer: Campylobacter jejuni Shigella causes what infection? correct answer: Bacillary dysentery (shigellosis)
Cholera 01 or epidemic cholera is caused by what? correct answer: Vibrio cholera This bacteria can lead to HUS and kidney failure correct answer: E. Coli 0157:H What disease is caused by Giardia lamblia? correct answer: Beaver fever What is an effective way of removed Giardia from water? correct answer: One-micron filtration How is cryptosporidium transmitted? correct answer: - Contaminated food and water
- fecal-oral
- Oocysts resistant to chlorination Naegleria fowleri is also known as? correct answer: Brain eating amoeba Entamoeba histolytica is responsible for this disease correct answer: Amebic dysentery (amoebiasis) Cats/felines are common reservoirs for this waterborne protozoa. correct answer: Toxoplasma gondii How can Toxoplasma gondii be transmitted? correct answer: Undercooked contaminated meat, cross-contamination, accidental ingestion from litter boxes, congenial (mother to new born)
How long after collecting a sample of water should you wait to test for organisms? correct answer: 6-12 hours after What indicator indicates fresh pollution? correct answer: Fecal coliforms What indicator indicates previous pollution? correct answer: Clostridium perfringens What is commonly used to fill abandoned wells? correct answer: Cement, concrete, or bentonite What are possible contaminants in rainwater? correct answer: Roof dirt, air pollutants, cadmium, zinc Low dissolved oxygen is common in what kind of lake? correct answer: Eutrophic Young lakes with high dissolved oxygen with scant fish and plants are indicative of what kind of lake? correct answer: Oligotrophic Intermediate levels of nutrients, clarity, fish populations, and algae production are indicative of what kind of lake? correct answer: Mesotrophic Low DO, increased suspended solids, and bottom sludge is found in this zone of stream correct answer: Zone of degradation
DO near zero, no fish, and midge flies are indicative of what zone? correct answer: Zone of active decomposition Gradual reversal of pollution and increasing biodiversity and DO are indicative of what zone? correct answer: Zone of recovery What are sufactants? correct answer: Substance that reduces surface tension to allow grease and dirt to be washed away What are MBAS? correct answer: Methylene blue active substance: any compound that reacts with methylene blue
