Tulane Module 4 (Potable Water)

What is TRUE about Ct values that indicate the concentration and time conditions theoretically required to achieve a particular log reduction of a microorganism at a particular temperature? A. Ct is the product of disinfectant concentration in mg/L and contact time in minutes at a particular temperature B. the higher the Ct, the better for selecting a disinfectant and conditions C. Cts increase as water temperature increases D. all of the above

A. Ct is the product of disinfectant concentration in mg/L and contact time in minutes at a particular temperature

Why is conventional water treatment usually required for surface source waters? A. it reduces particulates, turbidity, and microbial contamination B. it effectively removes SOCs and VOCs C. it is cheaper than disinfection D. all of the above

A. it reduces particulates, turbidity, and microbial contamination

Which of the following is TRUE about waterborne disease occurrence? (choose all that apply) A. the risk of waterborne disease outbreaks seems to be reduced over the last many years in the US B. untreated contaminated groundwater and distribution system problems have been the most frequent causes of waterborne disease outbreaks C. waterborne disease outbreaks are readily detected when they occur

A. the risk of waterborne disease outbreaks seems to be reduced over the last many years in the US B. untreated contaminated groundwater and distribution system problems have been the most frequent causes of waterborne disease outbreaks

For which of the following microorganisms is chlorine a good disinfectant? A. bacteria, viruses, cryptosporidium B. bacteria, viruses C. bacteria and cryptosporidium D. viruses and cryptosporidium

B. bacteria, viruses

Which of the following is TRUE about total coliforms and E. coli? A. detection of total coliforms probably indicates contamination from sewage B. detection of E. coli probably indicates contamination from sewage C. a verified positive total coliform with no E. coli should result in a boil water notice D. zero total coliforms in 100 ml of drinking water is a good indication for the presence of Cryptosporidium parvum

B. detection of E. coli probably indicates contamination from sewage

Which of the following is TRUE about the potential consequences of minor exposures above a chemical MCL? A. it requires that the water supply be put on a boil order B. it is not usually a significant risk because MCLs usually have large margins of safety C. it always requires the installation of treatment technology D. it requires immediate public notification

B. it is not usually a significant risk because MCLs usually have large margins of safety

What are states NOT permitted to do with respect to safe drinking water regulation? A. produce regulations that are more stringent than EPA guidelines B. produce regulations that are less stringent than EPA guidelines C. require water suppliers to monitor for additional contaminants D. bring enforcement actions against violators of MCLs

B. produce regulations that are less stringent than EPA guidelines

What is the most appropriate use of chloramines in water? A. primary disinfectants B. secondary disinfectants and depressants of by-product formation C. primary and secondary disinfectants D. none of the above

B. secondary disinfectants and depressants of by-product formation

Which of the following is TRUE about source water protection programs? (choose all that apply) A. They are not important because water treatment can deal with any contamination issues B. they reduce risks and costs for water suppliers C. they are an important part of the multiple barrier system

B. they reduce risks and costs for water suppliers C. they are an important part of the multiple barrier system

Which of the following is correct regarding the Lead and Copper Rule? A. lead and copper are common source water contaminants B. the MCL for lead is 0.015 mg/L C. lead sampling is done in the home on 1 liter first draw water samples that have been stagnant for at least 6 hours in the pipe D. lead and copper are treated by coagulation

C. lead sampling is done in the home on 1 liter first draw water samples that have been stagnant for at least 6 hours in the pipe

Which statement is correct regarding Drinking Water supplies? A. they are a significant contributor to cancer risks in the population due to disinfection by-products B. they should be disinfected to become sterile so that no bacteria are present in the water C. they always have the potential risk of microbial contamination that must be managed and prevented D. they should be retreated in the home with point-of-use or point-of-entry systems

C. they always have the potential risk of microbial contamination that must be managed and prevented

What is the primary purpose of a residual disinfectant in the water distribution system? A. to kill pathogens that were not removed by the primary treatment in the plant B. to prevent disease outbreaks caused by cross connections C. to reduce growth of biofilms and normally nonpathogenic microorganisms D. to kill cryptosporidium that are not filtered in the treatment plant

C. to reduce growth of biofilms and normally nonpathogenic microorganisms

Which of the following are correct statements about risk considerations in drinking water regulations development? A. most chemicals have MCLGs calculated from No Observed Adverse Effects Levels (NOAELs) and include safety (uncertainty) factors B. genotoxic chemicals have MCLGs of zero, and hypothetical cancer risk levels are calculated from mathematical models C. MCLs are set as close to the MCLG as technically and economically feasible D. all of the above

D. all of the above

Which of the following are present in Safe Drinking Water Act (SDWA) regulations? A. many MCLs and MCLGs for microbials and chemical contaminants B. treatment requirements for several microbials C. monitoring and reporting requirements D. all of the above

D. all of the above

Which of the following is TRUE about excess nitrates and/or nitrites in drinking water? A. nitrates and nitrites are often caused by sewage or fertilizer contamination B. nitrates and nitrites are water soluble and will move through soils to contaminate groundwater C. infants 3 to 6 months old are at risk to methemoglobinemia from high nitrate or nitrite levels, especially if the water is also microbially contaminated D. all of the above

D. all of the above

Which of the following is TRUE about regulations under the Safe Drinking Water Act? A. MCLs are legally enforceable drinking water standards B. MCLGs are health goals but not enforceable standards C. even though MCL could be higher than MCLG, it is still a 'safe' standard D. all of the above

D. all of the above

Which of the following is true about ground waters? A. they are often safe to use without disinfection B. they are sometimes contaminated by natural contaminants like arsenic and can be contaminated by septic tank and surface contaminants C. they are usually microbiologically safe if not Ground Water Under the Direct Influence of Surface Water (GWUDI) D. all of the above

D. all of the above

Why are indicator organisms rather than individual pathogens usually used as standards for water quality management? A. indicators are easier and less expensive to monitor water quality B. it would be necessary to monitor for dozens of individual pathogens C. it is generally not necessary to know which specific pathogens might be present in the source water, but just that they are being controlled D. all of the above

D. all of the above

Why must almost all surface waters and Ground Waters Under the Direct Influence of Surface Waters be evaluated and treated in some way for cryptosporidium parvum? A. cryptosporidium parvum oocysts are common in source waters and especially those impacted by upstream sewage discharges B. cryptosporidium parvum oocysts are not affected by chlorination C. cryptosporidium parvum oocysts are difficult to filter out because they are very small D. all of the above

D. all of the above

Why should all water supplies have periodic sanitary surveys? A. sanitary surveys can identify potential problems and help prevent quality and compliance problems B. sanitary surveys are a good way to become familiar with water suppliers and operators and to assist them C. sanitary surveys are a teaching tool that helps water suppliers understand their system and do a better job D. all of the above

D. all of the above