REHS Studying (2020)

Drinking water standards generally specify that a water is safe provided that testing in a specified manner does not reveal more than an average of:

1 positive sample out of 40 samples taken

When using presettling reservoirs to eliminate heavy turbidity or pollution before treatment, what is the desirable retention time?

2 to 3 days

It is estimated that installation of water-saving plumbing devices in homes would save approximately:

55 gallons of water per day per 2-3 person household

What chemical is the most widely used to destroy microorganisms in water supplies?

Chlorine

The presence of what in water would indicate past or possibly intermittent pollution?

Clostridium perfringens

What organism is most resistant to unfavorable environmental conditions and indicates past or possibly present intermittent pollution?

Clostridium sporulates

The presence of what is most easily identified by lab analysis in water contaminated by feces?

Coliform

Which bacterial group is indicative of fecal contamination or sewage pollution?

Coliform

What testing method determines free available chlorine with minimal interference from combined chlorine, iron, nitrates, and nitrites?

DPD-colorimetric method

Degradation of groundwater supplied by human-generated pollutants is generally the result of:

Faulty water disposal practices

The presence of bacteria responsible for typhoid fever in a public water supply could be traced to what type of contamination?

Fecal

What soil condition is most favorable for removal of viruses?

Fine loamy sand over course sand and gravel

Granular activated carbon (GAC) filters are used to:

Treat water for soft drinks and bottled drinking water, remove taste and odor producing compounds, and remove synthetic organic chemicals (suspected carcinogens).

Any time a MCL is exceeded the NTNCWS must give notice by continuous posting in a conspicuous location within the area served by the water system. a. True b. False

a. True

Facultative bacteria live in either aerobic or anaerobic conditions. a. true b. false

a. true

The Maximum Contaminant Level (MCL) is the highest concentration of a contaminent that is allowable in a water system. a. true b. false

a. true

Viral hepatitis B (HBV) is most associated with:

administration of blood products

The liquid form of chlorine used for emergency disinfection of small volumes of a. calcium hypochlorite b. sodium hypochlorite c. bromide hypochlorite d. potassium hypochlorite

b. sodium hypochlorite

When collecting bacteriological samples that have been chlorinated, what chemical is used to dechlorinate the water? a. sodium sulfate b. sodium thiosulfate c. sodium bisulfate d. sodium bisulfite

b. sodium thiosulfate

Alkalinity of water is desirable at levels of: a. 0 to 30 mg/l b. 0 to 500 mg/l c. 30 to 100 mg/l d. 0 to 5 mg/l

c. 30 to 100 mg/l

Rocks such as serpentine, slate, soapstone, and marble belong to which class? a. Igneous b. Sedimentary c. Metamorphic d. Limestone

c. Metamorphic

The final product in biochemical oxidation of ammonia yields: a. Nitride b. Nitrite c. Nitrate d. Nitrogen

c. Nitrate

Algae development will cause all conditions except: a. Reduced water clarity b. Increased chlorine consumption c. Rapid fall in pH d. Slimy growth

c. Rapid fall in pH

If sufficient amounts of activated carbon in the powdered form are used, practically all tastes and odors are removed from water by a. Absorption b. Polymerization c. Adsorption d. oxidation

c. adsorption

The disinfecting ability of chlorine is affected most by: a. BOD b. temperature c. hydrogen ion concentration d. dissolved oxygen

c. hydrogen ion concentration

In a test conducted in North Carolina by the PHS in sandy soil, sewage organisms traveled a. only 10 feet b. 450 feet c. in excess of 200 feet d. 1,200 feet

c. in excess of 200 feet

Which would not be classified as a sedimentary formation? a. limestone b. peat c. olivine d. loess

c. olivine

Of the following, which are included as a major regulatory requirements in the Safe Drinking Water Act (SDWA)? a. sampling b. record keeping c. public information d. a and b e. b and c

c. public information

The Langelier index is used to determine the point of stability of:

calcium carbonate

Activated carbon is used to:

control tastes and odors

The pH of a solution in which apparent hydrogen ion concentration is equal to 1 x 10-8 moles per liter is: a. 2 b. 4 c. 6 d. 8

d. 8

Which contaminant in water is associated with methemoglobinemia? a. Zinc b. Lead c. Copper d. Nitrate

d. Nitrate

Backflow of nonpotable materials into the potable water system may occur by a) backpressure b) backsiphonage c) vacuum in the volume d) a and b above

d. a and b above

Cross-connections are frequent causes of disease resulting from a. back-siphonage of contaminated chemicals b. backflow of biologically contaminated liquids c. connection of the water supply to the sewer system d. all of the above

d. all of the above

Which of the following compounds would NOT contribute to water hardness? a. calcium sulfate b. magnesium sulfate c. calcium chloride d. sodium chloride

d. sodium chloride

Which of the following would be classified as a non-transient, non-community water system (NTNCWS)? a. water supply serving a campground b. water supply serving a small community c. water supply serving a highway rest area d. water supply serving a factory with at least 25 employees

d. water supply serving a factory with at least 25 employees

A well casing should be equipped with a vent and installed: a. With a sampling tap b. In a pit to prevent freezing c. With a turbine type pump d. With concrete used as grout

d. with concrete used as grout

What causes water hardness?

dissolved calcium and magnesium bicarbonates, sulfates, and chlorides

Another name for Epsom salts is:

magnesium sulfate

What is desalination?

the conversion of seawater or brackish water to fresh water

Water containing nitrates generally indicates:

Evidence of previous pollution

For their drinking water supply, over 95% of all farm families depend on:

Groundwater

What is used to properly seal a drilled well to prevent contamination of the water supply?

Grouting

Most cases of groundwater pollution occur in areas of:

High population

The manner in which water moves from place to place, changing from one form to another is called the:

Hydrologic cycle

The most practical method for removing nitrates from water is:

Ion exchange

What does it mean when a body of water has a high JTU?

It has high turbidity

Lakes having characteristics of being clean, high in DO, deep, and receiving few nutrients:

Oligotrophic (young lake)

The primary reason for the decline in the water table in some groundwater dependent areas of the world is:

Over pumping

Trihalomethanes are synthetic organic chemicals primarily created during what process?

Pre-chlorination process

The Amendments to the Safe Drinking Water Act do not cover:

Private wells

Control of infectious, intestinal diseases of humans requires:

Safe water, proper waste disposal, and personal hygiene

Xeriscape landscaping means:

Selecting plants that can thrive on natural precipitation

It has been estimated that waterborne disease worldwide accounts for an excess of:

250 million illnesses per year

Hydrogen sulfide can be fatal at exposure of:

300 ppm

Just to maintain bodily functions, a person needs:

4-12 pints of water each day

Residential cesspool and septic tank soil absorption systems discharge

400 million gallons of sewage into the ground each year

What is porosity?

A measure of the amount of water that can be held by a rock in its pores or voids, expressed as a percentage of the total volume

An example of a surface water supply would be:

A reservoir

What are some satisfactory solutions to the problem of chemical contamination in well systems?

Abandoning the well, connecting to a public water system, or building a new, properly constructed, drilled well.

The majority of the world's water is used in:

Agriculture

This substance is the first product of the decomposition of organic matter. Its presence in water usually indicates "fresh pollution" of sanitary significance. What is it?

Ammonia

The majority of fresh water is found:

As groundwater

Often over 90% of sodium arsenate can be removed by a. filtration b. coagulation c. ion exchange d. all of the above

B. coagulation

In domestic water well supplies, which two elements cause most hardness?

Ca and Mg

Reduction of the level of fluorides in drinking water can be accomplished by a. coagulation b. lime softening c. ion exchange d. all of the above

D. all of the above

What type of well is considered the most dependable source of water and is less likely to become contaminated?

Drilled well

The major problem associated with desalinization of water is:

The amount of energy required

Proper disinfection of water using chlorine depends on the concentration of chlorine plus:

The temperature of the water, the pH of the water, and the contact period.

The factor that will ultimately result in chronic water shortages is:

Unchecked population size

The flushometer valve is typically protected by

a non-pressure-type vacuum breaker

High concentrations of nitrates in drinking water are:

a possible cause of methemoglobinemia

Leachate from a garbage dump has been found to pollute wells: a. 2,000 feet away b. 1,400 feet away c. 100 feet away d. 50 feet away

a. 2,000 feet away

Which soil has the greatest % porosity? a. silt b. uniform sand c. gravel d. sandstone

a. silt

The DPD test is commonly used for the determination of:

chlorine or bromine

Masonry reservoirs of rural water supplies are called:

cisterns

Nephelometric Turbidity Units (NTU) are most commonly used to:

determine turbidity

The general type of subsurface formation in which groundwater contamination is likely to travel the farthest is:

limestone

The quiescent settling of water such as would occur in a reservoir, lake, or basin without the aid of chemicals is known as:

plain sedimentation

Methylene Blue Active Substance (MBAS) is a test to identify:

presence of detergents containing phosphates

Improperly located wells, allowing fecal pollution of the water supply, may lead to outbreaks of:

salmonellosis, shigellosis, cholera, hepatitis

Groundwater in the soil travels up through a plant's root system and then comes out from the leaf structure as: a. Transpiration b. Sublimation c. Evaporation d. Condensation

A: Transpiration

What is the best method of backflow control?

Air gap separation

The gases frequently found in water that encourage corrosion are a. Methane and oxygen b. Oxygen and carbon dioxide c. Chlorine and carbon dioxide d. Methane and hydrogen sulfide

B. Oxygen and carbon dioxide

In emergencies, small quantities of water can be disinfected by boiling or using a. Aluminum salts b. Tincture of iodine c. Salt tablets d. Direct exposure to sunlight for 22 hours

B. Tincture of iodine

Perhaps the greatest potential for reducing the demand for water could result from:

Better use of technology in agricultural irrigation

To improve the health and living standards among Third World populations, one of the best things that could be done is:

Increase the quantity of readily available water

What are some characteristics of groundwater?

Most bacteria are absent, evaporation is virtually non-existent, it is less expensive to treat than surface water.

The easiest and least expensive way to conserve water within most households is:

Repairing leaky toilet fixtures

The process whereby water that has fallen on land finds its way back to the oceans is called:

Run-off

What type of filter is recommended for use at small communities and rural places?

Slow sand filter

In the United States, saltwater intrusion into depleted aquifers is becoming a problem in:

Southern California

The substance commonly used as a coagulant in water treatment is:

aluminum sulfate

Hardness in drinking water is desirable at levels of: a. 80 to 150 mg/l b. 50 to 80 mg/l c. 0 to 50 mg/l d. 600 to 800 mg/l

b. 50 to 80 mg/l

Regulation of drinking water additives is the responsibility of: a. FDA b. EPA c. Dept. of Labor d. PHS

b. EPA

A water system serving one apartment building with three apartments, having a total of six residents is a Public Water Supply (PWS). a. True b. False

b. False

Which organism is NOT known as an iron bacterium? a. crenothrix b. Giardia lamblia c. gallionella d. leptothrix

b. Giardia lamblia

What conditions would result in the worst case of pipe damage due to corrosion?

soft water, low alkalinity, presence of oxygen

A general rule when surface waters are used for drinking water supplies is:

that they must be considered contaminated

A hydraulic ram is used to elevate a quantity of water to a higher elevation. Rams are powered by:

water