Potable Water

Precious Water

As you know from previous readings, the comparison of soil is very important in the removal of both viruses and bacteria. Which of the following soil conditions is the most favorable for removal of viruses?

Fine loamy sand over coarse sand and gravel

Which of the following organisms are most resistant to unfavorable environmental conditions and indicate past and possibly intermittent pollution?

Clostridium Sporulates (found in our intestines) These bacteria can survive extreme conditions due to their ability to form spores, making them indicators of fecal contamination.

Which of the following wells is considered the most dependable source of water and is likely to become contaminated?

Drilled well

Which of the following is NOT considered a satisfactory solution to the problem of chemical contamination in well systems?

Boiling water

Which of the following chemicals is the most widely used to destroy microorganisms?

Chlorine

Which of the following us the BEST method of backflow control?

Air gap separation

Microscopic photosynthetic plants of the simplest forms, having neither roots, stems, nor leaves, that are associated with taste and odor, filter clogging, and other water problems

Algae

Control of infectious, intestinal disease of humans requires

Proper waste disposal and effective sanitation measures.

Drinking water standards generally specify that 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

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

Jackson Turbidity Units - it has high turbidity

The presence of which of the following is MOST EASILY identified by laboratory analysis in water contaminated by feces?

Coliform

Nephelometric Turbidity Units (NTU) are most commonly used to

Determine turbidity

The safe distance between a well and a waste disposal system is dependent on

chemical, physical, biological processes

What is the first step in evaluating the safety of a potential water system?

A detailed sanitary survey of the water supply - evaluate significance of pollution that might be present

What are examples of groundwater systems?

Dug, bored, driven wells; rocks, sand or earth springs; infiltration galleries

What causes water hardness?

Dissolved calcium and magnesium bicarbonates, sulfates, and chlorides

What is desalination?

The process of removing undesirable tastes and odors from domestic water supplies

The quality of surface water depends on

The watershed area drained, land use, location, and sources of pollution, and the natural agencies of purification

Which of the following is NOT commonly used for disinfection of water?

Silver Nitrate (common: Chlorine, chlorine-ammonia compounds, and ozone)

Hydro pneumatic or pressure-tank water systems are suitable for

Small communities, housing developments, private homes and estates, camps, food service operations, and hotels

The hydro pneumatic tank typically contains __ __ % of its volume as water

10-20%

Water containing nitrates generally indicates

Evidence of previous pollution

Hydrogen sulfide can be fatal exposure of

300 ppm

Diatomaceous earth filters

should be augmented by chlorination

The MOST practical method for removing nitrates from water is

Ion exchange

Which of the following is NOT a practical method for removal of cadmium?

Reverse osmosis (Best: ion exchange, lime softening, iron coagulation)

Back-siphonage may be prevented by all of the following methods EXCEPT

Barometric loop (Ideal: vacuum breakers, air gap separation, backpressure units)

Of the following, which is NOT a viable to be considered when deciding upon a safe distance between a well and a sewage disposal system?

The number of individuals utilizing the well

Microbial pollution travels only a short distance through …

sandy loam or clay (will travel indefinite distances through coarse sand and gravel, fissured rock, and dried-out cracked clay)

Typically, an abundant supply of groundwater may be yielded from

Sedimentary rocks (Sandstones, slates, and certain limestones)

An example of a surface water supply would be

A reservoir

Which of the following is use to properly seal a drilled well to prevent contamination of the water supply?

Grouting (cement; from within 5 ft of the top of the aquifer to the ground surface)

Which of the following compounds would NOT contribute to water hardness?

Sodium Chloride (What would: calcium sulfate, magnesium sulfate, and calcium chloride)

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 (for a month or longer. particularly if the source water is sewage-polluted river)

Which of the following is NOT a commonly accepted method or device to prevent back-siphonage?

Cross-connections (What is: vacuum breakers, air gap separation, and back pressure units)

Which of the following disinfecting compounds can be used at full strength for disinfection? (Emergency Disinfection)

Sodium hypochlorite

The type of filter that is recommended for use at small communities and rural places is the …

Slow sand filter

All of the following will generally vary directly with the quantity of water used for domestic purposes EXCEPT

Amount of minerals in the water (verses availability of water, habits of the people, and costs of water)

Groundwater in the soil travels up through a plant’s roots system and then comes out from the leaf structure as

Transpiration (which then evaporates into the atmosphere)

The type of water that makes it difficult to produce suds or to rinse laundry, dishes or food equipment is?

Hard water

A sanitary survey of a water system is necessary for what reasons?

To determine the safety and the adequacy of the water supply

The sources of water supply are divided into which of the following major classifications?

Groundwater and surface water (GW: dug, bored, driven, drilled wells; rock, sand, or earth springs) (SW: lake, reservoir, stream, pond, river and creeks)

The gas causing the distinct “rotten egg” odor in many water sources is

Hydrogen sulfide (also causes corrosion of iron, steel, and copper; and black stains on laundry)

High concentrations of nitrates in drinking water are

A possible cause of methemoglobinemia / “baby blue syndrome”

Turbidity of water well

Interfere with proper disinfection, harbor viruses / microorganisms, and causes tastes and odor

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 (Free ammonia is the FIRST product of decomp of organic matter)

The presence of which of the following elements in water treatment plant effluent is used as a measure of the filtration efficiency?

Aluminum (Al sulfate is commonly used as a coagulant in water treatment; excessive Al may pass through the filter w/ improper pH control)

One of the most common reasons for the contamination of wells drilled through rock, clay, or hardpan is

Failure to seal well castings properly (This helps prevent water movement between aquifers, protect aquifers, and prevent entry)

Proper disinfection of water using chlorine depends on the concentration of chlorine plus which of the following?

Temperature of the water, pH of the water, and contact period. (Plus: the amount of chlorine used & residual chlorine maintained, mixing and retention period, nitrogen compounds, and organic & suspended matter)

Which of the following is used to control the growth of algae and protozoa?

Filtration

The gases frequently found in water that encourage corrosion are

Oxygen and Carbon Dioxide

In emergencies, small quantities of water can be disinfected by boiling or using …

Tincture of iodine

Which of the following is not used to disinfect water?

Fluorine (helps prevent tooth decay)

Porosity is

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

The presence of which of the following in water would indicate past or possibly intermittent pollution?

Clostridium Perfringens (more resistant than Escherichia and Streptococci)

which of the following is a measure of the amount of light scattered by particles suspended in a water test sample?

Nephelometric Turbidity Units (NTU)

In testing for residual chlorine, which of the following determines free available chlorine with minimal interference from combined chlorine, iron, nitrates, and nitrites?

PDP-colorimetric method

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

Ozone is effective against

Amoebic and Giardia cysts, bacteria and phenols, humic acid, and viruses

Which of the following is (are) fundamental to the control of inorganic chemicals in drinking water?

Sanitary survey, identification of the sources, and determine the amounts of pollution

Often over 90% of sodium arsenate can be removed by

Coagulation

Reduction of the level of fluorides in drinking water can be accomplished by

Coagulation, lime softening, and ion exchange

What are the fundamental steps involved in the control of organic chemicals in drinking water?

Conduct sanitary survey to identify sources, types and amounts of pollutants (phase elimination)

Trihalomethanes are synthetic organic chemicals primarily created

During the pre-chlorination process

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

Calcium carbonate (positive; slightly positive is the goal. Water corrosivity = negative index)

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

Water (flowing in a pipe used to elevate a smaller quantity of water to a higher elevation)

A well casing should be equipped with a vent and installed

With concrete used as grout

Cross-connections are frequent causes of disease resulting from

Back-siphonage of contaminated chemicals, backflow of biologically contaminated liquids, and connection of water supply to the sewer system

The flushmeter valve is typically protected by

A non-pressure-type vacuum breaker (prevents back siphonage)

Which of the following statements is (are) true?

All surface water must be considered unsanitary unless given adequate treatment (and) when considering surface water as a water supply, the entire watershed must be surveyed

Which of the following statements is (are) true concerning the presence of coliform organisms in drinking water?

The drinking water should be considered unsanitary

When using pre-settling reservoirs (or upflow roughing filters) to eliminate heavy turbidity or pollution before treatment, what is the desirable retention time?

2 to 3 days

If sufficient amounts of activated carbon in the powdered form are used, practically all tastes and odors are removed from water by

Absorption (out of service for 1-2 days)

Is has been estimated that waterborne disease worldwide accounts for in excess of

250 millions illnesses per year (25,000 people die, primarily children, daily)

Residential cesspool and septic tank soil absorption systems discharge

400 million gallons of sewage into the ground each year

In a test conducted in North Carolina by the PHS in sandy soil, sewage organisms traveled (urine dye)

in excess of 200 ft

Leachate from a garbage dumb has been found to pollute wells

2,000 ft away

Hardness in drinking water is desirable at levels of

50 to 80 mg/1 (As water hardness increases, the lime requirement increases, making the Zeolite process more attractive)

Alkalinity of water is desirable at levels of

30-100 mg/1

What would be classified as a non-transient, non-community water system (NTNCWS)?

Water supply serving a factory with at least 25 employees (other acceptable answers: highway rest stops, restaurants, and public parks. Must serve at least 25 people for at least 60 days/year but not the same 25 ppl. If they are the same ppl, must serve them for 6 months/year.)

(T/F) A water system serving one apartment building with three apartments, having a total of 6 residents is a Public Water Supply (PWS)

False

What is included as a major regulatory requirements in the Safe Drinking Water Act (SDWA)?

Public information

The Primary Drinking Water Standards

Apply to community water and non-transient, non-community water systems and are health-related and enforceable

(T/F) The Maximum Contaminant Level (MCL) is the highest concentration of a contaminant that is allowed in a water system

True

Which of the following is NOT included in the 9 contaminant groups?

Microorganisms (Included: volatile organic chemicals, turbidity, lead and copper, nitrate and nitrite)

Which would NOT be classified as a sedimentary formation?

Olivine (Sedimentary examples: sand and gravel, clay, silt, chalk, limestone, fossils, gypsum, salt, peat, shale, conglomerates, loess, and sandshell)

Rocks such as serpentine, slate, soapstone, and marble belong to which class?

Metamorphic (Produced by the alteration of igneous and sedimentary rocks, generally by heat and pressure. Examples: gneisses and schists, quartzites, slate, marbles, serpentines and soapstone)

Which solid had the greatest % porosity?

Silt (broken rock particles that are larger than clay but smaller than sand. Porosity is the amount of water that can be held by a rock or solid in its pores. EX: clay has 45-55% porosity)

Which is included in the sanitary survey of groundwater supplies?

Aquifer drainage area and local geology, nature of soil, rock, strata, and local geology, AND land use if habitation, sources of pollution, and local geology

When collecting bacteriological samples that have been chlorinated, what chemical is used to dechlorinate the water?

Sodium Thiosulfate (should be examined within 6-12 hours)

What is the purpose of using the sweeping motion when collecting water samples?

Prohibits contamination from sample hands - so water touching the hands wont enter the bottle

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

Coliform

Which soil condition is most favorable for removal of viruses?

Fine loamy sand over coarse sand and gravel

What water constituent has been associated with staining plumbing and clothing dark brown or black?

Mn (0.1 mg/1; also leads to metallic taste)

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

Presence of detergents containing phosphates (Presence of alkyl benzene sulfate (ABS and linear alkylate sulfonate (LAS). It is a measure of the apparent detergent of foaming agent and hence sewage presence)

In domestic water samples. which two elements cause most hardness?

Calcium and Magnessium

Which residual test for chlorine would be LEAST desirable?

OTA (Desirable: SNORT (stabilized neutral orthotolidine), Methyl orange, DPD (diethyl-p-phenylenediamine), FACTS (Free Available Chlorine Tests)

Which would NOT be used to coagulate?

Sodium hypochlorite (chlorination) (would: black alum, chlorinated copperas, and ferric chloride)

Which organism is NOT known as an iron bacterium?

Giardia Lamblia (is: crenothrix, gallionella, and leptothrix)

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

Soft water, low alkalinity, presence of oxygen (pH and presence of carbon dioxide, low hardness)