Water Distribution Operator Class D Exam Questions & Answers 100% Correct

What are some physical characteristics of water? - Answer Temperature, turbidity, color, taste, odor What are some chemical characteristics of water? - Answer Hardness, pH, solids, and gases What is turbidity? - Answer the amount of suspended matter, such as clay, silt, organic matter, and microorganisms in water T/F Water is never found pure in nature. - Answer True Is turbidity more of a problem in groundwater or surface water? - Answer Surface water A system's filtered water must be _______ Nephelometric Turbidity Units (NTU) or less in at least 95% of the measurements taken each month, and no sample can exceed _____ NTU. - Answer 0.3 1 T/F True color is dissolved in water (in solution) and cannot be removed by filtering. - Answer True. Tea in water is an example of true color. Suspended color is called _______ color. - Answer apparent Color above ______ units is objectionable in a public water supply. - Answer 15 units A scale called the ________ measures odor. - Answer Threshold Odor Number (TON) Odor greater than a scale of _______ is undesirable. - Answer 3 Taste and odors in water result from _______, bacteria, decaying organic matter, gases, and chemicals such as manganese, zinc, copper, iron, magnesium, sodium, and potassium. - Answer algae Chemical characteristics of water generally cannot be detected by sight, smell, or taste and must be determined by __________. - Answer laboratory analysis Chemical laboratory analysis must be sampled _______ per year for surface water and normally _______ for groundwater. - Answer once/year for surface water once every three years for groundwater Water weighs ______ lbs/gal. - Answer 8.34 lbs/gal T/F For water, 1 mg/L is equal to 1 part per million (ppm) by weight. - Answer True Which two minerals mainly cause hardness in water? - Answer Calcium and magnesium Is hardness more of a problem in groundwater or surface water? - Answer Groundwater Water is considered hard when it exceeds _______. - Answer 100 mg/L of calcium carbonate The pH scale ranges from _____ to _____. - Answer 0 to 14 On the pH scale: 0 to <7 is ______. 7 is _______. >7 to 14 is ______. - Answer Acidic Neutral Basic or alkaline Sulfuric, hydrochloric, and nitric acids can be used to ______ pH. Caustic, lime, or soda ash can be used to ______ pH. - Answer Lower Raise Suspended solids can be removed by ________. - Answer Filtration Can dissolved solids be removed by filtration? - Answer No Total dissolved solids should not exceed________. - Answer 1000 mg/L What are three common gasses found in water? - Answer Hydrogen sulfide, carbon dioxide, and methane Excess ________ can cause blue baby syndrome. - Answer Nitrogen or Nitrates What is the major source of nitrogen into drinking water? - Answer Fertilizer and animal waste carried by rainwater runoff What is the EPA primary MCL (maximum contaminant level) for fluoride? - Answer 4.0 mg/L At what level will fluoride cause mottling of teeth, a condition known as fluorosis? - Answer 4.0 mg/L What is the state of Texas secondary standard for fluoride? - Answer 2.0 mg/L Trihalomethanes (THM) and Haloacetic Acids (HAA) are byproducts of drinking water ________. - Answer chlorination THM's and HAA's are byproducts formed when chlorine reacts with dissolved _________. - Answer natural organic matter, mostly plant life Combining chlorine with _______ greatly reduces THM and HAA formation. - Answer ammonia Is surface water or groundwater more likely to contain natural organic matter? - Answer surface water What is chloramine? - Answer Chlorine combined with ammonia What is free chlorine? - Answer Chlorine not combined with ammonia. Most groundwater systems do not have organic matter (which could cause THM and HAA byproducts) and therefore are allowed to use uncombined chlorine, called free chlorine. Why are most surface water treatment plants required to combine chlorine with ammonia (chloramine) before disinfecting the treated water? - Answer Surface water usually contains natural organics, and combining chlorine with ammonia greatly reduces THM and HAA formation. What is the MCL (maximum contaminant level) for THMs? - Answer 0.08 mg/L What is the MCL (maximum contaminant level) for HAAs? - Answer 0.06 mg/L The MCLG (maximum contaminant level goal) for lead is zero. What is the action level for lead? (in 10% or more of the samples) - Answer 0.015 mg/L The MCLG (maximum contaminant level goal) for copper is 1.3 mg/L. What is the action level for copper? (in 10% or more of the samples) - Answer 1.3 mg/L For lead and copper samples, how long must water be in the pipe with no flow before the sample is taken? - Answer 6-18 hours What type of sample requires a one-liter, first-draw sample taken from the cold water kitchen or bathroom tap? - Answer Lead and Copper Who may take a lead and copper sample? - Answer Utility personnel or trained residents may take samples, and utility personnel will take the samples to an approved lab. T/F Larger population sizes require more sampling sites for the lead and copper rule. - Answer True T/F Lead and copper initial sampling is required, and then if requirements are met for consecutive periods, sampling schedule can be reduced to reduced monitoring. - Answer True