SMALL WATER SYSTEMS (ABC) EXAM QUESTIONS WITH
ACCURATE ANSWERS
1) What chlorine concentration should be produced when disinfecting a well or well
pump? -- Answer ✔✔ 50 mg/L
2) When disinfecting a new or repaired main, what is the minimum chlorine residual at
the extreme end of the main after standing for 24 hours? -- Answer ✔✔ 25 mg/L
3) The pumping water level is best defined as the distance from the top of the well to
the? -- Answer ✔✔ Water after the pump has been operating for a period of time
4) A mixture of air and gas is considered hazardous when the mixture exceeds what
percentage of the lower explosive limit? LEL? -- Answer ✔✔ 10%
5) What safety procedure should an operator always follow when mixing a solution of
sodium hypochlorite aka liquid bleach and fresh water? -- Answer ✔✔ Wear goggles
and gloves when handling hypochlorite
6) Which form of hypochlorite is the most dangerous to handle? -- Answer ✔✔
Calcium
ACCURATE ANSWERS
1) What chlorine concentration should be produced when disinfecting a well or well
pump? -- Answer ✔✔ 50 mg/L
2) When disinfecting a new or repaired main, what is the minimum chlorine residual at
the extreme end of the main after standing for 24 hours? -- Answer ✔✔ 25 mg/L
3) The pumping water level is best defined as the distance from the top of the well to
the? -- Answer ✔✔ Water after the pump has been operating for a period of time
4) A mixture of air and gas is considered hazardous when the mixture exceeds what
percentage of the lower explosive limit? LEL? -- Answer ✔✔ 10%
5) What safety procedure should an operator always follow when mixing a solution of
sodium hypochlorite aka liquid bleach and fresh water? -- Answer ✔✔ Wear goggles
and gloves when handling hypochlorite
6) Which form of hypochlorite is the most dangerous to handle? -- Answer ✔✔
Calcium
