Contractor Exam Questions And

CA C55 Water Conditioning Contractor Exam Questions And Correct Answers (Verified Answers) Plus Rationale2026 Q&A| Instant Download Pdf

• Which of the following is the primary purpose of a water softener?
• Remove chlorine
• Remove hardness ions
• Filter sediment
• Add fluoride

Rationale: Water softeners are designed to remove calcium and magnesium

ions that cause hardness in water.

• What type of resin is commonly used in ion-exchange water softeners?
• Activated carbon
• Sulfonated polystyrene
• Sand
• Zeolite

Rationale: Sulfonated polystyrene resins are cation-exchange resins

commonly used to replace calcium and magnesium ions with sodium or potassium ions.

• What is the function of a backwash cycle in a water softener?
• Add salt
• Clean and regenerate the resin bed 1 / 3

• Reduce water pressure
• Inject chemicals

Rationale: Backwashing removes accumulated hardness and debris from

the resin bed, preparing it for regeneration.

• What is the main cause of scale formation in plumbing systems?
• Sediment
• Bacteria
• Hard water minerals
• Organic matter

Rationale: Calcium and magnesium ions in hard water precipitate to form

scale on pipes and fixtures.

• Which water quality parameter measures water hardness?
• pH
• Chlorine
• ppm of CaCO₃
• Turbidity

Rationale: Water hardness is usually expressed as parts per million (ppm)

or milligrams per liter (mg/L) of calcium carbonate.

• What is the ideal regeneration frequency for a typical household water

softener?

• Daily
• Monthly
• Every 2–3 days depending on usage
• Yearly

Rationale: Regeneration frequency depends on water usage and hardness

levels to maintain soft water efficiently.

• Which method is commonly used to remove iron from water?
• Reverse osmosis
• Oxidation/filtration
• Distillation
• Carbon filtration 2 / 3

Rationale: Iron can be removed using oxidation followed by filtration to

precipitate and trap iron particles.

• What is the main disadvantage of using sodium-based softeners?
• Low efficiency
• Increases sodium content in water
• Cannot remove calcium
• High maintenance cost

Rationale: Sodium softeners replace hardness ions with sodium, which can

increase the sodium content in drinking water.

• Which water treatment device is most effective in removing suspended

solids?

• Water softener
• UV light
• Sediment filter
• Carbon filter

Rationale: Sediment filters are designed to trap sand, silt, and other

suspended particles.

• What type of filter media is commonly used in a multimedia

filter?

• Sand, anthracite, garnet
• Gravel only
• Activated carbon only
• Zeolite

Rationale: Multimedia filters use layers of sand, anthracite, and garnet to

remove particles of varying sizes.

• What is the purpose of a reverse osmosis (RO) system?
• Soften water
• Remove dissolved solids
• Add minerals
• Disinfect water
• / 3