What is a common disadvantage of using caustic soda to soften hard water?

• A. More expensive
• B. Harder to store
• C. Reduces softening efficiency
• D. Increases corrosion risk

Answer: (A)

Caustic soda is effective at softening by raising pH and precipitating hardness-causing compounds, but the practical drawback is the ongoing operating cost. The chemical itself is relatively expensive, and dosing must be continuous and precisely controlled, which adds to labor, monitoring, and reliability requirements. All of this drives up the total cost of treatment compared with other softening methods. While storage and safety considerations are real, they are typically managed as part of handling a hazardous chemical and don’t outweigh the recurring expense in most assessments. Reducing softening efficiency isn’t the issue here, and while corrosion risk can be a concern if pH isn’t properly controlled, the most consistent and notable disadvantage cited is the higher cost.