Under NC PWSS Rules, the control and upward adjustment of the pH of drinking water is required if it is below what value?

Under NC PWSS Rules, the control and upward adjustment of the pH of drinking water is required if it is below what value?

• A. 7.0
• B. 6.0
• C. 5.5
• D. 6.5

Answer: (D)

Maintaining pH at a level that minimizes pipe corrosion is a key requirement for protecting drinking water quality. In NC PWSS Rules, there is a specific trigger: if the pH of the water falls below 6.5, the system must actively control and raise it. The reason is that water with pH under 6.5 is more acidic and can corrode distribution materials, increasing the risk of metals (like lead) leaching into the water and potentially compromising disinfection effectiveness. Raising the pH to at least 6.5 helps form protective scales on pipes and reduces metal solubility, contributing to safer, more stable water chemistry. Values like 5.5 or 6.0 fall below this threshold and require adjustment, while 7.0 is above the minimum and would not trigger the required action. The essential point is that 6.5 is the regulatory floor for initiating pH adjustment.

Maintaining pH at a level that minimizes pipe corrosion is a key requirement for protecting drinking water quality. In NC PWSS Rules, there is a specific trigger: if the pH of the water falls below 6.5, the system must actively control and raise it. The reason is that water with pH under 6.5 is more acidic and can corrode distribution materials, increasing the risk of metals (like lead) leaching into the water and potentially compromising disinfection effectiveness. Raising the pH to at least 6.5 helps form protective scales on pipes and reduces metal solubility, contributing to safer, more stable water chemistry. Values like 5.5 or 6.0 fall below this threshold and require adjustment, while 7.0 is above the minimum and would not trigger the required action. The essential point is that 6.5 is the regulatory floor for initiating pH adjustment.