In the pH range used to minimize lead leaching from water distribution systems, which pH range is specified?

• A. 6-9
• B. 5-7
• C. 7-10
• D. 4-8

Answer: (A)

Lead in drinking water comes from corrosion of lead-containing materials, and the amount that dissolves depends on pH. When water is more acidic (lower pH), it corrodes metals more and dissolves more lead; raising pH reduces lead solubility and helps form protective scales on metal surfaces. Utilities aim for a moderate, slightly basic range to minimize lead leaching, typically around six to nine. Staying within this window keeps the water from being too corrosive while avoiding problems that can come with very high pH. If the water falls outside this range, either more lead could dissolve at the low end or other water quality issues can arise at the high end.