Corrosion control in water treatment involves which actions?

• A. Adjust pH, alkalinity, phosphate inhibitors
• B. Increase disinfectant residual only
• C. Remove all minerals
• D. Add iron and manganese

Answer: (A)

Corrosion control focuses on changing water chemistry so metals in pipes stay in a less corrosive form. The most effective approach combines adjusting pH to a level that reduces corrosivity with maintaining adequate alkalinity to buffer pH changes and keep the water from becoming too aggressive toward metal surfaces. Adding phosphate inhibitors, like orthophosphate, helps form a protective film on the interior of pipes, which lowers the rate of metal dissolution and reduces lead and copper release.

Increasing disinfectant residual primarily targets microbial control, not the chemical reactions that cause corrosion, so it isn’t a direct corrosion-control measure. Removing all minerals isn’t desirable because minerals provide buffering capacity and stability to the water; stripping them away can make the water more corrosive in some cases. Adding iron and manganese introduces dissolved metals and can lead to other issues, not a mitigation of corrosion.