Which type of corrosion-control inhibitor may stimulate bacterial growth?

Phosphate-based products are used in water distribution systems primarily for corrosion control. These inhibitors work by forming a protective film on metal surfaces and can help to minimize the leaching of metals like lead and copper into drinking water. However, one noteworthy characteristic of phosphate is that it can act as a nutrient source for certain types of bacteria, particularly those that can thrive in water environments.

When phosphate levels are elevated, it can promote the growth of biofilms and specific bacterial populations that may require phosphorus for their metabolic processes. This stimulation of bacterial growth can lead to issues such as microbial-induced corrosion, which can further compromise the integrity of pipelines and result in water quality concerns.

In contrast, the other options, such as lead-based products, chlorine-based products, and borate-based products, do not create the same conditions for bacterial growth or may even inhibit it. For instance, chlorine is widely used not only for disinfection purposes but also has properties that help in controlling microbial growth. Therefore, the use of phosphate-based products, while beneficial for controlling corrosion, poses a potential risk by inadvertently fostering bacterial activity in the water distribution system.