Which of the following is NOT a common water treatment method?

Distillation is indeed not a common water treatment method employed for municipal water purification on a broad scale. While distillation involves heating water to create vapor and then cooling it to obtain liquid, which effectively removes impurities and contaminants, it is primarily used for specific applications, such as producing distilled water or in certain industrial processes.

In contrast, filtration, chlorination, and boiling are widely utilized in community water treatment systems. Filtration removes particulates and some contaminants through a physical barrier, chlorination is a chemical treatment method that disinfects water by killing harmful bacteria and pathogens, and boiling is a simple yet effective method for pathogen elimination. Each of these methods serves a typical role in ensuring water safety and quality for public use, which is why they are more prevalent in community water treatments compared to distillation.