Question

Which chemicals are used to this disinfect rainwater?

Answer 1

chlorine
it will helps to clense the water

Answer 2

Boiling water can kill some pathogens, but it does not remove heavy metals, nitrate, pesticides, or other chemical contamination. Chlorine, iodine, andozone are most often used for chemical disinfection. Chlorination can leave potentially toxic by-products, plus it doesn't kill all cysts or viruses.