They try not to pollute it. For example, treatment facilities are being built at industrial enterprises so that various harmful impurities do not get into the water, which can damage the ecosystem of the reservoir. Also, conscious people, when they are resting near the water, do not throw anything there, bottles, chocolate wrappers, etc.
One of the components of a person's success in our time is receiving modern high-quality education, mastering the knowledge, skills and abilities necessary for life in society. A person today needs to study almost all his life, mastering everything new and new, acquiring the necessary professional qualities.