One of the most important reasons for only using reliable water source is to reduce?

The right answer is The number of parasites, such as Cyclospora Cayetanensis.

The health risks associated with water are due to the use of polluted water, unfit for the intended use, for example:

- Consumption of water (beverage, ...), live products or products grown in aquatic environments (shellfish, ...);

- Swimming ;

- Use in a hospital environment (hot water, ultra pure water, ...).

Depending on the pollutants, the health risk is of an infectious nature (viruses, bacteria, parasites, fungi), chemical (mineral, organic), or physical (thermal, radioactive).

The risks involved are more or less long term. Some are known and proven for health, and others are suspected or even emerging.

the fossil record provides evidence of a common ancestor to many species.