What do pathogenic organisms do?

Pathogenic organisms are microorganisms that can cause disease in humans, animals, and plants. These include bacteria, viruses, protozoa, and fungi that have the potential to infect hosts and lead to various health issues. Their presence in water systems is a significant concern, as they can cause waterborne diseases, posing serious health risks to the public.

This understanding is crucial in the context of water treatment and management, where the primary goal is to eliminate or reduce pathogens to safe levels to ensure the water is safe for consumption and use. The other options do not accurately reflect the role of pathogenic organisms, as they either imply a beneficial effect or a role in processes that promote safety rather than harm.