Giardia
Giardia is a microscopic organism found in untreated surface water. Since 1994, the Southern Nevada Water System has tested regularly for this organism throughout the water treatment and distribution systems.

Giardiasis, the illness associated with this pathogen, may cause severe diarrhea, abdominal cramps, malaise and weight loss. Vomiting, chills, headache and fever can occur in more serious cases. This may pose a serious health risk to individuals with severely suppressed immune systems.

One of the most effective safeguards against Giardiasis is ozonation, a water treatment process which uses ozone to destroy pathogenic microorganisms. Both the Alfred Merritt Smith Water Treatment Facility and the River Mountains Water Treatment Facility have incorporated this advanced disinfection technology into their treatment processes.

Giardiasis outbreaks occur more frequently in the Northeast and Northwest, possibly due to the extended winter season and low surface water temperatures. Most community outbreaks occurred in water systems with minimum treatment to its surface water source. A giardiasis outbreak usually occurs when conditions include low water temperatures, poor sanitation upstream, beaver colonies (or other ground animals such as muskrats) located near the water supply intake and inadequate water treatment.