Our monitoring has sometimes found small concentrations of Giardia cysts in the water prior to treatment. Disinfection with chlorine is VERY effective in destroying Giardia in water. This is Seattle's current treatment method. Additional treatment processes are being added in the future to provide additional layers of water quality protection, such as the new Tolt Treatment Facility and Cedar Treatment Facility . Giardia lamblia is a microscopic protozoan which, when ingested, can cause giardiasis.
Giardiasis is a gastro-intestinal disease manifested by diarrhea, fatigue, and cramps.
Symptoms can last anywhere from a few days to months. Warm blooded animals, such as elk, deer, muskrats, beavers, domestic or farm animals, and humans can be hosts for this protozoan. Giardia is excreted into the environment from the fecal material of the warm blooded hosts. It is then washed into lakes, rivers, and streams. For this reason, consumption of untreated water while hiking, camping or at any time is not recommended.