- How contaminated is Dental Water?

"In the United States, you should be able to expect that your water is safe to drink, or "potable" by government standards. Usually, a municipal plant will deliver water containining less than 100 colony-forming units of heterotrophic bacterial per millimeter (cfu/ml) which is considered "safe". According to US Army standads, water should not be consumed if it is known to contain more than 500 cfu/ml. Assuming that safe, potable water is being delivered to dental facilities, you will probably be shocked to learn that by the time the water exits the dental unit water lines - high speed hand pieces, air-water syringes and ultrasonic tooth scalers - it is almost always grossly contaminated, dangerous and potentially deadly. This water is being sprayed into the mouths of patients during routine dental treatment. It also forms and aerosol and can therefore contaminate equipment, surfaces, clothing, skin and even the air that patients and staff members breathe. How can this happen? How can health professionals use water that often averages over 500,000 cfu/ml? That is 1,000 timess greater than what is even allowed by US Army standards!"

Robert A. Silver, DDS, in Water Conditioning & Purification, September 1995.