In a drinking water treatment plant, some employees accidentally add 176 l of hydrochloric acid (HCl) instead of 4.5 million fluoride in the water system around 11 pm. They discover their mistake the next day by noticing a strong odor and an abnormal pH in the treated water. The environmental protection agency (EPA) and emergency services are informed of the incident. In doubt over the HCl quantity, local authorities urge the population, about 2400 people, to stop drinking tap water. Several companies and schools are closed for the day. The distribution system is flushed and the water can be consumed again at 12:30. Services of the local hospital informed that 3 persons had been admitted with minor disorders that may have been caused by highly diluted HCl in water (nausea, dry mouth, diarrhea).

An investigation shows that the supplier of fluoride and HCl had conditioned the 2 products in a similar packaging (size, color), and that employees of the station had not checked the labels before using the drums. The plant manager estimates that the accident responsability is split between his company and the occasional supplier.