Residents in the Bellaire area of Ohio were warned not to drink tap water this week, it has emerged.
The water department revealed that hydrochloric acid was added to water supplies instead of fluoride at the local treatment plant.
Superintendent of the water department Kirk Baker assured residents that emergency crews were working to rectify the problem and advised them not to consume tap water until further notice.
A total of 40 pounds of the chemical was added to the water system by mistake.
Mr Baker commented that "it could have been a serious situation" but that "nothing major happened this time" due to the hasty response from emergency services.
Over the weekend, the Northeast Ohio Regional Sewer District called for extra charges to be added to water bills so it can better deal with storm water, reported The Plain Dealer.