Residents of Heidelberg in southwestern Germany were concerned their water was contaminated on Thursday after some residents began noticing a bluish colour. City officials warned residents to not drink the water while they investigated the change in tint.
On Thursday morning, residents of the Heidelberg area raised the alarm by posting photos of the blue water on social media.
Police and fire brigades drove around the city alerting residents through loudspeakers to not touch the water.
In the afternoon, the city’s health department said in a press release that the water's discolouration was due to natural causes.
"Water is a natural product. Depending on its composition, different colourings may occur without impairing its suitability as drinking water."
Samples taken at the Entensee plant, which supplies water for the city of Dossenheim and northern Heidelberg, and at local consumption points complied with drinking water regulations, said the statement, adding that warnings were just a precautionary measure to protect the local population.
The warning by officials was cancelled at 4 p.m. CET on Thursday.