Leviticus 15:13 (written 3000 years ago): "And when he that has an issue is cleansed of his issue; then he shall number to himself seven days for his cleansing, and wash his clothes, and bathe his flesh in running water, and shall be clean."
The Bible said that when dealing with disease, hands should be washed under running water. Up until 100 years ago doctors washed their hands in a basin of still water, resulting in the death of multitudes. We now know that doctors must wash their hands under running water. From, The Evidence Bible