Lab tests now show the tap water in King County Water District 54 meets safe drinking standards.
The health department says E.coli was discovered Saturday night during routine tests, and ordered 5,000 customers in Des Moines and Normandy Park to boil the water or drink bottled. The bacteria can cause diarrhea and vomiting, and in severe cases can be life threatening in children and older adults.
The health department ordered 39 restaurants in the region to close during the advisory. The boil order also affected Des Moines Elementary, which remained open for classes but had water and lunches trucked in from other locations outside the area.
The water system was inspected Monday but found no obvious source of the E.Coli, but health officials say that is often the case because much of every water distribution's system is buried underground.
There were no reports of anyone getting sick.