The city of Mercer Island says 400 waters samples tested since Oct. 2 have all been found to be free of E. coli the prompted back-to-back boil water advisories.
The Seattle suburb also said Wednesday that one resident who became sick during the incident was tested and found to have a serious strain of the bacteria — 0157:H7. But none of the contaminated water samples had that strain. There are other sources of E. coli in the environment, so the city says it’s not possible to confirm the water caused that illness.
No source of the E. coli contamination was ever found on Mercer Island.