Some of the chain’s eight stores in Hanoi's southwestern districts reopened last Saturday, and the remaining on Monday, a Starbucks representative said.

Although a customer service agent had said earlier that seven stores had been closed, Starbucks confirmed Tuesday that the correct number was eight.

Starbucks has hired a unit to test the tap water at its stores and results show that the water is safe for consumption, the representative told VnExpress International.

The eight Starbucks stores that closed last Friday were in the districts of Cau Giay, Ha Dong and Nam Tu Liem, all of which get tap water sourced from the Da River in the northern Hoa Binh Province.

The water in a section of this river was contaminated when a 2.5 ton truck on October 8 dumped used oil into a mountain creek that connects with the river. About a million Hanoi residents, or one eighth of the capital’s population, were affected.

Hanoi officials had said last Thursday that the tap water samples collected a few days earlier had passed safety tests, but persisted with the advice that residents refrain from using it for drinking or cooking. They are still to amend the advice.

As of Sunday, three people who dumped the used oil into the creek had been arrested. Police said they were continuing to investigate the role of other individuals or organizations in the incident.