A boil-water advisory was lifted on Monday for 4.3 million city water customers who had been taking the precaution since the blackout (search) that struck the state last week reduced water pressure.

Victor Mercado, director of the Detroit Water and Sewerage Department, said the decision went into effect at 3 p.m. EDT after officials received test results that showed the water was safe and wasn't contaminated after the blackout.

"Recent sampling throughout the system indicates the water is safe to drink," he said.

The drop in pressure brought with it the chance of contamination from bacteria (search). The advisory affected city water customers in eight southeast Michigan counties.

The Michigan Department of Environmental Quality (search) worked with the water department to assess the system before the advisory was lifted. The water department is required to have two water sample tests come back as negative for contamination in a 24-hour period before the boil-water advisory is lifted.

Normally, electricity powers the pumps that push water through the city's water system. Following Thursday's blackout, pressure dropped in the pipes and brought the chance that air and bacteria could enter the water supply.

The water system has backup generators at some of its plants. Those went into action after the blackout, but officials said the power wasn't enough to keep full pressure in the pipes. Some suburbs lost water service during the blackout.

Following the blackout, area restaurants were forced to use unorthodox methods to serve customers. Some used bottled water for cooking and drinking, while others boiled water to ensure that it was safe for their customers.

In Macomb County, the health department ordered the 2,300 bars and restaurants connected to Detroit's water supply to shut down because of local rules about water quality. Some restaurants there have defied that order and remained open.