CRESTON, Iowa — Thousands of people in nine Iowa counties have been without drinking water for days because of a filtration system failure that won't be fixed until this weekend at the earliest.

A membrane filtration system failure at the Twelve Mile Water Plant in Creston has left residents in the region without water since June 1, The Des Moines Register reported .

Residents have been advised to boil tap water before consumption to avoid potential bacteria, viruses and parasites that could cause nausea, cramps, diarrhea and headaches.

The water is safe for bathing and for pets and livestock, said Dan McIntosh, the general manager of the Southern Iowa Rural Water Association and Creston Water Works' treatment plant.

It's unclear why the system failed last week, McIntosh said. The utility has ordered new equipment from a Hungarian supplier. State and federal officials have helped expedite the shipping process, the utility said.

"The membranes are about $1 million," McIntosh said. "It's not something you can just keep on a shelf."

The utility will begin restoring water services to customers this weekend, though the work will be gradual, McIntosh said. Creston residents will likely be the first to get potable water, followed by surrounding communities served by the water association.

"It's going to be a while," McIntosh said. "We'll know more after we get the treatment plant running."

In the meantime, residents will continue to boil water or buy it bottled. Hy-Vee has donated nearly 20,000 gallons of bottled water to stores in Creston, Bedford and Mount Ayr.

Suanne Peterson lives in Creston. She has purchased at least 6 gallons of drinking water from the store.

"We go through it fast," she said. "With drinking water, even if it's boiled, I just don't trust it."

Creston Water Work and Water Association officials will consider giving residents a discount on their water bills, McIntosh said.