Pennsylvania American Water Saturday issued a precautionary boil water advisory for 900 customers in portions of the City of Butler, Butler Township and Center Township. 

Pennsylvania American Water experienced a loss in positive water pressure Saturday at a water storage tank in the City of Butler following a 12-inch water main break. The broken main limited the company's ability to replenish the water storage tank and local system.

A loss of positive water pressure is a signal of the existence of conditions that could allow contamination to enter the distribution system through backflow by back-pressure. As a result, there is an increased chance that the water might contain disease-causing organisms.

Bottled water will be available at the following locations:

Saturday: Sears parking lot at the Clearview Mall from 1 p.m. – 9 p.m.

Sunday: Pennsylvania American Water's Butler Water Treatment Plant, which is located at 203 Oneida Valley Road, from 7 a.m. – 7 p.m.

Click here for a map of those affected: http://www.onsolve360.com/alert?id=9-37801

This is a breaking news report. Check back for more information.