NORRISTOWN, Pa. (CBS) –Pennsylvania American Water says a boil water advisory is still in effect for customers in portions of Lower Providence Township.

The advisorywas originally issued Thursday night following the loss of water pressure in one of its storage tanks. Approximately 750 customers are affected.

“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 or back-siphonage. As a result, there is an increased chance that the water might contain disease-causing organisms,” officials said in a news release.

These organisms include bacteria, viruses and parasites, which can cause symptoms such as nausea, cramps, diarrhea and associated headaches.

Residents are urged to bring all water to a rolling boil, let it boil for one minute, and cool before using, or use bottled water. You should use boil or bottled water for drinking, making ice, washing dishes, brushing teeth and food preparation until further notice.

They are hoping to lift the advisory on Saturday.

“We are required to conduct two sets of water samples over two days to confirm that nothing harmful entered the water system, and it takes 24 hours until lab results are available,” officials said.

For more information, contact Pennsylvania American Water’s customer service center at (800) 565-7292, or CLICK HERE.