EPHRATA — A boil-water advisory remains in effect in Ephrata, at least until city officials learn the results of tests on water samples taken Monday. Full test results are expected Wednesday morning.

The advisory was issued for the northeast and southeast parts of town, wrote city Administrator Ray Towry in a Tuesday press release. It does not include the Grandview Heights neighborhood.

The boil-water advisory was issued Monday afternoon following a malfunction of sensors that regulate the city’s water reservoir system. City officials expected some preliminary test results Tuesday night.

“Initial calls received Sunday morning indicated community members experienced low water pressure,” Towry wrote. “City staff (investigated) and found low, but not empty, reservoirs and a malfunctioning water monitoring system. The malfunction prevented the alarm system from issuing a warning that notifies staff of irregularities during non-business hours. Staff manually turned on well pumps, overriding the automated system, and monitored the reservoirs as they refilled.

“Monday morning new information became available that there may have been ‘negative pressure,’ or backflow, into the water system. After confirming that some residents in various locations of town had gotten air in their pipes, a ‘negative pressure’ indication, city staff contacted the state’s drinking water officials for guidance. As a result of this collaboration, the city issued a boil advisory as a precautionary measure,” he wrote.

Ephrata was required by state officials to chlorinate its drinking water system several years ago.

“The disinfectant levels were tested and at state standards. The lines in the northeast and southeast sections (of the city) were also flushed as water came back online to expel any of the air or potentially stagnant water,” Towry wrote.

In the meantime, people in the affected areas are being advised to boil water for at least one minute and then let it cool before drinking it. Boiled water or bottled water should be used for drinking, brushing teeth, washing dishes and food preparation until further notice, he wrote.

Cheryl Schweizer may be reached via email at [email protected].