SIERRA VISTA — East Slope Water Company customers can safely drink their water again, after a boil warning was lifted Friday afternoon.

“East Slope Water is pleased to report that the latest sample results have been released from the laboratory and have come back negative for E. coli. At this time it is no longer necessary to boil the water. We apologize for any inconvenience and thank you for your patience,” said a press release from  Paul Juhl, office manager for Southwest Utility Management Inc., which manages East Slope.

Affected customers were told Wednesday by the company to boil their water for at least two minutes before drinking or cooking, after E. coli was detected in the closed well system during a routine inspection.

“It’s very difficult to tell exactly what could have caused this,” said Juhl in a phone interview before the boil alert was lifted.

He said because the affected system is older, it can be prone to breaks and leaks, which in turn can cause contamination like the E. coli that was discovered earlier this week.

Since the initial discovery, the company worked to disinfect and flush the system, sending new samples to the lab for analysis, leading to the ban being lifted just after 3 p.m. Friday, once the new samples came back negative for contamination.

Juhl said the company distributed a case of water to each of the 57 customers that were affected by the contamination, either hand-delivering them to customers or leaving the case on the doorstep if residents didn’t answer.

“We initially delivered water to each of the affected customers except one, and when we received a call indicating they needed some, we rushed out there right away to bring it to them,” Juhl said.

Some residents didn’t seem overly concerned with the contamination.

“It really doesn’t bother me that much besides I can’t drink the water,” said customer Marietta Conley. She said the company came to the house to let her know about the incident, then called her later the same evening to follow up.

Conley was happy with the company’s reaction.

“I think they handled it well, under the circumstances,” she said. “They let us know right away what was going on and made sure we weren’t drinking the water.”

According to the Centers for Disease Control and Prevention website, E. coli is commonly found on a small number of cattle farms, and if infected animal waste comes into contact with a water source, it can lead to contamination.

“Waste can enter the water through different ways, including sewage overflows, sewage systems that are not working properly, polluted stormwater runoff and agricultural runoff. Wells may be more vulnerable to such contamination after flooding, particularly if the wells are shallow, have been dug or bored, or have been submerged by floodwater for long periods of time,” according to the CDC.

Although most forms of E. coli are actually harmless, its presence means the water has been contaminated with fecal matter, which can lead to illness. Some forms of E. coli, including E. coli O157:H7, can cause diarrhea, cramps and even kidney failure.