Sarah Bennett, assistant town manager for Lisbon, helps pass out cases of bottled water to residents Friday at the Lisbon Public Works Department. Daryn Slover/Sun Journal

LISBON — After roughly 24 hours without safe drinking water, Lisbon residents hooked to the public water system can now drink the water, the Department of Health and Human Services announced Friday afternoon.

A pump malfunction resulted in sludge getting into the system at the Lisbon Water Department’s filtration plant, according to a statement issued by the Water Department on Friday night.

Because the Water Department could not confirm that levels of contaminants such as arsenic were safe, the state required it to issue the do not drink order out of precaution, according to the statement.

The Water Department handed out water to people all day Friday.

Results from water samples collected Thursday by DHHS and the Lisbon Water Department showed no elevated arsenic levels, according to a DHHS news release. There were 1 to 3 parts per billion of arsenic detected in the samples; the federal limit is 10 parts per billion.

The Maine Center for Disease Control’s Drinking Water Program is awaiting test results of the level of arsenic in sludge samples it took to determine the level of exposure during the release, according to the news release. The Drinking Water Program expects to have those results back Thursday.

After a customer called to complain about the sludge at 5 a.m. Wednesday, the Water Department isolated the issue and started flushing the water system and continued to flush it until 2 a.m. Thursday morning, according to the Water Department’s Friday night statement.

A valve at the filtration plant was closed to prevent sludge and eliminate the risk of high levels of arsenic from entering the system again, according to the statement.

As of late Friday afternoon, the Maine CDC set up syndromic surveillance but has no evidence of any increase in arsenic poisoning symptoms among those in the community, according to the news release. It will continue to keep in touch with local hospital emergency departments and health care providers over the weekend in case any come up.

Arsenic exposure can cause nausea, vomiting, diarrhea, stomach bleeding, brain swelling, fast or irregular heart rhythms, low blood pressure, unconsciousness or death if ingested in water or food or absorbed through an open wound.

People are encouraged to call poison control at 800-222-1222 if they have any concerns about arsenic exposure. The Water Department encouraged people to seek medical help if they develop any unusual signs or symptoms within 24 hours after consuming water containing high levels of arsenic.