NORTH BATTLEFORD, Sask. -- Residents of the Saskatchewan city of North Battleford must still boil their drinking water while officials wait for more test results.

Authorities had hoped a precautionary drinking-water advisory would be lifted by the weekend.

City manager Jim Puffalt said final tests were completed Sunday and delivered to a lab in Saskatoon. The Saskatchewan Water Security Agency is expected to have the results Tuesday and could end the advisory the same day.

There have been no reported illnesses, Puffalt said, and previous tests have shown no water-borne parasites.

"The additional testing required we were doing last week already --and those all showed negative -- so we don't expect that we'll find anything untoward in the water," he said Monday.

"Certainly it's a little bit longer than we would have liked ... but we just can't take any chances with people's health."

A "process error" last Tuesday led to about 8,000 litres of partially treated water going into clean water at one of the city's filtration plants for six minutes. The facility was shut down and its main lines were flushed.

Puffalt said engineers believe the partially treated water remained in the treatment plant, but officials issued the advisory as a precaution.

The city's 14,000 residents have been told to boil all water used for drinking, cooking and brushing teeth for at least one minute.

More than 7,000 residents became sick in 2001 when a parasite called cryptosporidium entered the city's water supply during routine maintenance of a chemical filter.

No one died.