Natick’s Department of Public Works issued an alert to residents on Wednesday that they should boil water for at least a minute before consuming it in light of E. coli bacteria being discovered in drinking water samples collected on Jan. 12.

The issue also affects around 80 homes in Wellesley. The Town of Wellesley’s Department of Public Works warns that “This order DOES AFFECT some Wellesley residential addresses that receive water service from Natick, although you pay a Town of Wellesley utility bill. You may not be aware that your water is actually provided by Natick.”

Water should also be boiled before using it in food preparation, brushing teeth, and washing dishes, or use bottled water. E. coli bacteria can make you ill, and is a particular concern for those with weakened immune systems.

This warning applies until further notice.

According to the state’s Department of Environmental Protection, “Pets:The same precautions to protect humans apply to pets. Do not expose aquatic organisms (e.g., fish) to water containing elevated bacteria levels. If you need to refresh the organism’s water, use appropriately boiled or bottled water.”

Natick has removed water sources that tested positive and has increased water disinfection treatments.

“The town hopes to resolve this inconvenience within the next few days,” according to a Natick recording.

When the Massachusetts Department of Environmental Protection issues a public health order, public water suppliers are required to notify customers.