Yup,and when your water bill comes you may realize a few thousand gallons of public water went into the well.
You are suppose to have backflow prevention for the oppisite serinerio,maybe you should have one for both ways.

Agree with Klem, while you're working on the pump would be a good time to add a check valve.

Ev

Yes, I'm going to add a check valve to prevent that from happening again. I have a check valve in the public water line, I just never got around to adding one on the well.

I checked my water meter Klem, It appears that my foot valve is in good condition, I only used/lost 200 gallons, I've got 800 more gallons before I have to pay any extra!