Ants coming through the cold water pipes through out my house.
I live in the country and have a water well that is under ground with a metal casing around it. When I turn on the cold water I get ants or ant parts in the water. They are also in the tanks of the toilets and clog the filter on the cold water on my washer.
Comment on massplumber2008's post
I would second the above. Do you have a hose bib at your well head to see if they are coming from your submersible? Ants are attracted to electrical current but that is necessarily separate from the water.