Hi Diana,
I agree with all the (serious notes) above, and add that the CDC is a great source of info on many human health problems especially infectious ones; here is their link to water contamination.
http://www.cdc.gov/ncidod/diseases/water/drinking.htm
Coliforms can be very serious - one I'm sure you have heard of O157 H7 which can cause renal failure as an end result (but is easily avoided by boiling or chlorinating)
I used to live a few miles away from the site of Canada's worst water borne O157 E.coli outbreak in which 7 died:
http://www.cbc.ca/news/background/walkerton/
The chlorination equipment was neglected and e coli from the cattle of neighboring farms made it into the water supply.
And Harry's photos of crypto and giardia are not without substance, these are real threats as well.
Boil water orders often come from flooding problems where surface water is spilling into wells. Surface water is full of um...nastiness - whereas most well water is usually fairly pristine. If you have not had flooding recently, it could be a chlorination failure (or are they all using
chloramines now?) or as mentioned, a monitoring deficiency.
I have never heard of a farm that is on community water, all my farm experience is those with their own wells, so that is a bit surprising.
We have our own well, and had it tested as M. did, also we were advised as a precaution to shock the well when we first drilled it, with several gallons of chlorine poured straight down the casing.
It should be easy to figure a way to not forget to brush teeth etc - maybe you could lay something over top the faucet so at 1am when you get up to get a drink it will be in your way and make you remember....also move your toothbrush and paste to the kitchen so the abnormal location will remind you that you need to do it differently now.