In reply to Jon Read:
> (In reply to Trangia)
> Somebody had to bring it in, and that's probably exactly how it's sustaining itself: fresh load of susceptible hosts every few days, rapid turnover of host population! If it is norovirus, it can survive in the environment for a few days, but it's the amplifying effect from lots of people continuing to get it (and shed it all over the place) that's probably the main problem.
Correct.
Norovirus is not generally considered to be waterborne, although it may be able to survive in water (likely given that the outbreak at the Fat Duck was linked to oysters harvested from contaminated water). However, if this water gets to the tap untreated, it is likely that it will also be contaminated with other pathogens and there would be recurring illness that would be picked-up through reporting mechanisms.