<Ol> <Li> Community Water System (CWS). A PWS that supplies water to the same population year - round . </Li> <Li> Non-Transient Non-Community Water System (NTNCWS). A PWS that regularly supplies water to at least 25 of the same people at least six months per year, but not year - round . Some examples are schools, factories, office buildings, and hospitals which have their own water systems . </Li> <Li> Transient Non-Community Water System (TNCWS). A PWS that provides water in a place such as a gas station or campground where people do not remain for long periods of time . </Li> </Ol> <Li> Community Water System (CWS). A PWS that supplies water to the same population year - round . </Li> <Li> Non-Transient Non-Community Water System (NTNCWS). A PWS that regularly supplies water to at least 25 of the same people at least six months per year, but not year - round . Some examples are schools, factories, office buildings, and hospitals which have their own water systems . </Li> <Li> Transient Non-Community Water System (TNCWS). A PWS that provides water in a place such as a gas station or campground where people do not remain for long periods of time . </Li>

Where did a city of the middle ages obtain drinking water