I cycle to work, and it means that I take a shower in the morning at the office building, and another one in the evening back home. So one shower per day is included in the domestic consumption (for me, and for others who don't cycle but also take a daily shower at home).

I don't think that's so different between U.S., Copenhagen or my place (Finland). It might be different in less modernist cultures where people don't have bathrooms of their own but go to communal baths -- for example, communities in East Karelia/Russia; there many people just bath twice a week in a public баня and that would surely show up in water consumption per person when measured per apartment. On the other hand, there you probably will see that water is not priced at cost and many many taps will leak a lot...