>>1123Rivers
Someone's lawn taps and hose, when they're not at home of course
Camping shower
Wet wipes
Mall toilets (can easily wash hair in a handicapped bathroom, no one will bother you)
Public baths (a common thing in some countries, same as gym)
Though, public baths (onsen, sauna) have an advantage over standard showers: you can get full soaking and scrub yourself thoroughly, plus they cost less than one-time gym visits since not all gyms have all-country franchise chain coverage.