water wall
/ˈwɔːtə ˌwɔːl/noun
1A wall which stands alongside water; a containing wall beside or around a body of water. Now rare.
2A vertical sheet of falling water; especially a waterfall. Also: an ornamental wall or sheet of glass down which water continually flows.
3A thin vertical structure in which water is contained or through which it is circulated; specifically (a) one in a boiler, containing pipes through which water to be heated is circulated; (b) one in a building or dwelling, built as an external wall as part of a system of solar heating.
Origin
Late Middle English. From water + wall.