Green’s Dictionary of Slang

(UK Und.) the lowest, most basic type of lodging house for tramps and beggars.

1873

J. Greenwood In Strange Company 29: The houses which affect the peculiar branch of the lodging business in question are known as ‘hot-water houses’ [...] About twenty in a room is the expected number and they lie in their own rags on the ground [...] The majority of these hot-water lodgers are cadgers and beggars by profession. It is not invariably because they cannot afford it, that they do not patronise the fourpenny houses, but rather they would sooner ‘pig’ together on the boards than lie in separate beds.