Portuguese to English Other Architecture

Does "caixa acoplada means "flush tank" in the context below?? I am not real sure if this is what they mean.

Thanks a lot!


OBS: BACIA SANITÁRIA NO CONTEXTO ABAIXO É "VASO SANITÁRIO".



HERE'S THE CONTEXT (some sentences have already been translated):


PROCEDURES FOR THE DEVELOPMENT OF THE HYDRAULIC PROJECT


1.2 -Definition of the Systems to be designed:

Cold water, hot water, fire (hydrants, sprinklers, etc), sanitary sewage, pluvial waters, gas, others.

1.3 -Definição da utilização do tipo de bacia sanitária a ser utilizada com **caixa acoplada** ou válvula de descarga.