Why’s it called ‘condominial’ sewerage?

Why do Brazilians call simplified sewerage ‘condominial’ sewerage? [They actually use both terms: redes de esgotos simplificadas and esgotamento condominial – rede means network, esgotos means sewage and esgotamento sewerage.] The explanation given on page 55 of The Last Taboo (see today’s other blog), that it’s because “instead of laying a sewer in the road and connecting every house on an individual basis, the pipe runs from one house or dwelling to another as if they were in an apartment block”, is not quite correct (almost, but not quite). It was explained to me many years ago by Professor Cícero Onofre Neto of the Universidade Federal do Rio Grande do Norte as follows: see how on the outside of a condominium (used in the American sense of a block of privately owned apartments sharing the costs of common services) the main drainage pipe is vertical and each apartment is connected to this by an inclined pipe, so that it looks like a series of vertically joined Y’s; now rotate this pipework through 90° away from the condominium wall, and you have the horizontal version which is used in ‘backyard’ or in-block simplified sewerage (the original layout for simplified sewerage in northeast Brazil) with each house connected individually to the sewer. Just thought I’d set the record straight (especially for those who think simplified sewerage and condominial sewerage are different).