Worried by the poor sanitation, inefficiency, and high cost of bathrooms, Bucky came up with a solution in 1936.
The four, stamped sheet metal or molded plastic sections are each light enough to be carried by two workers. They'll fit up tight staircases and through narrow doors, allowing retrofitting in existing structures. All the appliances, pipes, and wires are built-in, limiting on-site construction to mere hook-up.
With the sections bolted together, the interior has no germ-harboring nooks, crannies, grout cracks or anything that can rot. Large-radius corners make germicidal swabbing easy and complete. Downdraft ventilation draws fumes and steam to the undersink vent. Both sink and (deep) bath-shower are arranged to ease the care of children and seniors. The mirror doesn't steam up, the sink doesn't splatter, and the toilet paper stays dry.
Dymaxion Bathrooms are to be equipped with "Fog Gun" hot water vapor showers that use only a cup of water to clean hygienically without soap. Remarking that "Nature had designed humans to separate urine and excrement. Both are valuable chemistry, and should be collected for further use," Bucky specified a waterless "Packaging Toilet" that deftly shrink-wrapped the stuff for pickup for later composting. (Ordinary toilets use approximately 2000 gallons of pure drinking water per year to flush - and waste - one human's "exhaust" that, if dried out, would scarcely fill two 5-gallon pails.)