I believe technically, it should be in the plumbers contract to supply portable toilets on the job site. I remember once working many years ago in a snotty nighborhood, where the homeowner wouldn't let us use there bathroom. There were several trades, plumbers, electricians, carpenters, masons, everyone was there. There must have been at least 20-30 people there. SOmeone asked the homeowner if they could use the bathroom, but the homeowner said no. We had to drive 5-7 miles down the road to use the gas station's rest room. So one morning the lady of the house had to go out to the grocery store. When she was about to leave, she asked the GC to watch her house to make sure that no one used her bathroom. She was gone for about 1-2 hours and no one used her bathroom. They all went in her shrubs, garden, bushes, and everywhere they could find outside all around the house. Nice huh!