@Hex If not working remotely, it's a health and safety breach if your working conditions do not have working toilet facilities.
Plaster of Paris should never be put down toilets or sinks, it hardens very quickly and causes blockages that can require expensive plumbing. If some amount of it is put down a sink or toilet at the end of a business day on a Friday, there is no doubt that Monday and Tuesday the working conditions would not be fit.
Health and safety is important.