There must be secondary containment, bunding for example, to hold any leak from the closed system. Its capacity must cover (a) the fluid volume of the largest single container, or of a group of containers where interconnection could let several leak at once, plus (b) whatever volume of disinfectant may be used, with extra capacity so that expected general fluid movement does not breach it.
The graph holds this control, the 0 it maps to, and the evidence behind each claim, over MCP and REST.