Rainwater supply systems use Section 2 materials and Section 5 installation, rainwater pipework is marked RAINWATER at set intervals and outlets labelled or fitted with a green RW indicator, and where rainwater and utility supplies connect the utility supply is protected by a backflow device, flushing supplies are protected and a check valve stops utility water entering the tank; mains top-up of tanks has backflow protection chosen by tank location (2003 Section 14).
The graph holds this control, the 0 it maps to, and the evidence behind each claim, over MCP and REST.