The first way to deal with leftover spray mix and tank washings is to apply them to the crop, as long as the total label dose is not exceeded; anything left over after that is disposed of so the environment is not put at risk. Wastewater containing agrochemicals is never discharged into the open environment, and disposal is recorded.
The graph holds this control, the 0 it maps to, and the evidence behind each claim, over MCP and REST.