A suitable sampling regime is required by regulators and these are carried out by utility operators to assess lead risk and the effectiveness of its mitigation through treatment. It is essential that the limitations of any sampling regime are fully appreciated . In the EU random daytime (RDT) sampling has been adopted by many member states as the methodology for assessing lead risk. The random stagnation times associated with RDT sampling introduce a large non-normal variation in the observed lead distribution. Although RDT samples are highly variable and show poor reproducibility large scale studies show that they are representative of the concentrations customers receive through drinking water . While RDT samples are convenient for utilities and customers, their lack of reproducibility causes confusion. Customers expect sample measurements to provide a definitive answer as to whether or not the lead concentrations in their water comply or do not comply with the standard. Unfortunately, the variability of RDT samples is such that little property specific information about lead risk can be concluded from a particular sample result. The value of RDT sample data comes when the data is aggregated.