What is split sampling and why did EPA include this during the Extended Drinking Water Monitoring Plan?

Split sampling is a technique in which multiple samples are collected from the sample location at the same time but processed and analyzed at different laboratories to compare and confirm results. All split samples are representative of the overall sampling pool and are chosen using a random sampling method to ensure that each sample has an equal unbiased chance of being chosen within the same sampling zone and location type (e.g., residences, priority buildings, hydrants, and shafts).