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If lead is found in drinking water, it is important to identify where it is coming from within the water system–that means taking samples at every stage, from the distribution system all the way to the plumbing system inside the home, also known as premise plumbing.
There are many types of sampling techniques available to assess the presence of lead in drinking water. Deciding which one to use depends on what the objective is. Different sampling tools can be used to assess lead exposure, evaluate corrosion treatment effectiveness for different plumbing materials, or identify particularly significant lead contributors that can be removed to mitigate the problem.
A water utility may implement regulatory sampling protocols to meet a trigger or standard – the level above which the water system must take an action. Regulatory sampling isn’t meant to diagnose lead sources or assess the risk of lead exposure in an individual residence. However, many utilities do sample drinking water for lead beyond the regulatory requirements to better help identify sources of lead, improve corrosion control treatment, and to inform the public of their risk of exposure.
EPA researchers have identified several sampling protocols to help water utilities assess and mitigate the risk of lead exposure. These techniques fall under two categories–diagnostic water sampling and exposure sampling.