Which sampling type occurs at customers' plumbing fixtures?

Lead and copper sampling occurs at customers' plumbing fixtures because it specifically targets the potential contaminants that may leach into the water supply from household plumbing, especially in older homes with lead pipes or plumbing fixtures. This type of sampling is designed to assess the levels of lead and copper in drinking water as it flows through the customer's internal plumbing system. By collecting samples from the fixtures, the analysis can determine whether the water is safe for consumption and if it complies with federal regulations regarding lead and copper levels in drinking water.

In contrast, microbial analysis typically occurs at the source of water supply or at treatment facilities to assess biological contaminants. Disinfection by-products sampling is usually conducted in the distribution system or at treatment facilities to monitor the by-products formed during water treatment disinfection processes, rather than at individual fixtures. Compliance sampling generally refers to a broader testing protocol to ensure the entire water supply meets regulatory standards, which may not specifically focus on individual plumbing fixtures.