Lead and copper samples should be taken from which of the following?

Lead and copper samples should be taken from point of use sites, specifically plumbing fixtures, because these locations are where the water comes into contact with plumbing materials that may leach lead and copper into the water supply. Sampling at these points ensures that the measurements reflect the actual water quality that consumers experience at their taps, which is influenced by both the quality of the water and the condition of the plumbing infrastructure.

Point of entry locations and water treatment plants primarily measure the water quality before it enters the distribution system or before consumers access it, which does not provide an accurate representation of lead and copper levels that are influenced by the plumbing system. While public fountains and water stations may deliver water directly to the public, they are not the optimal choice for monitoring lead and copper levels from household plumbing and fixtures where accumulation can occur.