The concentration of lead content in drinking water
Older houses use lead pipe plumbing and therefore a higher level of lead content will be detected in the piped water, as compared to newer homes which use PVC pipes.
Lead pipes were used in plumbing until the early 20th century. Houses that are older than 50 years of age might still be using lead pipe plumbing. Many new houses use PVC pipes for plumbing, although copper and galvanized piping is equally popular.
Lead pipes cause the level of lead in tap water to increase substantially. Excessive lead content in drinking water can cause hypertension and kidney problems in adults. It also delays mental and physical growth in children. Regulations in the US require the level of lead in drinking water to be less than 15 parts per billion (ppb).
Do not ingest the water samples.