requirements may still show elevated lead due to the presence of lead and lead- containing plumbing materials and water use patterns. The NJDEP did not originally expect raw water samples to exhibit elevated levels of lead.
Shortly after PWTA sampling began, county and local health agencies noted that some of the reported lead results were unexpectedly high. Often the local health departments, through confirmatory sampling, could not substantiate the results. Well water testing conducted prior to the PWTA rarely detected the presence of lead in well water. Historically, when high levels of lead were found in drinking water it was attributable to
the well structure considers the lead
or plumbing, not groundwater sources.
Therefore, the NJDEP
charts. The raw lead test results indicate tested had lead levels above the old ground
that 5,523 wells water standard of
(11%) out of the 51,028 10 µg/l, and 9,368 (18%)
had lead levels above the of the samples contained
new ground water standard of 5 µg/l. unrealistically high concentrations of
Furthermore, lead with the
highest being 20,200 µg/l. This level is expected to occur in ground water. Based investigations and monitoring of ambient
significantly above any level that would be on the NJDEP’s experience with groundwater groundwater, the homes with water samples
showing elevated lead levels are not near areas where lead is in ground water. It is very unlikely that the source of lead was
likely to be a contaminant the groundwater.
Research conducted in the 1990’s by scientists at NJDEP and Rutgers demonstrated that lead in well water samples collected from homes served by private wells in New Jersey is most likely coming from plumbing. Further, the research shows that the sampling method, sample volume and sampling location are vital in distinguishing between lead in the ground water versus lead coming from the plumbing. As a result of the observed high lead levels in the PWTA database, the NJDEP conducted a study with Rutgers University to more definitively determine the source of the lead.
The sampling procedure used in the study included flushing the house system for five or 10 minutes and collecting the water sample as close to the well head as possible. In most cases, this sampling procedure results in a water sample being collected at the tap at the water tank, not the kitchen sink. The resulting water sample is, in effect, an unflushed sample because the tap at the water tank may not have been opened in years. Although flushing technically occurred, the flushing took place at the kitchen tap, which is not where the water sample was collected.
Information from 10 homes, where extensive water samples were collected and analyzed for lead confirmed this scenario (see Figure 13). The first draw kitchen tap (FD-kitchen) water samples show high lead concentrations. After a five-minute flush,
the lead collected
levels decreased. from the water tank
After the kitchen tap was flushed, water samples were tap, representing a first draw water tank (FD Water Tank)