2023 Lead in Drinking Water Sampling Dashboard
o Results are presented in the final data set in both milligrams per liter (mg/L) and parts per billion (ppb).
• Reporting Limit (RL) – This is the limit set by the laboratory that they have 99% confidence in repeatable, accurate and precise results. The majority of results in the table have a RL of 2 ppb (0.002 mg/L). There are some samples that required an additional procedure to be performed by the lab, often due to turbidity (clarity) of the sample, which results in a RL of 1 ppb (0.001 mg/L).
• Method Detection Limit – this is the limit of the method and equipment being used by the laboratory to determine if lead is present in the sample at or above the MDL of 0.66 ppb (0.00066 mg/L).
o U – indicates that lead was not detected above the laboratory RL of 2 ppb (0.002 mg/L).
o J – result was below the laboratory RL of 2 ppb (0.002 mg/L) but above the MDL of 0.66 ppb (0.00066 mg/L). This is considered an estimated value because it is outside the range of confidence the lab requires for results above the RL.
• Facility Location ID – depending on the type of fixture, up to three separate samples could be collected. This field was included in the dataset to help readers determine which samples were collected at the same fixture.
• Sample Types – most fixtures had two samples collected while fountains with internal coolers and some other units required an additional sample:
o Primary Sample (P) – commonly referred to as a first-draw sample, this is the first sample collected after the water has been left stagnant in the system for the required 8-16 hours. This is representative of the conditions present at the beginning of the day or after periods of infrequent use. This sample can help determine if the fixture itself is contributing lead to the water.
o Sequential Sample (S) – This is a sample collected after the primary sample in fixtures, such as water fountains with coolers, to help determine if coolers, storage units or other components are potential sources of lead.
o Flush Sample (F) – This is the last sample collected and helps determine if plumbing leading to a fixture is a potential source of lead.
For Data Prior to 2023 Sampling: Lead In Drinking Water Sampling Results