NSF International The Public Health and Safety Company ™ NSF/ANSI Standard 53 Lead pH 8.5 Testing Update Live Safer™

Protocol Origins Current Lead pH 8.5 protocol adopted in 2007. Laboratories conducting tests under old protocol were internally consistent, but inconsistent between laboratories. Particulate lead was determined to be the primary cause of the inconsistency. Literature search was performed to establish levels of particulate in distribution systems. Two validation studies were conducted by many laboratories to develop and finalize protocol.

Occurrence of Particulate Lead Literature search was conducted with the goal of obtaining references that would clarify the existence of particulate lead and provide data to guide the Task Group in setting an influent requirement. 28 citations were found that contained relevant information about the formation and presence of particulate lead in public water supplies. 7 citations contained field data on the occurrence of particulate lead in real world water distribution systems.

Occurrence of Particulate Lead No references were found that refuted the presence of particulate lead in drinking water systems. Particulate lead was found in many different water chemistries, low and high pH. Levels measured varied significantly based on when and how a sample was collected. Size distribution varied significantly between samples.

Field Data – Ratio of Particulate to Total Lead Lead Form Mean Std Dev 90th Percentile Total Lead (ppb) 28 67 89 Particulate Lead (ppb) 21 61 68 Percent Particulate Lead 59 35 100 Data set consists of 101 data points reported from 5 references. Some data points are averages of several samples taken in a study (over 200 individual samples). Data represents 22 different distribution systems (10 from UK, 12 from USA)

Field Data – Variation due to Sample Conditions Initial Conditions Stable Conditions Test Condition Total Lead (ppb) Particulate Lead (ppb) Rapid Valve 1800 1600 12 7 Slow Valve 670 500 4 0.5 Low Flow 1300 1100 10 2 High Flow 4500 4300 5 Lead Service Line from New Orleans, LA.

Field Data – Variation from Single Source Lead Size Range Average Percent Std Dev Upper 90th Percentile Lower 90th Percentile > 1 um 49 26 94 18 < 1 um 51 82 6 Data from 31 samples collected from one water source. Range of measurements were 0 to 100%. Range of percent of lead particulate from 0 to 93% of total lead.

NSF Lead pH 8.5 Water Preparation Average Total Particulate is 34%. 86% of Total Particulate values fall within the 20 – 40% range (average range required in Std). Average Fine Particulate is 68%. 86% of all tanks prepared meet Standard requirements. Primary reasons for missing water preparation requirements are: 1. Equipment requires cleaning 2. Technician error

Recommendations for Lead Protocol Improvement The filtration of the sample to determine fine particulate must be performed at a rate that exceeds 1ml/second. Otherwise fine particulate values are under reported. Explicit instructions on adjusting soluble and insoluble additions to hit challenge targets. Additional language urging the need to follow all requirements precisely, including listing some of the critical elements.

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