Table 2.

Sampling Methods for Once Through Flow Events

Method	Description	Volume sampled	Pros/Cons	Likelihood to detect soluble and particulate lead
First draw & profiling	Collect first amount of water during flushing and subsequent samples	1–2 L or extent of profile	Quantifies all lead in samples collected, very sensitive to flow rate, and likelihood of missing spikes	Detects all Pb in water (particulate and soluble) collected but can miss sporadic spikes
Grab samples	Collect small samples periodically	10 mL	Provides profile of soluble lead, does not sample large portion of flow event, and sensitive to flow	Detects soluble lead, may miss particulate spikes
Proportional sampler	Splits flow such that a portion is collected for analysis	A fraction of daily flow	Conventional designs “miss” particulates. Other designs could concentrate particulates.	Depends on design
Bins to collect all water from pipe rigs	Collects all water during a daily flush	Entire daily	Collects all water and quantifies suspended fraction, including spikes but not practical	Confined to laboratory. Likely to detect all Pb (particulate and soluble)
Whole-house filters	Filters lead from all water for an extended period of time	Entire	Samples large volumes with minimal effort. Misses soluble and small colloidal lead.	Potentially quantifies a large fraction of particulates Pb > 1 μm