Table 2.

Change in water lead levels (WLLs) after flushing (vs. FD WLLs) (ppb).

Samples a	N	Median (25%, 75%)	Mean ± SD	Min	Max	90th Percentile	p-Value b
F30S vs. FD	374	0 (−0.4, 0.6)	0.6 ± 4.2	−9.4	50.2	1.7	0.040
F3M vs. FD	372	0 (−0.5, 0.6)	0.2 ± 2.1	−12.5	15.4	2.1	0.219
F6M vs. FD	218	0 (−0.6, 0)	−0.2 ± 1.4	−5.8	7.5	0.7	<0.001
FDH vs. FD	155	−0.1 (−0.9, 0)	−0.4 ± 2.4	−12.9	12.1	0.7	<0.001

^a FD: first draw cold sample; F30S: flushing cold water for 30–45 s; F3M: flushing cold water for 2.5–3 min; F6M: flushing cold water for 5.5–6 min; FDH: first draw hot sample; ^b Compare with FD based on the Wilcoxon signed-rank test.