Table 2.

Disinfectant residual concentration and microorganism recovery and detection frequency summary by system and sample location

System	Sample Location	Disinfectant Residual			Microorganisms
		Total Cl₂ Avg ± SD (mg Cl₂/L)	NH₂Cl Avg ± SD (mg Cl₂/L)	$\frac{{NH}_{2} Cl}{{Total Cl}_{2}}$ (%)	HPC Culture No. Samples Positive	NTM Culture No. Samples Positive	MAb Culture [qPCR] No. Samples Positive	MI Culture [qPCR] No. Samples Positive	MA [qPCR] No. Samples Positive
SW1	EP	3.7 ± 0.5	3.2 ± 0.3	86	1	4	[1]
	ART	1.7 ± 0.8	1.3 ± 0.7	76	4	4	[4]	[2]
	TANK	1.8 ± 0.4	1.6 ± 0.7	89	4	4	1 [4]	[1]
	MRT	0.9 ± 0.4	0.7 ± 0.3	78	4	4	[4]	[1]
SW2	EP	3.9 ± 0.2	3.3 ± 0.2	85	2	3		1 [3]
	ART	2.7 ± 0.2	2.2 ± 0.2	81	3	4	[4]	[1]
	TANK	2.1 ± 0.3	1.7 ± 0.2	81	4	4	[4]	1 [4]	[1]
	MRT	1.4 ± 0.3	0.8 ± 0.8	57	4	4	[4]	[3]
SW3	EP	3.5 ± 0.4	2.9 ± 1.3	83	2	4	[2]	[2]
	ART	1.4 ± 0.6	1.0 ± 0.3	71	2	4	[2]	1 [4]
	TANK	1.1 ± 0.5	0.7 ± 0.3	64	4	4	2 [1]	[4]
	MRT	1.2 ± 0.7	0.7 ± 0.5	58	3	4	[3]	[3]
GW	EP	5.4 ± 0.9	4.4 ± 0.6	81	1	3
	ART1	1.7 ± 1.7	0.9 ± 0.8	53	4	3	[1]
	ART2	3.4 ± 0.8	2.6 ± 0.9	76	0	1	[1]	[3]
	MRT	3.3 ± 0.9	2.2 ± 1.0	67	1	1	[1]

SW – Surface Water; GW – Groundwater; Monochloramine -NH₂CL; HPC - heterotrophic plate counts; NTM – nontuberculous mycobacterium, MAb - M. abscessus, MI -M. intracellulare, and MA – M. avium, ART – average residence time sample; EP – entry point sample; GAC – granular activated carbon; MRT – maximum residence time sample