Table 1.

Microbiological and physical–chemical parameters in water samples collected from the four monochloramine-treated networks.

Water Pipework	Samples Number	Legionella spp. Positives		Physical-Chemical Parameters
		n/Total (%) a	Geometric Mean cfu/L (Range)	Monochloramine Mean ± SD mg/L	T (°C) Mean ± SD	pH Mean ± SD
A	172	4/172 (2.3)	1.3 × 102 (25–2.9 × 103)	2.84 ±1.18	45.3 ± 4.5 b	7.4 ± 0.3
B	136	6/136 (4.4)	7.2 × 10 (25–3.0 × 102)	2.98 ± 1.10	39.1 ± 6.6	7.5 ± 0.4
C	121	1/121 (0.8)	2.5 × 103	2.82 ± 0.95	40.9 ± 5.0	7.4 ± 0.2
E	121	11/121 (9.1)	2.9 × 102 (25–3.2 × 103)	2.93 ± 0.90	40.7 ± 8.1	7.5 ± 0.2
Total	550	22/550 (4.0)	1.9 × 102 (25–3.2 × 103)	2.89 ± 1.05	41.8 ± 6.6	7.4 ± 0.3

SD = Standard Deviation ^a p < 0.005 ^b p < 0.05 A vs. all the other networks.