Table 1. Biodiversity indices of the Legionella communities and whole bacterial communities in hot and cold drinking water (values displaying significant differences are given in bold; P-value⩽0.05).

	Legionella community			Bacterial community
	Cold mean (s.d.)	Hot mean (s.d.)	P-value	Cold mean (s.d.)	Hot mean (s.d.)	P-value
Alpha diversitya
Observed species richness	11.00 (±1.37)	10.40 (±2.47)	0.104	18.72 (±1.32)	9.27 (±1.49)	<0.001
Shannon index	2.02 (±0.17)	1.81 (±0.24)	0.009	2.43 (±0.16)	1.56 (±0.14)	<0.001
Simpson index	0.83 (±0.04)	0.77 (±0.05)	0.002	0.88 (±0.03)	0.73 (±0.04)	<0.001
Inverse Simpson index	6.12 (±1.48)	4.62 (±0.97)	0.001	8.88 (±2.09)	3.82 (±0.53)	<0.001
DHill	9.33 (±1.26)	8.33 (±1.99)	0.102	14.68 (±1.50)	6.30 (±0.94)	<0.001
Evennessa
Shannon-based	0.84 (±0.05)	0.78 (±0.06)	0.003	0.83 (±0.05)	0.71 (±0.06)	<0.001
Inverse Simpson-based	0.56 (±0.11)	0.46 (±0.10)	0.008	0.47 (±0.10)	0.42 (±0.07)	0.078
DHill	0.85 (±0.04)	0.80 (±0.05)	0.009	0.78 (±0.05)	0.68 (±0.07)	<0.001
Phylogenetic diversity
Faith's phylogenetic distance (pd)	0.24 (±0.04)	0.19 (±0.05)	0.010	1.34 (±0.12)	1.10 (±0.07)	<0.001
Mean phylogenetic distance (mpd)	0.01 (±0.73)	−0.53 (±0.91)	0.073	−1.11 (±0.75)	1.48 (±0.49)	<0.001
Mean nearest taxon distance (mntd)	0.10 (±0.60)	−0.94 (±0.71)	<0.001	−2.15 (±0.42)	0.77 (±0.52)	<0.001
Beta diversity a
Sørensens index	0.76 (±0.11)	0.66 (±0.11)	<0.001	0.92 (±0.04)	0.84 (±0.07)	<0.001
Jaccard index	0.68 (±0.15)	0.51 (±0.13)	<0.001	0.85 (±0.06)	0.73 (±0.10)	<0.001
Bray-Curtis dissimilarity	0.59 (±0.12)	0.69 (±0.08)	<0.001	0.68 (±0.10)	0.78 (±0.10)	<0.001

^aIndices were calculated for communities of single samples and average values are given; indices for the whole site differ since species accumulate over extended periods of sampling.