Table 1.

Median values of microbial indicators defined in D. Lgs 31/01

Microbial parameters	Karst-fissured aquifers (No. wells)						Porous aquifers (No. wells)				p value
	Gargano (21)		Salento (47)		Murgia (75)		Tavoliere (44)		Arco Jonico (20)
	Median	Range	Median	Range	Median	Range	Median	Range	Median	Range
Compulsory*
Total coliform	30	0–1500	0	0–6000	0	0–2000	20	0–2000	16	0–6000	0.0014
Escherichia coli	2	0–800	0	0–3000	0	0–1800	0	0–900	0	0–1600	0.0014
Enterococci	3	0–500	0	0–900	0	0–800	1	0–500	0	0–600	0.0014
Optional**
Salmonella spp	0	0–0	0	0–120	0	0–20	0	0–7	0	0–8	0.124
P. aeruginosa	0	0–800	0	0–3000	0	0–900	0	0–2000	0	0–600	0.06
HPC 22 °C	50	0–900	2	0–3000	3	0–22,000	50	0–6000	20	0–2300	0.0014
HPC 37 °C	25	0–700	0	0–3000	0	0–20,000	20	0–8000	9	0–2000	0.0014

*Total coliform, Escherichia coli and Enterococci (CFU/100 ml); **Salmonella spp. (CFU/L), P. aeruginosa (CFU/250 ml), and HPC (CFU/ml)