Table 2 Heavy metal content in different water sources.

Heavy metal (mg/L)	Spring water	Treated wastewater	Normal water	Standard limit (mg/L)
Lead (Pb)	0.005 ± 0.001^b	0.008 ± 0.001^a	0.003 ± 0.001^c	0.01
Cadmium (Cd)	0.002 ± 0.0005^b	0.004 ± 0.0007^a	0.001 ± 0.0006^c	0.005
Mercury (Hg)	0.0005 ± 0.0001^c	0.0008 ± 0.0002^a	0.0006 ± 0.0002^b	0.001
Nickel (Ni)	0.01 ± 0.002^c	0.015 ± 0.003^a	0.012 ± 0.002^b	0.02
Zinc (Zn)	0.20 ± 0.01^c	0.50 ± 0.03^a	0.30 ± 0.02^b	3.0
Arsenic (As)	0.001 ± 0.0002^c	0.002 ± 0.0003^a	0.0015 ± 0.0002^b	0.01
Chromium (Cr)	0.02 ± 0.003^c	0.03 ± 0.005^a	0.025 ± 0.004^b	0.05
Copper (Cu)	0.10 ± 0.01^c	0.20 ± 0.02^a	0.15 ± 0.015^b	2.0
Manganese (Mn)	0.05 ± 0.005^c	0.08 ± 0.007^a	0.06 ± 0.006^b	0.4
Iron (Fe)	0.10 ± 0.02^c	0.30 ± 0.05^a	0.20 ± 0.03^b	0.3
Cobalt (Co)	0.005 ± 0.001^c	0.01 ± 0.002^a	0.008 ± 0.0015^b	0.05
Selenium (Se)	0.002 ± 0.0005^c	0.004 ± 0.0008^a	0.003 ± 0.0006^b	0.01

Values are expressed as mean ± standard deviation (n = 3).
^a–cDifferent superscript letters represent significant differences within the row (p < 0.05). Permissible limits based on FAO/WHO guidelines for edible olive oil.

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