IWA Publishing

Table 1

Summary of the physical, chemical and microbiological parameters of wells in Vegas-Las Palmas parcels, Sixaola

Parameter	Units	Average	SD	Min	Max	WHO	CR
Temperature	°C	25.5	2.6	19.9	33.9	–	30
pH	–	6.45	0.32	5.50	7.29	6.5–9.5	6–8
Conductivity	μS/cm	289	151	102	670	–	400
Turbidity	NTU	4.67	9.37	0.00	58.30	–	5
TDS	mg/L	205	92	80	460	1,200	1,000
Hardness	mg/L CaCO₃	133	81	12	380	–	400
Fluoride^a	mg/L	0.123	0.061	<0.056	0.456	1.5	0.7
Chloride	mg/L	16.65	16.54	2.94	77.90	250	250
Nitrate^a	mg/L	8.76	14.39	<0.402	27.70	50	50
Sulphate	mg/L	16.69	24.37	0.76	145.80	500	250
Ca²⁺	mg/L	35.2	23.2	4.5	111.0	–	100
K⁺	mg/L	1.98	2.17	0.20	14.00	–	10
Na⁺	mg/L	14.7	7.3	0.7	38.4	200	200
Mg²⁺	mg/L	8.8	8.7	0.1	61.0	–	50
Zn^a	mg/L	0.061	0.085	<0.04	0.223	2	3
Fe^b	mg/L	–	–	<0.3	4.82	–	0.3
Mn^b	mg/L	–	–	<0.5	3.66	0.4	0.5
Cu^b	mg/L	–	–	–	<0.3	2	2
Cd^b	mg/L	–	–	<0.040	0.113	0.03	0.003
Pb^b	μg/L	–	–	<4	17	10	10
Cr^b	μg/L	–	–	–	<4	50	50
As^b	μg/L	–	–	–	<0.5	10	10
Total coliform	MPN/100 mL	3.1 × 10⁴	6.9 × 10³	2	4.6 × 10⁴	–	–
Faecal coliform	MPN/100 mL	3.0 × 10⁴	7.0 × 10³	2	4.6 × 10⁴	0	0
Escherichia coli	MPN/100 mL	1.1 × 10³	2.0 × 10³	2	10⁴	0	0

Parameter	Units	Average	SD	Min	Max	WHO	CR
Temperature	°C	25.5	2.6	19.9	33.9	–	30
pH	–	6.45	0.32	5.50	7.29	6.5–9.5	6–8
Conductivity	μS/cm	289	151	102	670	–	400
Turbidity	NTU	4.67	9.37	0.00	58.30	–	5
TDS	mg/L	205	92	80	460	1,200	1,000
Hardness	mg/L CaCO₃	133	81	12	380	–	400
Fluoride^a	mg/L	0.123	0.061	<0.056	0.456	1.5	0.7
Chloride	mg/L	16.65	16.54	2.94	77.90	250	250
Nitrate^a	mg/L	8.76	14.39	<0.402	27.70	50	50
Sulphate	mg/L	16.69	24.37	0.76	145.80	500	250
Ca²⁺	mg/L	35.2	23.2	4.5	111.0	–	100
K⁺	mg/L	1.98	2.17	0.20	14.00	–	10
Na⁺	mg/L	14.7	7.3	0.7	38.4	200	200
Mg²⁺	mg/L	8.8	8.7	0.1	61.0	–	50
Zn^a	mg/L	0.061	0.085	<0.04	0.223	2	3
Fe^b	mg/L	–	–	<0.3	4.82	–	0.3
Mn^b	mg/L	–	–	<0.5	3.66	0.4	0.5
Cu^b	mg/L	–	–	–	<0.3	2	2
Cd^b	mg/L	–	–	<0.040	0.113	0.03	0.003
Pb^b	μg/L	–	–	<4	17	10	10
Cr^b	μg/L	–	–	–	<4	50	50
As^b	μg/L	–	–	–	<0.5	10	10
Total coliform	MPN/100 mL	3.1 × 10⁴	6.9 × 10³	2	4.6 × 10⁴	–	–
Faecal coliform	MPN/100 mL	3.0 × 10⁴	7.0 × 10³	2	4.6 × 10⁴	0	0
Escherichia coli	MPN/100 mL	1.1 × 10³	2.0 × 10³	2	10⁴	0	0

TDS, total dissolved solids; SD, standard deviation; WHO, World Health Organization; CR, Costa Rican legislation.

^aCalculated using maximum likelihood estimation method.

^b > 80% censored data.