Statistical Analysis of Drinking Water Quality and its Impact on Human Health in Chandragiri, near Tirupati, India

By Narasimha Rao C.¹, Dorairaju S. V.², Bujagendra Raju M¹ and Chalapathi P. V.² *
December 2011

Department of Chemical Engineering, Sri Venkateswara University, Tirupati, Andhra Pradesh, India
Department of Chemistry, S. V. Arts Degree and P. G. College, Tirupati, Andhra Pradesh, India * Corresponding Author

Abstract
Drinking water samples were collected from different locations of Chandragiri, near Tirupati, Andhra Pradesh, India and analyzed to assess physicochemical parameters and suitability of water for drinking purpose. Physicochemical parameters such as pH, hardness, alkalinity, calcium, magnesium, iron, nitrates, chlorides, sulphates, electrical conductivity, total solids (TS), total dissolved solids (TDS), total suspended solids (TSS), dissolved oxygen (DO), chemical oxygen demand (COD) and bio chemical oxygen demand (BOD) were determined. The found values were compared with the World Health Organisation water quality standards. Interpretation of data through correlation studies shows that drinking water of some of the areas was polluted and not suitable for drinking purpose. Thus the ground water of these areas needs purification before drinking.

Keywords: Ground Water, Physicochemical Parameters, Alkalinity, Electrical Conductivity, Dissolved Oxygen, Bio Chemical Oxygen Demand

Introduction

Drinking water is one of the most important constituents for healthy living of human society. In India most of the people living in rural areas, depend on ground water for drinking purpose. Ground water is ultimate and most suitable fresh water resource. The quality of water may be described according to its physico-chemical and micro-biological characteristics ¹. The particulate problem in case of water quality monitoring is the complexity associated with analysis of the large number of measured variables². In recent years an easier and simpler approach based on statistical correlation, has been developed using mathematical relationship for comparison of physicochemical parameters^3-6. The physico-chemical analysis of water samples was carried by many researchers using by standard methods ^7-14.
Tirupati is located in the Chittoor district, Andhra Pradesh state, India. Chittoor district lies extreme south of Andhra Pradesh approximately between 12° 37’ – 14° 8’ north latitudes and 78° 3’ – 79° 55’ east longitudes. Most of the people in rural areas of Tirupati depend upon ground water for drinking and other domestic needs. Many pharma, plastic, cement, battery, beverage etc., industries were established in this area. The objective of the present work is to assess the drinking water quality parameters in this area and to study their effect on human health.

Experimental

The study was carried out during the period from June 2010 to June 2011 at Chandragiri area near Tirupati. The drinking water samples were collected in clean and dry polythene bottles. Each sample was filtered using whatmann no.42 filter paper and stored. The water samples collected were analyzed within 5 hours after collection. The temperature of the samples was measured in the field itself at the time of collection. The collected samples were kept in the refrigerator maintained at 4°C and analyzed for a few important parameters in order to have an idea on the quality of drinking water. The average results were presented in table 1 and 2.
Electrical conductivity values were measured using Elico CM 180 conductivity ridge. Total alkalinity was evaluated by titration with standard 0.1M HCl using methyl orange and phenolphthalein as indicators¹⁵. Standard procedures¹⁶ involving spectrophotometry, flame photometry and volumetry were used for the determination of hardness, total dissolved solids (TDS), sulphate, chloride, nitrate, calcium, magnesium iron etc., All the chemicals used were of AR grade.

Results and discussion

pH

The limit of pH value for drinking water is specified¹⁷ as 6.5 to 8.5. PH value in the studied area varied between 6.4-8.4. All the sampling points showed pH values within the prescribed limit by WHO. Abnormal values of pH causes bitter taste to water, affects mucous membrane, causes corrosion and also affests aquatic life.

Hardness

The total hardness is relatively high in all samples due to the presence of calcium, magnesium, chloride and sulphate ions. High amount of hardness in drinking water leads to heart diseases and kidney stone formation¹⁸. Hardness value in the studied area varied between 412-534 mg/L. 6 sampling points showed higher hardness values than the prescribed limit by WHO. Exceeding the permissible limit of hardness causes poor lathering with soap, deterioration of the quality of clothes, scale formation and skin irritation.

Alkalinity

Water with high amount of alkalinity results in unpleasant taste to water and it turns boiled rice to yellowish colour. Various ionic species that contribute to the alkalinity include hydroxide, carbonates, bicarbonates and organic acids. These factors are characteristic sources of water and many natural processes take place at any place¹⁹. Alkalinity value in the studied domestic area varied between 195-561 mg/L. 30 sampling points showed higher alkalinity values than the prescribed limit by WHO.

Calcium

Calcium value in the studied area varied between 56-3014 mg/L. 30 sampling points showed higher calcium values than the limit prescribed by WHO If calcium is present beyond the maximum acceptable limit, it causes incrustation of pipes, poor lathering and deterioration of the quality of clothes.

Magnesium

Magnesium value in the studied area varied between 50-83 mg/L. 39 sampling points showed higher magnesium values than the limit prescribed by WHO. Too high magnesium will adversely affect crop yields as the soils become more alkaline.

Iron

Iron value in the studied area varied between 0.18-0.73 mg/L. 35 sampling points showed higher iron values than the prescribed limit by WHO. The excess amount of iron causes slight toxicity, gives stringent taste to water and can cause staining laundry and porcelain.

Nitrates

Groundwater contains nitrate due to leaching of nitrate with the percolating water and by sewage and other wastes rich in nitrates. Nitrate value in the studied area varied between 3.2-28.4 mg/L. All sampling points showed nitrate values within the prescribed limit by WHO. In the present study, the sampling points in which nitrate has been found to be high, can result in formation of nitroso-amines which are carcinogenic.

Chlorides

Soil porosity and permeability also has a key role in building up the chlorides concentration²⁰. Excessive chloride concentration increase rates of corrosion of metals in the distribution system. This can lead to increased concentration of metals in the supply²¹. Chloride value in the studied area varied between 215-330 mg/L. 27 sampling points showed higher chloride values than the prescribed limit by WHO. The higher values of chloride can cause corrosion and pitting of iron pipes and lates.

Sulphates

Sulphate occurs naturally in water as a result of leaching from gypsum and other common minerals. Sulphate content in drinking water exceeding the 400 mg/L impart bitter taste and may cause gastro-intestine irritation and cantharsis²². Sulphate value in the studied area varied between 145-233 mg/L. 15 sampling points showed higher sulphate values than the prescribed limit by WHO. Ingestion of water with high sulphates cause laxative effect and gastro-intestinal irritation.

Dissolved Oxygen (DO)

DO value in the studied area varied between 2.3-5.9 mg/L. 11 sampling points showed higher DO values higher than the prescribed limit by WHO. High amount of DO imparts good taste to water.

COD

COD in the studied area varied between 8.2-45 mg/L. Water with high COD indicates that there is inadequate oxygen available in the water samples.

BOD

BOD value in the studied area varied between 1.6-3.5 mg/L. All sampling points showed BOD values within the prescribed limit by WHO. Ground water with high value of BOD is due to microbial activities related to the dumpsites.

Conductivity

Electrical conductivity (EC) of water is a direct function of its total dissolved salts²³. Hence it is an index to represent the total concentration of soluble salts in water²⁴. Conductivity value in the studied area varied between 992-2492 µS/cm. 14 sampling points showed higher conductivity than the prescribed limit by WHO. If drinking water has high conductivity, it indicates the presence of high amount of dissolved inorganic substances in ionized form.

Solids

High values of TDS in ground water are generally not harmful to human beings but high concentration of these may affect persons who are suffering from kidney and heart diseases^25,26. A high content of dissolved solids elevates the density of water, influences osmoregulation of fresh water organism, reduces solubility of gases (like oxygen) and reduces utility of water for drinking, irrigation and industrial purposes²⁷. TS, TDS and TSS values in the studied area varied between 331-1192 mg/L, 308-1138 mg/L and 22-152 mg/L respectively. 31 sampling points showed higher TDS values than the prescribed limit by WHO. Continuous comsuption of water with high TDS content can cause gastro-intestinal irritation. It also causes undesirable taste and corrosion or incrustation.

Correlation Studies

Interrelationship studies between different water quality parameters are very helpful in understanding geochemistry of the studied area. The regression equations for the parameters having significant correlation coefficients are useful to estimate the concentration of other constituents. Correlation co efficient values samples are presented in table 3. Alkalinity shows significant correlation with calcium indicating that the alkaline nature of ground water is mainly due to calcium salts. Calcium shows good correlation with chlorides indicating that calcium is associated with chlorides in water of the studied area. Conductivity shows significant correlation with calcium, chlorides and DO which reveals that conductance of water samples is mainly due to calcium and chlorides in the ground water of the studied area.

Conclusions

Over exploitation of resources and improper waste disposal practices affected the drinking water quality. According to WHO, nearly 80% of all the diseases in human beings are caused by water^28,29. Based on the results obtained for physicochemical analysis of ground water samples collected from different locations in the studied Chandragiri area, near Tirupati, it can be concluded that in some samples water quality parameters were beyond the permissible limit prescribed by WHO. Hence, drinking water in the studied area requires precautionary measures before drinking so as to protect human beings from adverse health effects.

Table 1 · Average Results of Chemical Parameters of Ground Water of Athuru, an industrial area near Tirupati
Sampling Point	pH	Hardness (mg/L)	Alkalinity (mg/L)	Ca²⁺ (mg/L)	Mg²⁺ (mg/L)	Fe²⁺ (mg/L)	NO₃^- (mg/L)	Cl^- (mg/L)	SO₄^2- (mg/L)
S 1	6.6	420	214	73	53	0.44	8.2	247	177
S 2	6.8	428	285	107	57	0.64	13.5	252	170
S 3	7.8	436	403	155	58	0.41	13.1	263	152
S 4	7.6	472	499	145	59	0.53	11.6	260	233
S 5	6.8	534	368	118	62	0.59	16.4	254	151
S 6	8.3	490	500	300	65	0.25	15.6	291	191
S 7	8.1	412	387	178	76	0.44	4.6	271	163
S 8	7.7	516	505	150	80	0.45	25.9	262	183
S 9	8	505	524	173	59	0.39	14.2	269	146
S 10	6.4	430	226	61	51	0.5	7.1	231	180
S 11	6.5	429	215	68	50	0.5	19.4	240	171
S 12	6.4	428	216	59	57	0.63	16.3	230	219
S 13	6.6	442	397	99	60	0.73	18	251	155
S 14	6.7	443	348	105	66	0.54	5.4	252	166
S 15	6.4	431	195	64	50	0.47	14	235	199
S 16	6.5	419	212	65	57	0.52	17.3	238	217
S 17	8.1	461	418	185	64	0.33	3.9	279	196
S 18	7.8	513	471	158	66	0.29	19.5	263	187
S 19	7.9	527	512	160	69	0.47	4.6	266	163
S 20	8.2	506	491	254	67	0.38	15.5	285	189
S 21	8.3	456	298	275	73	0.46	28.4	289	184
S 22	8.3	483	501	287	68	0.34	3.4	289	184
S 23	8.1	488	561	189	71	0.31	27.2	282	171
S 24	8.2	451	359	200	77	0.27	15.6	283	145
S 25	6.9	442	352	118	63	0.53	15.1	257	168
S 26	6.5	434	225	70	54	0.43	16.3	241	172
S 27	6.8	446	310	108	68	0.51	15.4	252	180
S 28	6.5	437	219	72	57	0.36	4.6	243	198
S 29	7.3	460	279	143	60	0.45	3.4	260	191
S 30	6.9	451	482	125	65	0.34	3.8	259	172
S 31	7	434	410	125	70	0.59	16	259	180
S 32	7.1	453	413	140	70	0.23	7.5	260	181
S 33	8.4	472	541	301	79	0.33	11.4	330	223
S 34	8	431	373	170	68	0.4	27.5	266	178
S 35	6.6	430	444	87	64	0.18	9.5	247	180
S 36	6.4	412	277	56	56	0.4	3.2	215	192
S 37	6.6	434	210	88	58	0.5	7.7	250	171
S 38	8.1	416	378	178	83	0.42	13.4	273	178
S 39	6.4	434	199	62	58	0.52	25.4	234	218
S 40	6.5	469	296	185	63	0.37	16.8	221	194
WHO	6.5-8.5	500	250	75	50	0.3	45	250	200

Table 2 · Average Results of Physical and Biological Parameters of Ground Water of Athuru, an industrial area near Tirupati
Sampling Point	Physical Parameters					Biological Parameters
Sampling Point	Temp (°C)	Conductivity (µS/cm)	Total Solids (TS) (mg/L)	Total Dissolved Solids (TDS) (mg/L)	Total Suspended Solids (TSS) (mg/L)	Dissolved Oxygen (DO) (mg/L)	Chemical Oxygen Demand (COD) (mg/L)	Biochemical Oxygen Demand(BOD) (mg/L)
S 1	31	1333	422	394	28	5.3	14.1	2
S 2	31.2	1418	431	393	38	4.5	8.2	2.1
S 3	30.6	1624	884	830	54	4	28	2.9
S 4	32	1520	888	847	41	4.1	27.9	2.4
S 5	31.8	1434	924	891	33	4.5	25.2	2.2
S 6	31.5	2292	1051	984	67	2.5	10.2	3.4
S 7	31.6	1924	489	443	46	3.4	9.9	3
S 8	31	1616	528	452	76	4	17.7	2.9
S 9	31.5	1896	582	524	58	3.4	12.3	3
S 10	31.4	1254	1148	1107	41	5.7	34	1.7
S 11	31.8	1288	1045	1002	43	5.5	33.5	2
S 12	32	1186	971	931	40	5.8	34.7	1.6
S 13	31.9	1356	880	832	48	4.8	12.9	2.1
S 14	30.7	1408	1063	1013	50	4.6	19.5	2.1
S 15	30.7	1259	891	846	45	5.6	42.1	1.8
S 16	31.5	1281	1073	1002	71	5.5	24.5	1.9
S 17	31.8	1984	1060	1003	57	3.3	27.8	3.1
S 18	31.6	1816	507	414	93	3.6	18	2.9
S 19	31.8	1836	426	377	49	3.5	10.3	3
S 20	31.5	2038	923	857	66	3	15.3	3.3
S 21	31	2075	959	893	66	3	12.9	3.3
S 22	30.9	2137	1190	1104	86	2.8	11.8	3.3
S 23	30.9	2012	775	697	78	3.3	16	3.2
S 24	31.2	2034	875	816	59	3.3	13.2	3.2
S 25	30.7	1440	852	806	46	4.4	14.8	2.3
S 26	32.3	1310	1192	1138	54	5.5	44.4	2
S 27	32.3	1429	774	731	43	4.5	22	2.2
S 28	30.8	1326	820	767	53	5.4	43	2
S 29	31.7	1515	412	341	71	4.1	14.4	2.4
S 30	30.9	1444	877	839	38	4.4	28	2.3
S 31	32.1	1454	331	308	23	4.3	20.8	2.4
S 32	31.3	1460	999	944	55	4.2	13.9	2.4
S 33	31.2	2492	744	710	34	2.3	12.9	3.5
S 34	31.4	1876	869	794	75	3.5	14.1	3
S 35	32	1340	978	902	76	5.3	45	2
S 36	32.7	992	504	482	22	5.9	44	1.6
S 37	32	1356	748	717	31	5	23.2	2.1
S 38	31.4	1970	955	902	53	3.4	18	3
S 39	32.8	1255	644	597	47	5.6	36.8	1.8
S 40	32.1	1528	849	697	152	4	17.2	2.8
WHO	30.0	1800		500		5.0		6.0

Table 3 · Correlation Coefficient Values of various Physico-Chemical Parameters of Ground Water of Athuru, an industrial area near Tirupati
	pH	TH	TA	Ca²⁺	Mg²⁺	Fe²⁺	NO₃^-	Cl^-	SO₄^2-	DO	COD	BOD	Temp	Cond	TS	TDS	TSS
pH	1
TH	0.4835	1
TA	0.73317	0.66123	1
Ca²⁺	0.8884	0.50873	0.67989	1
Mg²⁺	0.70262	0.30377	0.61372	0.65857	1
Fe²⁺	-0.4485	-0.208	-0.4151	-0.4558	-0.3306	1
NO₃^-	0.124	0.15951	0.0126	0.11112	0.1595	0.1555	1
Cl^-	0.88574	0.43211	0.69877	0.87233	0.68541	-0.3847	0.06996	1
SO₄^2-	-0.1172	-0.1217	-0.1525	-0.0087	-0.1154	-0.0152	0.03311	-0.07	1
DO	-0.9396	-0.5517	-0.7625	-0.9541	-0.7325	0.41862	-0.101	-0.8944	0.13603	1
COD	-0.6204	-0.3817	-0.483	-0.6465	-0.5579	0.00179	-0.1167	-0.6138	0.30655	0.74159	1
BOD	0.95116	0.54133	0.72896	0.93933	0.72054	-0.4905	0.17637	0.86212	-0.1561	-0.9728	-0.6678	1
Temp	-0.3171	-0.0883	-0.2162	-0.2902	-0.1907	0.192	0.04497	-0.3923	0.24676	0.30919	0.3186	-0.3193	1
Cond	0.94454	0.48011	0.68622	0.94543	0.69288	-0.4762	0.13432	0.92656	-0.066	-0.9576	-0.6381	0.96102	-0.3178	1
TS	-0.0423	-0.102	-0.0893	0.08909	-0.127	-0.1583	0.03496	0.02706	0.09417	0.04565	0.28822	-0.0191	-0.1529	0.04924	1
TDS	-0.0665	-0.1357	-0.1112	0.05288	-0.1495	-0.1185	0.00781	0.02247	0.08892	0.07986	0.31367	-0.0607	-0.1473	0.01995	0.99529	1
TSS	0.23966	0.32822	0.21044	0.37931	0.21082	-0.4254	0.28	0.05029	0.06602	-0.3406	-0.2187	0.41857	-0.0777	0.30372	0.18442	0.08827	-0.0777

TH= Total Hardness, TA= Total Alkalinity, DO=Dissolved Oxyen, COD=Chemical Oxyen Demand, BOD=Biochemical Oxyen Demand, Temp=Temperature, Cond=Conductivity, TS=Total Solids, TDS=Total Dissolved Solids, TSS=Total Suspended Solids
All the parameters measured as mg/L except Temperature (°C) and Conductivity (µS/cm)

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