Chinmaya Kumar Behera

Chapter 3 Water-Suitability 3.1 Introduction It is well known that water is used for innumerable purposes. The primary uses of water include its usage in the agriculture and industrial sectors. Water usage (water quality) for different purposes depends on a number of factors/parameters. Water usage for a particular cause can be judged based on either a single constituent or multiple constituents. Also, many parameters can be computed to know the suitability of water. Apart from these, few graphical methods can also be employed for the purpose of deciphering the suitability of water. In this chapter, the suitability of water of the study area for agricultural, industrial and drinking purposes has been investigated and the results presented in the following paragraphs; 3.2 Suitability for agricultural purpose As already mentioned above, different methods can be employed for deciphering the suitability of water. For the purpose of agricultural usage (irrigation), graphical methods and computation of some parameters have been attempted here. 3.2.1 Wilcox’s classification Wilcox (1948) proposed a method for evaluating the quality of waters to be used for irrigational purposes, based on electrical conductivity and percent sodium (Na%). The Wilcox’s diagram consists of five distinct divisions viz. i) Excellent to Good, ii) Good to Permissible, iii) Permissible to doubtful, iv) Doubtful to Unsuitable, and v) Unsuitable (for irrigation). Out of the two parameters employed for plotting, EC is measured directly or it can be deduced from the value of TDS; whereas, percent sodium is calculated by the equation; Na % = [(Na + K) / (Ca + Mg + Na + K)] * 100 Where, all components on RHS are expressed in meq/L (i.e.,epm). 34 ( Surface water sample Groundwater sample) Fig. 3.1: Irrigational suitability of waters of the study area (after Wilcox, 1978) Table 3.1: Classification of groundwaters of the study area for irrigation (after Wilcox, 1948) Water samples Surface water samples (n = 3) Groundwater samples (n = 37) Suitability for irrigation* Excellent to Good Good to Permissible Permissible to Doubtful Doubtful to Unsuitable Unsuitable 66.66 ___ 33.33 ___ ___ ___ ___ (%) (%) 72.98 27.02 (%) (%) ___ The surface water sample except one comes under excellent to good. Majority of the groundwater sample is excellent to good. From entire samples, only one sample comes under permissible to doubtful. 35 3.2.2 USSL classification The United States Salinity Laboratory (USSL) devised a graphical methodology for assessing the suitability of groundwaters for irrigation purpose. It makes use of SAR (on the Y-axis) and EC (on the X-axis). The plots of groundwaters are divided into distinct classes both on the X- and Yaxes. On the X-axis, salinity (hazard) is divided into low salinity (C1), medium salinity (C2), moderately high salinity (C3), high salinity (C4), and very high salinity (C5). Similarly, on the Y-axis, sodium (alkali hazard) is divided into low sodium (S1), moderate sodium (S2), high sodium (S3), and very high sodium (S4). Suitability of water samples from the study area is plotted in Fig. 3.2. ( Surface water sample Groundwater sample) Fig. 3.2 USSL Diagram for irrigation suitability Every sample comes under C1-S1 area. So, Sodium hazard and salinity hazard is low for all samples and showing very good specific conductance. 36 3.2.3 Classification based on Sodium Percentage (Na%) Eaton (1950) classified waters based on Na%. As per his classification, water carrying more than 60% sodium is unsafe for irrigation. Sodium percentage values for the water samples are presented in Table 3.2. ( ) Where, all components on RHS are expressed in meq/L (i.e.,epm). Table 3.2: Classification of groundwaters of the study area for irrigation on the basis of Sodium Percentage (after Eaton, 1950) % of Na values <20% Water Class Excellent 20-40% Good 40-60% Permissible 60-80% Doubtful >80% Unsuitable Sample numbers Count & % of Samples 5,25,38 3,14,16,17,19,20,23 24,30,33,37 2,6,7,11,13,15,22, 26,27,28,34,35,36 40 4,8,9,10,12,18,21, 29,31,32,39 1 3-7.5% 11-27.5% 14-35% 11-27.5% 1-2.5% Majority of the samples comes under ‘Permissible’ water class. ‘Good’ and ‘doubtful’ water classes having equal number of samples. Only one sample is unsuitable Table 3.3: Summary of the classification of groundwaters of the study area for irrigation on the basis of Sodium Percentage (after Eaton, 1950) Sample numbers Count & % of Samples % Na Water Class >60% Unsafe for Irrigation 1,4,8,9,10,12,18,21 29,31,32,39 12 & 30% <60% Suitable for Irrigation 2,3,5,6,7,11,13,14,15,16,17,19, 20,22,23,24,25,26,27,28,30,33, 34,35,36,37,38,40 28 & 70% Most of the samples are suitable for irrigation. Only 30% of the samples are unsafe for irrigation. 37 3.2.4 Classification based on Residual Sodium Carbonate (RSC) Eaton (1950) also suggested the use of RSC for evaluation of waters for agricultural purposes. Groundwaters with RSC value > 2.5 meq/L are unsuitable for irrigation. RSC values for the water samples are presented in Table 3.2. Where, all components on RHS are expressed in meq/L (i.e.,epm). Table 3.4: Classification of groundwaters of the study area for irrigation on the basis of Residual Sodium Carbonate (RSC), (after Eaton, 1950) Water Class Sample numbers Count & % of Class <1.25 Good 1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,1 9,20,21,22,23,24,25,26,27,28,29,30,31,32,33, 34,36,37,38,39,40 39 &97.5% 1.252.5 Medium 35 1 &2.5% >2.5 Bad(unsuitable for irrigation) Nil Nil RSC Majority of samples are good for irrigation. Except one sample all other samples are comes under ‘good’ water class. 3.2.5 Classification based on Sodium Adsorption Ratio (SAR) The SAR value of the irrigation water quantifies the relative proportions of sodium to calcium and magnesium (Ayers and Westcot, 1985). Along with salinity, SAR is a factor that influences the rate of infiltration of water (Simsek and Gunduz, 2007). Richards (1954) has classified waters (for irrigation purpose) based on the value of SAR as; Excellent (SAR < 10), Good (SAR 10-18), Fair (SAR 18-26), and Poor (SAR > 26). ( √ ) Where, all components on RHS are expressed in meq/L (i.e.,epm). 38 Table 3.5: Classification of groundwaters of the study area for irrigation on the basis of Sodium Absorption Rate (SAR), (after Richards, 1954) SAR (Richards,1954) 26 Water Class Sample numbers Excellent Good Fair Poor All 40 samples Nil Nil Nil Count & % of Samples 40 & 100% Nil Nil Nil Table 3.6: Some computed parameters for the water samples of the study area Sample SAR RSC PI USSL classification No. (Doneen) Salinity Sodium hazard- - - -3.987 -1.100 -24.24 -0.938 -1.283 -0.501 -1.115 -0.815 -0.196 -0.614 -0.699 -0.975 -1.582 -5.327 -5.641 -0.672 -3.055 -0.957 -1.910 -0.507 -7.881 -0.938 -40.748 -1.732 -1.221 -4.140 -1.178 -4.932 -0.204 -0.286 -1.591 - C-1 C-1 C-1 C-1 C-1 C-1 C-1 C-1 C-1 C-1 C-1 C-1 C-1 C-1 C-1 C-1 C-1 C-1 C-1 C-1 C-1 C-1 C-1 C-1 C-1 C-1 C-1 C-1 C-1 C-1 C-1 C-1 C-1 S-1 S-1 S-1 S-1 S-1 S-1 S-1 S-1 S-1 S-1 S-1 S-1 S-1 S-1 S-1 S-1 S-1 S-1 S-1 S-1 S-1 S-1 S-1 S-1 S-1 S-1 S-1 S-1 S-1 S-1 S-1 S-1 S-1 MgHazard NCH SSP KI Na% - -4344.02 -9179.91 -2075.92 - -1269.95 - - - -14060 - -1492.08 - -2082.54 -8824.65 -13203.5 -8297.45 -7124.50 -7424.05 -1867.54 -3983.10 - 432.50 - - -9097.00 -7962.25 -6423.90 -1076.90 -6523.00 -3332.54 -2898.65 - 39 Sample SAR RSC PI USSL classification No. (Doneen) Salinity Sodium hazard- - - - -69.720 -0.850 -0.928 - C-1 C-1 C-1 C-1 C-1 C-1 C-1 S-1 S-1 S-1 S-1 S-1 S-1 S-1 MgHazard NCH SSP KI Na% - - - - - - -2005.15 - - -2260.55 -2198.20 ● The average value of sodium absorption ratio (SAR) is 3.2. Maximum and minimum value of SAR is 8.168 and 0.086 respectively. The average value of sodium absorption ratio (SAR) of surface water is 4.798. Maximum and minimum value of SAR for surface water is 8.168 and 1.603 respectively. The average value of sodium absorption ratio (SAR) of groundwater is 3.075. Maximum and minimum value of SAR for groundwater is 7.42 and 0.086 respectively. The average value of SAR for surface water is higher than the average value of SAR for groundwater. ● The average value of Residual sodium carbonate (RSC) is -4.78. Maximum and minimum value of RSC is 2.169 and -69.72 respectively. The average value of Residual sodium carbonate (RSC) of surface water is -13.8. Maximum and minimum value of RSC for surface water is 0.047 and -14.748 respectively. The average value of Residual sodium carbonate (RSC) of groundwater is -4.05. Maximum and minimum value of RSC for groundwater is 2.17 and -69.72 respectively. The average value of RSC for surface water is lesser than the average value of RSC for groundwater. ● The average value of permeability index (PI) is 66.30. Maximum and minimum value of PI is 94.79 and 3.356 respectively. The average value of permeability index (PI) of surface water is 63.147. Maximum and minimum value of PI for surface water is 94.797 and 19.012 respectively. The average value of permeability index (PI) of groundwater is 66.531. Maximum and minimum value of PI for groundwater is 93.48 and 3.356 respectively. The average value of PI for surface water is lesser than the average value of PI for groundwater. ● In USSL classification every samples having low salinity (C-1) and low sodium hazard (S-1). 40 ● The average value of Mg – hazard is 47.26 and maximum and minimum value of Mg – hazard is 88.92 and 9.1 respectively. The average value of Mg – hazard of surface water is 45.185. Maximum and minimum value of Mg – hazard for surface water is 50.088 and 35.427 respectively. The average value of Mg – hazard of groundwater is 47.423. Maximum and minimum value of Mg – hazard for groundwater is 88.92 and 9.105 respectively. The average value of Mg – hazard for surface water is lesser than the average value of Mg – hazard for groundwater. ● The average value of Non – carbonate hardness (NCH) is -3595.22. Maximum and minimum value of NCH is- and -17574 respectively. The average value of Non – carbonate hardness (NCH) of surface water is 1326.31. Maximum and minimum value of Non – carbonate hardness (NCH) for surface water is 17147.6 and -8824.65 respectively. The average value of Non – carbonate hardness (NCH) of groundwater is -3997.51. Maximum and minimum value of Non – carbonate hardness NCH for groundwater is 47457.7 and -17574.7 respectively. The average value of NCH for surface water is greater than the average value of NCH for groundwater. ● The average of soluble sodium percentage (SSP) is 48.34. Maximum and minimum of SSP is 80.65 and 0.7 respectively. The average value of soluble sodium percentage (SSP) of surface water is 51.475. Maximum and minimum value of soluble sodium percentage (SSP) for surface water is 80.65 and 14.097 respectively. The average value of SSP of groundwater is 48.085. Maximum and minimum value of SSP for groundwater is 79.1 and 0.705 respectively. The average value of SSP for surface water is greater than the average value of SSP for groundwater. ● The average of Sodium Percentage (Na%) is 48.45. Maximum and minimum of Na% is 80.71 and 0.71 respectively. The average value of Na% of surface water is 51.57. Maximum and minimum value of Na% for surface water is 80.708 and 14.27 respectively. The average value of Na% of groundwater is 48.207. Maximum and minimum value of Na% for groundwater is 79.1 and 0.707 respectively. The average value of Na% for surface water is greater than the average value of Na% for groundwater. ● The average of Kelly’s Index (KI) is 1.331. Maximum and minimum of Kelly’s Index (KI) is 4.17 and 0.01 respectively. The average value of Kelly’s Index (KI) of surface water is 1.937. Maximum and minimum value of Kelly’s Index (KI) for surface water is 4.168 and 0.164 respectively. The average value of Kelly’s Index (KI) of groundwater is 41 1.282. Maximum and minimum value of Kelly’s Index (KI) for groundwater is 3.78 and 0.007 respectively. The average value of KI for surface water is greater than the average value of KI for groundwater. 3.2.6 Classification based on Permeability Index (PI) Doneen (1962) proposed the permeability index based on the relation of bicarbonate and Ca-MgNa ions. The classification based on PI is as follows; (i) Class I (Safe) – PI < 25, (ii) Class II (Allowable) – PI 25-75, and (iii) Class III (Unsafe) – PI > 75. In the present study area, more groundwaters (72%) fall in class III compared to those from irrigated areas (> 67%) (Table 3.2). √ ( ) Where, all components on RHS are expressed in meq/L (i.e.,epm). Table 3.7: Classification of groundwaters of the study area for irrigation on the basis of Permeability Index(PI), (after Doneen, 1962) PI Water Class Class III 0-25% (maximum permeability) 25-75% 75100% Class II Sample numbers 5,25,38 3 & 7.5% 3,7,11,14,16,17,19,20,21, 23, (little permeability) 24,26,27,28,30,33,34,37,39 Class I 1,2,4,6,8,9,10,12,13,15,18, (permeable) Count & % of Samples 22,29,31,32,35,36,40 19 & 47.5% 18 & 45% Majority of the sample comes under Class I and Class II. Only three samples come under Class III. Class II and Class III are more suitable for irrigation. Table 3.8: Summary of the classification of groundwaters of the study area for irrigation on the basis of Permeability Index (PI), (after Doneen, 1962) PI Water Class < 25% Class I(safe) 25-75% Class II(Allowable) >75% Class III(unsafe) Sample numbers 5,25,38 3,7,11,14,16,17,19,20,21, 23, 24,26,27,28,30,33,34,37,39 1,2,4,6,8,9,10,12,13,15,18, 22,29,31,32,35,36,40 Number & % of Samples 3 &7.5% 19 & 47.5% 18 &45% 42 Majority of the sample comes under Class II and Class III. Only three samples come under Class I. Class I and Class II are more suitable for irrigation. 22 samples are allowable and 18 samples are unsafe for irrigation. 3.2.7 Classification based on Magnesium Hazard Magnesium-ion concentration plays an important role in the productivity of soil (Haritash et al, 2008). According to Paliwal (1972), magnesium hazard less than 50 indicates that the water is suitable for irrigation. ( ) Where, all components on RHS are expressed in meq/L (i.e.,epm). Table 3.9: Classification of groundwaters of the study area for irrigation on the basis of Magnesium Hazard (MH), (after Paliwal, 1972) MH Water Classification < 50 Suitable for Irrigation Sample Numbers 1,3,5,8,9,10 Count & % of Samples 6 & 15% >= 50 Unsuitable for 2,4,6,7,11,12,13,14,15,16,17,18,19,20,21,22,23,24, Irrigation 25,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40 34 & 85% Most of the sample have Magnesium Hazard >=50 which means unsuitable for irrigation. Only 6 samples are suitable for irrigation. 3.2.8 Classification based on Kelly’s Index (KI) Kelly (1940) determined the hazardous effect of sodium on water quality for irrigation usage in terms of Kelly’s Index (KI), also called Kelly’s Ratio. It is computed as shown below; ( ) Where, all components on RHS are expressed in meq/L (i.e.,epm). Kelly’s ratio of more than one indicates excessive sodium in water. Therefore, water with Kelly’s ratio less than one are suitable for irrigation, while those with a ratio of more than one are unsuitable. 43 Table 3.10: Classification of groundwaters of the study area for irrigation on the basis of Kelly’s Index(KI), (after Kelly, 1940) KI Water Class <1 Good for Irrigation >1 Not Good for Irrigation Count & % of Class Sample numbers 2,3,5,11,14,16,17,19,20,23,24,25 ,26, 21 & 52.5% 27,28,30,33,34,35,37,38 1,4,6,7,8,9,10,12,13,15,18,21, 19 & 47.5% 22 ,29,31,32,36,39,40 Majority of samples are having <1 Kelly’s Index, that means suitable for irrigation. 21 samples are good for irrigation and 19 samples are not good for suitable for irrigation. 3.2.9 Classification based on Non-Carbonate Hardness (NCH) The hardness of water relates to the reaction with soap since Ca and Mg ions precipitate soap. Hardness is expressed as ppm of CaCO3. If the hardness as CaCO3 exceeds the difference between the alkalinity as CaCO3 and hardness as CaCO3, it is termed as non-carbonate hardness. It is also called permanent hardness (Nagaraju et al, 2014). Noncarbonate hardness is contributed by salts such as calcium chloride (CaCl2), magnesium sulfate (MgSO4), and magnesium chloride (MgCl2) (Wilson, 2010). NCH is calculated using the following formula; Where, all components on RHS are expressed in meq/L (i.e.,epm). Table 3.11: Classification of groundwaters of the study area for irrigation on the basis of Non-Carbonate Hardness (NCH) (after Raghunath, 1987) NCH (Raghunath,1987) Water Class Sample numbers Count & % of Samples 1,2,3,4,6,7,8,10,11,12,13,14,15, <0 Safe 16, 17,18,19,20,22,24,26,27,28, 34 &85% 29,31, 32,33,34,35,36,37,39,40 >0 Unsafe 5,9,21,23,25,38 6 &15% Majority of the samples come under safe class. Only 6 samples come under unsafe class. 34 samples are suitable for irrigation and 6 samples are not suitable for irrigation. 44 3.2.10 Classification based on Soluble Sodium Percentage (SSP) SSP is an important criterion to assess the water quality for agriculture. It reflects the potential of deterioration of the soil physical properties and can affect plant growth. The formula for calculation of SSP and the criteria for classification are given below. ( ) Where, all components on RHS are expressed in meq/L (i.e.,epm). Water belonging to the excellent, good, and permissible categories may be used for irrigation purposes. Doubtful waters were considered to be harmful and unsuitable for crop cultivation (Wilcox, 1955). Table 3.12: Classification of groundwaters of the study area for irrigation on the basis of Soluble Sodium Percentage (SSP) (after Wilcox, 1955) SSP Water Class Sample Numbers Count & % of Samples <50 Good 2,3,5,11,14,16,17,19, 20,23,,24,25,26,27, 21 & 52.5% 28,30,33,34,35,37,38 >50 Unsuitable 1,4,6,7,8,9,10,12,13,15,18,21,22,29,31,32, 19 & 47.5% 36,39,40 Soluble sodium percentage (SSP) of majority samples comes under Good Class. 21 Samples are good for irrigation and 19 are unsuitable for irrigation. 3.3 Suitability for industrial use For ascertaining the suitability of water of study area for industrial purposes, three parameters have been considered in this study. They are (1) Corrosivity Ratio (CR), (2) Langelier Saturation Index (LSI), and (3) Ryznar Stability Index. Water samples of the study area are subjected to these three parameters to know their industrial-suitability. In this study, water for industrial use refers to applications such as cooling water, boiler feed water and manufacturing processes. The two most important factors deciding the suitability of water for industrial purposes are the precipitation of carbonates and corrosivity. 45 3.3.1 Langelier Saturation Index (LSI) Formation of scale is one of the primary problems associated with water-use in heavy industries. For monitoring the scale formation, Langelier (1936) introduced a Saturation Index, called the Langelier Saturation Index (LSI) to evaluate the scale-forming property of water. Actually, LSI predicts the stability of CaCO3 in water. That is, whether a water sample will precipitate, dissolve or be in equilibrium with CaCO3 (Haritash et al, 2016). In other words, the LSI is an approximate indicator of the degree of saturation of calcium carbonate in water. The LSI is calculated as the difference between the actual pH of the water and the pH saturated with CaCO3 (pHs). That is, LSI = pH (measured) - pHs Thus, LSI is expressed as the difference between the actual system pH and the saturation pH, where the latter is defined as the pH at which the water will get saturated with CaCO3. pHs = (9.3+A+B) – (C+D), where, A = (Log10 [TDS] - 1) / 10 B = -13.12 x Log10 (oC + 273) + 34.55 C = Log10 [Ca2+ as CaCO3] - 0.4, and D = Log10 [alkalinity as CaCO3] Further, the interpretation is based on the following; If LSI is negative: No potential to scale, the water will dissolve CaCO3 If LSI is positive: Scale can form and CaCO3 precipitation may occur If LSI is close to zero: Borderline scale potential. 3.3.2 Ryznar Stability Index (RSI) Along with LSI, RSI is designed to be a predictive tool for calcium carbonate scale formation. The Ryznar index is an empirical method for predicting scaling tendencies of water based on study of operating results with water at various saturation indices. The Stability Index developed by John Ryznar in 1944 used the Langelier Index (LSI) as a component in a new formula to improve the accuracy in predicting the scaling or corrosion tendencies of water. Formula for calculating RSI and the interpretation criteria are given below. RSI = (2 x pHs) – pH (measured) 46 ▪ RSI << 6 the scale tendency increases as the index decreases ▪ RSI >> 7 the calcium carbonate formation probably does not lead to a protective corrosion inhibitor film ▪ RSI >> 8 mild steel corrosion becomes an increasing problem. Table 3.13: Suitability classification of groundwaters of the study area for industrial use on the basis of Ryznar Stability Index (RSI) (after Ryznar, 1944). RSI Range <5.5 RSI(InferenceSample numbers Ryznar, 1944) Heavy scale will form 7,13,20,25,33,34, 35,37 5.5 – 6.2 Scale will form 2,5,11,14,15,16,17,26,27, 28,30,38 6.2 – 6.8 No difficulties 1,19 6.8 – 8.5 Water is aggressive >8.5 Water is very aggressive Count & % of Samples 8 & 20% 12 & 30% 2 & 5% 3,10,12,18,22,23,29,31, 36,39,40 12 & 30% 4,6,8,9,21,24 6 & 15% Majority of the samples are come under 5.5-6.2 and 6.8-8.5 range. 22 samples are suitable for irrigation and 18 are unsuitable for irrigation. Table 3.14: Suitability classification of groundwaters of the study area for industrial use on the basis of the Ryznar Stability Index (RSI) (after Carrier, 1965). RSI Range RSI (InferenceCarrier 1965) 4-5 Heavy Scale 7,25 5-6 Light Scale 5,11,13,14,17,20,26,27,28,30,33,34,35,37 14 -35% 6-7 Little scale or Corrosion 1,2,15,17,19,38 6 -15% 7-7.5 Corrosion Significant 3,22,31,32 4 -10% 7.5-9 >9 Sample numbers Heavy Corrosion 4,6,8,10,12,18,23,24, 29,36,39,40 Corrosion 9,21 Number & % of Samples 2 -5% 12 -30% 2 -5% Majority of sample have come under 5-6 RSI range. 16 samples are suitable for irrigation and 24 samples are not suitable for irrigation. 47 3.3.3 Corrosivity Ratio (CR) Corrosivity ratio (CR), calculated using the below-given formula, indicates the possibility of development of corrosivity in metallic pipes and other metallic instruments/parts etc. ( ) ( ( ) ) Where all components on RHS are expressed in terms of mg/L (i.e., ppm). The water is considered safe and non-corrosive if the ratio is less than one and CR>1 is indicative of corrosiveness. Table 3.15: Suitability classification of groundwaters of the study area for industrial use on the basis of Corrosivity Ratio (CR) (after Ryznar, 1944). CR Water Classification <1 Safe & NonCorrosive >1 Corrosive Sample Numbers Count & % of Samples 5,11,14,17,20,22,26,32,35,37,39 11 & 27.50% 1,2,3,4,6,7,8,9,10,12,13,15,16,18,19,21, 29 & 72.5% 23,24,25,27,28,29,30,31,33,34,36,38,40 Most of the samples are having >1 Corrosive ratio. 11 samples are suitable for irrigation and 29 samples are not suitable for irrigation. 48 Table 3.16: Some computed parameters for suitability of Industrial use of the water samples of the study area. Sample No. LSI RSI CR 1 1.010 6.750 1.438 2 1.182 6.007 1.263 3 0.455 7.090 1.025 4 -0.206 8.692 3.163 5 1.334 5.612 0.590 6 -0.103 8.507 1.242 7 2.084 4.583 1.399 8 -0.183 8.666 2.128 9 -1.305 10.849 11.522 10 0.075 8.180 1.964 11 1.360 5.561 0.677 12 0.547 7.645 1.287 13 1.818 5.323 1.493 14 1.251 5.558 0.721 15 1.041 6.088 1.039 16 1.146 5.859 1.873 17 0.850 6.100 0.847 18 -0.103 8.435 4.952 19 1.148 6.304 1.121 20 1.385 5.321 0.383 21 -0.607 9.543 5.046 22 0.609 7.012 0.760 23 -0.115 8.310 2.123 24 -0.414 8.819 2.489 25 2.084 4.582 1.971 26 1.337 5.696 0.943 27 1.406 5.737 4.323 28 1.170 5.961 3.154 29 0.467 7.937 8.024 30 1.255 5.800 1.191 31 0.855 7.069 1.695 32 0.721 7.298 0.575 33 1.313 5.373 1.042 34 1.468 5.485 1.047 35 1.653 5.044 0.563 36 0.337 7.757 1.132 37 1.612 5.057 0.432 38 1.052 6.127 3.633 39 -0.168 8.247 0.991 40 0.112 7.967 1.211 49 ● The average value of Langelier saturation index (LSI) is 0.78 and maximum and Minimum value of LSI is 2.08 and -1.305 respectively. The average value of Langelier saturation index (LSI) of surface water is 1.637. Maximum and minimum value of Langelier saturation index (LSI) for surface water is 2.084 and 1.01 respectively. The average value of Langelier saturation index (LSI) of groundwater is 0.703. Maximum and minimum value of Langelier saturation index (LSI) for groundwater is 2.084 and -1.305 respectively. The average value of LSI for surface water is greater than the average value of LSI for groundwater. ● The average value of Ryznar stability index (RSI) is 6.79 and maximum and minimum value of RSI is 10.849 and 4.582 respectively. The average value of Ryznar stability index (RSI) of surface water is 5.551. Maximum and minimum value of Ryznar stability index (RSI) for surface water is 6.75 and 4.582 respectively. The average value of Ryznar stability index (RSI) of groundwater is 6.899. Maximum and minimum value of Ryznar stability index (RSI) for groundwater is 10.849 and 4.589 respectively. The average value of RSI for surface water is lesser than the average value of RSI for groundwater. ● The average value of Corrosivity ratio (CR) is 2.06 and maximum and minimum value of CR is 11.52 and 0.38 respectively. The average value of Corrosivity ratio (CR) of surface water is 1.634. Maximum and minimum value of Corrosivity ratio (CR) for surface water is 1.971 and 1.438 respectively. The average value of Corrosivity ratio (CR) of groundwater is 2.097. Maximum and minimum value of Corrosivity ratio (CR) for groundwater is 11.522 and 0.383 respectively. The average value of CR for surface water is lesser than the average value of CR for groundwater. 50 3.4 Suitability for drinking 3.4.1 Suitability based on TDS For the evaluation of water for human consumption, the following groups can be allotted: fresh water, brackish water, salt water and extremely salt water (Chebotarev, 1955). Table 3.17: Suitability for human consumption of waters based on TDS (After Chebotarev, 1955) Qualitative groups Major Subdivisions Approximat e salinity Sample numbers Frequency % 28 70% 12 30% (mg/L) Groups 1,2,4,5,6,7,8,9,10,11 Good potable < 500 12,13,19,21,22,23,24,25 ,26,27,29,31,32,36,37, 38,39,40 Fresh water Brackis h water Salt water Fresh < 700 3,14,15,16,17,18,20, 28,30,33,34,35 Fairly fresh 700 – 1500 Nil - - Passably fresh 1500 – 2500 Nil - - Slightly brackish 2500 – 3200 Nil - - Brackish 3200 – 4000 Nil - - Definitely brackish (the limit for human consumption ) 4000 – 5000* Nil - - Slightly salt 5000 – 6500 Nil - - Salt 6500 – 7000 Nil - - Very salt 7000 – 10000 Nil - - Extremely salt More than 10000 Nil - - * The use for human consumption of subterranean water of higher salinity (up to 8000 mg/L) without noticeable harm to health has been recorded (Ward, 1946). 51 Majority of the samples are come under ‘good portable’ subdivision in fresh water. All samples come under fresh water. All 40 samples are suitable for human consumption. Table 3.18: Standards for Drinking Water (BIS, 2015) S.No. Parameters BIS Standards Sample No & % 1 pH 6.5 – 8.5 [2,3,4,5,6,8,9,10,11,14,15,17, 18,20,21,22,23,24,26,28,30, 33,34,35,36,37,38,39,40] &[72.5%] 2 TDS (mg/L) 500 [1,2,4,5,6,7,8,9,10,11,12,16,17 18,19,20,21,22,23,24,25,26, 29,31,32,36,38,40] & [70%] 3 Calcium (mg/L) 75 [1,2,4,6,8,9,10,11,12,13,14,15 ,18,19,20,21,22,23,24,26,27,29 ,31,32,34,35,36,37,39,40] &[75%] 4 Magnesium (mg/L) 30 [1,2,3,4,6,8,9,10,12,13,18,21, 22,24,29,31,32,35,36,39,40] & [52.5 %] 5 Sodium (mg/L) - - 6 Potassium (mg/L) - - 7 Chlorine (mg/L) 250 [1,2,3,4,5,6,8,9,10,11,12,13,14,15, 16,18,19,20,21,22,23,24,26,29,30, 31,32,33,34,35,36,37,39,40] &[85%] 8 Total Hardness(as CaCO3) (mg/L) 200 [1,8,9,10,21,24,31,32,39, 2,4,6,7,12,19,23,29,37,40] &[47.5%] 9 Total Alkalinity(as CaCO3) (mg/L) 200 [1,3,4,6,8,9,10,12,18,19,21,22 ,23,24,29,31,32,36,39,40] & [50%] 10 Sulphate (mg/L) 200 [1,2,3,4,5,6,7,8,9,10,11,12,13,14,15 ,16,17,18,19,20,21,22,23,24,25,26, 30,31,32,33,34,35,36,37,38,39,40] & [92.5%] According to BIS standards, 72.5% of samples come under the pH limit to be suitable for drinking purposes. 70% of the samples tested are suitable for drinking water based on the TDS amount present in them. 75 % of the samples tested are suitable for drinking water based on the BIS regulations of calcium that should be present in drinking water. 52.5 % of sample has the 52 permissible amount of magnesium so these samples are suitable for drinking water. 85% of samples come under BIS chlorine limit to be suitable for drinking water purpose. 47.5% of samples tested come under BIS limit of Total Hardness (as CaCO3) to be suitable for drinking water. 50 % of the samples tested are suitable for drinking water based on the BIS regulations of Total Alkalinity (as CaCO3) that should be present in drinking water. 92.5% of the samples tested are suitable for drinking water based on the sulphate amount present in them. Table 3.19: Standards for Drinking Water (WHO, 2017) S.No. Parameters WHO Standards 1 pH 6.5 - 8.5 2 TDS (mg/L) 500 3 Calcium (mg/L) 75 4 Magnesium (mg/L) 50 5 Sodium (mg/L) 200 6 Potassium (mg/L) 20 7 Chlorine (mg/L) 250 8 Total Hardness(as CaCO3) (mg/L) Total Alkalinity(as CaCO3) (mg/L) - 9 10 Sulphate (mg/L) 200 500 Sample No & % [2,3,4,5,6,8,9,10,11,14,15,17, 18,20,21,22,23,24,26,28,30, 33,34,35,36,37,38,39,40] &[72.5%] [1,2,4,5,6,7,8,9,10,11,12,16,17 18,19,20,21,22,23,24,25,26, 29,31,32,36,38,40] & [70%] [1,2,4,6,8,9,10,11,12,13,14,15 ,18,19,20,21,22,23,24,26,27,29 ,31,32,34,35,36,37,39,40] & [75%] [2,3,4,5,6,7,8,9,10,11,12,13,14,15 ,18,19,20,21,22,24,26,27,29,31, 32,34,35,36,37,39,40] & [80%] [1,2,3,4,5,6,7,8,9,10,11,12,13,14,15 ,16,17,18,19,20,21,22,23,24,25,26 ,27,28,29,30,31,32,33,34,35,36,37 ,38,39,40] & [100%] [1,2,3,4,5,6,7,8,9,10,11,12,13,14,15 ,16,17,18,19,20,21,22,23,24,25,26 ,27,28,29,30,31,32,33,34,35,36,37 ,38,39,40] & [100%] [1,2,3,4,5,6,8,9,10,11,12,13,14,15, 16,18,19,20,21,22,23,24,26,29,30, 31,32,33,34,35,36,37,39,40] &[85%] [1,3,4,6,8,9,10,12,18,19,21,22 ,23,24,29,31,32,36,39,40] & [50%] [1,2,3,4,5,6,7,8,9,10,11,12,13,14,15 ,16,17,18,19,20,21,22,23,24,25,26 ,27,28,29,30,31,32,33,34,35,36,37 ,38,39,40] & [100%] 53 According to BIS standards, 72.5% of samples come under the pH limit to be suitable for drinking purposes. 70% of the samples tested are suitable for drinking water based on the TDS amount present in them. 75 % of the samples tested are suitable for drinking water based on the BIS regulations of calcium that should be present in drinking water. 80 % of the sample has a permissible amount of magnesium so these samples are suitable for drinking water. All of the samples tested are suitable for drinking water based on the BIS regulations of sodium and potassium that should be present in drinking water. 85% of samples come under BIS chlorine limit to be suitable for drinking water purpose. 50 % of the samples tested are suitable for drinking water based on the BIS regulations of Total Alkalinity (as CaCO3) that should be present in drinking water. 100% of the samples tested are suitable for drinking water based on the sulphate amount present in them. 54