Water is vital for life on Earth and plays a key role in sustaining ecosystems. It covers about 71% of the Earth's surface.^[1] The health of aquatic life depends on water quality, which is influenced by various environmental factors. Studying physico-chemical properties of water is crucial, as these factors directly impact biological productivity.^[2] Any changes in water quality that harm organisms or make it unfit for use are categorized as pollution. Freshwater is essential for human health, agriculture, ecosystems, and industry. Urbanization, population growth, and industrialization have increased demand for quality water.^[3] These factors also contribute to water pollution, especially groundwater contamination in rural areas where rivers, canals, or dams are unavailable. Groundwater, once considered safe for drinking, is now at risk due to industrial waste and human activities. The quality of groundwater depends on soil type, recharge water, and human impact.^[4]

Groundwater, a vital resource for domestic and agricultural needs. About 80% of rural and 50% of urban drinking water needs in India rely on groundwater.^[5] However, pollution from toxic elements, industrial discharge, and harmful microorganisms poses serious health risks, including gastrointestinal diseases. Rapid urbanization and poor waste management have worsened groundwater quality.^[6] Contaminants seep through soil, leading to long-term water quality issues. Treating polluted groundwater is costly and often ineffective. Water scarcity and pollution in summer months further strain resources, especially in rural areas.^[7] India spends significant resources on treating contaminated water to make it potable.^[8] Safe drinking water remains a challenge due to unplanned urban growth, inadequate infrastructure, and a lack of awareness. Efforts to monitor and improve water quality are critical for addressing water-borne diseases and ensuring public health.^[9]

Globally, freshwater scarcity is a growing concern. Niti-Aayog has reported that 30 Indian cities are expected to face acute water shortages in the coming decades, with 40% of the population potentially experiencing drinking water scarcity by 2030.^[10] Freshwater resources are increasingly polluted by untreated sewage, industrial effluents, and agricultural runoff. This imbalance between water demand and supply is a major challenge for sustainable development. Protecting water resources requires strict pollution control, public awareness, and robust policies.^[11] Developing and developed countries alike must prioritize water quality management. Clean water is essential for survival, economic growth, and environmental health.^[12] Sustainable practices and global cooperation are key to addressing the water crisis and ensuring access to safe drinking water for all.^[13]

Preserving water quality offers numerous benefits. Just like any essential substance, water is beneficial to the body when within safe and acceptable limits, but exceeding these limits or contamination can lead to harmful effects, disrupting health and overall well-being.^[14] Reducing water pollution not only lowers the prevalence of water-borne diseases but also minimizes costs associated with water supply for domestic, industrial, and agricultural purposes.^[15] It helps prevent land degradation and supports the growth of fisheries. Additionally, it provides non-economic advantages such as enhanced environmental quality, healthier aquatic ecosystems, and increased biodiversity.^[16]

This study aims to analyze water quality through parameters like Total Solids (TS), Total Dissolved Solids (TDS), Hardness, Alkalinity, Chloride, Turbidity, Conductivity, pH, Salinity, Resistivity, Dissolved Oxygen (DO), Nitrite, Nitrate, Arsenic, and Lead. Recent evaluations of water quality in Allahabad reveal that urbanization and declining groundwater levels have led to increased concentrations of total solids and dissolved solids. This trend suggests a potential rise in other pollutants, including impurities and heavy metals. Improper water resource management has likely contributed to higher levels of hardness, alkalinity, turbidity, and chloride.^[17] The growing presence of heavy metals such as arsenic and lead raises significant concerns and underscores the need for monitoring and assessing the water quality in Allahabad. Furthermore, available data indicate a rise in cancer cases in the region, prompting a focused investigation into arsenic and lead contamination to better understand its potential impact on public health

The project titled "Water Quality Analysis: Physico-Chemical Analysis of Drinking Water from Different Regions of Allahabad" was initiated in February 2015 at the Centre of Food Technology, University of Allahabad. The allotted period for the project was three months.

Sample Collection

Water Samples

Water samples were collected from seven areas in Allahabad district that are most prone to waterborne diseases and epidemics. These areas were Mumfordganj, Daraganj, Jhunsi, Beli, Phaphamau, CFT, and Civil Lines. Clean and sterilized PET bottles with caps were used for the collection of water samples.

Figure 1: Sample collection in sterile bottle from tap water

Sample Collection Procedure

The tap was opened for five minutes to allow any impurities to drain out. After this, the sterilized bottle was filled with water up to the neck level. The bottle was then capped and labeled appropriately for identification.

Environmental Conditions

The sample collection took place in February 2015, during the specified season for the study.

Storages: - Samples were stored at room temperature in the instrumental lab (CFT, Allahabad) The samples were analyzed for various parameters and their test methods are as follows:

Table 1: Various Parameters and their analyzing methods

1. pH Measurement [IS: 3025 (P11)-1983 (Re 2002)]

Principle
The pH of a solution is determined by measuring the electromotive force (EMF) of a system. This system includes an indicator electrode (e.g., a glass electrode sensitive to hydrogen ions) and a reference electrode (e.g., a calomel electrode). The two electrodes are connected through a liquid junction, and the EMF is measured using a pH meter, which acts as a high-impedance voltmeter calibrated in pH units.

Procedure:

A pH meter (Metrohm model) was calibrated using buffer solutions traceable to NIST standards (Merck) with pH values of 4.01, 7.00, and 9.00 at 25°C. The electrode was rinsed with Milli-Q distilled water. The pH of the water sample was measured at the same temperature.

2. Conductivity Measurement [IS: 3025 (P14)-1984 (Re 2006)]

Principle:
The specific conductance of a solution is measured using a wheatstone bridge circuit. A variable resistor is adjusted to match the resistance of the solution placed between the electrodes of a conductivity cell. The electrodes are platinized to ensure accurate measurements.

Procedure:

Conductivity was directly measured in µS/cm using a conductivity meter. The instrument was calibrated with a potassium chloride standard solution (CRM) traceable to NIST (Merck), with a conductivity of 1.41 µS/cm. The electrode was rinsed with Milli-Q distilled water, and the conductivity of the sample was measured.

3. Salinity

Principle:
Salinity is determined by measuring the resistance of the solution using a wheatstone bridge. A variable resistor is adjusted to match the resistance of the unknown solution placed between platinized electrodes in a standard salinity cell.

Procedure:

Salinity was measured directly in mg/L. The electrode was rinsed with milli-Q distilled water before measuring the salinity of the water sample.

4. Resistivity

Principle:
Resistivity is measured using a wheatstone bridge, where a variable resistor is adjusted to match the resistance of the unknown solution. The solution is placed between platinized electrodes in a standard resistivity cell.

Procedure:

Resistivity was measured directly in kΩ. The electrode was rinsed with Milli-Q distilled water before measuring the resistivity of the sample.

5. Turbidity [IS: 3025 (P10) - 1984 (Revised 2006)]

Principle:
Turbidity is determined by measuring the scattering of light caused by suspended particles in water, a method known as Nephelometry. A turbidity meter is suitable for samples with moderate turbidity, while a nephelometer is used for low-turbidity samples. The intensity of scattered light is proportional to turbidity levels.

Procedure:

The turbidity meter (Aqua Lytic model) was calibrated using four standard concentrations: 1, 10, 100, and 1000 NTU at 25°C. The water sample was placed in a sample tube and inserted into the turbidity meter to record the turbidity reading.

6. Hardness [IS: 3025 (P 21)-Revised 2009]

Principle:
The determination of hardness relies on the ability of ethylenediaminetetraacetic acid (EDTA) or its disodium salt to form stable complexes with calcium (Ca²⁺) and magnesium (Mg²⁺) ions. When Eriochrome Black T (EBT) is added to a solution containing these ions at a pH of 10, it forms a wine-red complex. During titration with standard EDTA solution, calcium and magnesium ions bind with EDTA, breaking the dye-metal complex, and the solution changes from wine-red to blue, indicating the endpoint of the titration.

Reaction:
Mg²⁺ + EBT → [Mg-EBT] (Pink Complex)
[Mg-EBT] + EDTA → [Mg-EDTA] + EBT (Blue)

Procedure:                                                                                                                                                                                                A 0.02 N EDTA solution was prepared and standardized using a 0.1% calcium carbonate solution traceable to NIST, with Eriochrome Black T as the indicator. For standardization, 25 ml of 0.02 N EDTA was placed in a 250 ml conical flask, followed by 1 ml of buffer solution and 2 drops of EBT. The solution was titrated with the calcium carbonate solution until the reddish hue disappeared, leaving a sky-blue endpoint. To determine hardness in the water sample, 50 ml of the sample was mixed with 1 ml of buffer (ammonium chloride and ammonium hydroxide), 1 ml of hydroxylamine solution, and 2-3 drops of EBT indicator. The sample was titrated with the standardized EDTA solution until the color changed from brick-red to light blue, and the titer value was recorded.

Calculation

The total hardness, expressed as calcium carbonate (CaCO₃) in mg/L, was calculated using the following formula:

Total Hardness (CaCO₃) = [1000 (V₁ – V₂) / V₃] × CF (CaCO₃), mg/l

Where:

V₁ = volume in ml of the EDTA standard solution used in the titration for the sample,

V₂ = volume in ml of the EDTA solution used in the titration for blank,

V₃ = volume in ml of the sample taken for the test,

CF = X₁/X₂ = correction factor for standardization of EDTA,

X₁ = volume in ml of standard calcium solution taken for standardization, and

X₂ = volume of ml of EDTA solution used in the titration

7. Alkalinity [IS: 3025 (P23)-1983 (Re 2003)]

Principle: Alkalinity of water is the capacity of that water to accept protons. It may be defined as the quantitative capacity of an aqueous medium to react with hydrogen Ions to pH 8.3 (phenolphthalein alkalinity) and then to pH 3.7 (total alkalinity or methyl orange alkalinity). The equation in its simplest form is as follows:

CO₃^–––−+ H⁺ = HCO₃^– — (pH 8·3)

From pH 8.3 to 3.7, the following reaction may occur:

HCO₃^– + H⁺= H₂CO_3\

Procedure

N sodium hydroxide solution was standardized against 0.1 N potassiumhydrogenphthalate solution (NIST Traceable). 0.02 N H₂SO₄ was then standardized against 0.1 N standardized NaOH. 20 ml sample was taken in a 250 ml conical flask then 1-2 drops of phenolphthalein indicator and 1 drop of mixed indicator was added to it, then titrated against 0.02 N H₂SO₄ till light pink end point is reached. Titre value is noted down.

Calculation

Phenolphthalein Alkalinity (as mg/L of CaCO₃):
Phenolphthalein Alkalinity = (A × N × 50,000) / V

Total Alkalinity (as mg/L of CaCO₃):
Total Alkalinity = [(A + B) × N × 50,000] / V   

where: A = ml of standard sulphuric acid used to titrate to pH 8-3,

B = ml of standard sulphuric acid used to titrate from pH 8.3 to pH 3.7

N = normality of acid used, and

V = volume in ml of sample taken for test.

8. Chloride [IS: 3025 (P32)-1988 (Revised 2003)]

Principle
In a neutral or slightly alkaline environment, potassium chromate is used as an indicator during the titration of chlorides with silver nitrate. Chlorides react with silver nitrate to form a precipitate of silver chloride. The endpoint is marked by the formation of a red silver chromate complex.

Procedure
A 0.0141 N silver nitrate solution was standardized using a 0.0141 N sodium chloride solution (traceable to NIST standards). For the test, 100 ml of the water sample was placed in a conical flask, and 1 ml of potassium chromate indicator was added. The sample was titrated with the standardized silver nitrate solution until a pinkish-yellow endpoint was reached. The volume of silver nitrate used was recorded as the titre value.

Calculation:
The chloride concentration, expressed as mg/L, was calculated using the following formula:

Chloride (mg/L) = [(V1 − V2) × N × 35,450] / V3   

where:  V1 = Volume of silver nitrate used for the sample (ml); V2 = Volume of silver nitrate used for the blank titration (ml); V3 = Volume of the sample taken for titration (ml); N = Normality of the silver nitrate solution

9. Total Solids [IS: 3025 (P15)-1984 (Revised 2009)]

Principle
To determine total solids, the water sample is evaporated in a pre-weighed dish on a steam bath. The residue is then dried to a constant weight in an oven at 103–105°C or 179–181°C. The total residue is calculated based on the increase in weight.

Procedure
A clean beaker was preheated at 180°C for 1 hour, cooled in a desiccator, and weighed to determine its constant weight. A 50 ml water sample was placed in the beaker, evaporated at approximately 98°C, and then dried in an oven at 180°C for 1–2 hours until a constant weight was achieved (variation < 0.5 mg). The beaker was cooled in a desiccator before weighing.

Calculation
Total Residue (mg/L) = (1000 × M) / V;  

where:   M = Mass of the total residue (mg); V = Volume of the sample (ml)

10. Total Dissolved Solids [IS: 3025 (P16)-1984 (Revised 2006)]

Principle:
To determine total dissolved solids, the sample is first filtered. The filtrate is then evaporated in a pre-weighed dish on a steam bath, and the residue is dried to a constant weight in an oven at 103–105°C or 179–181°C.

Procedure:
A pre-weighed beaker was heated to 180°C for 1 hour, cooled in a desiccator, and weighed. A 50 ml filtered water sample was placed in the beaker, evaporated at approximately 98°C, and dried in an oven at 180°C for 1–2 hours until a constant weight was achieved (variation < 0.5 mg). The beaker was cooled in a desiccator before final weighing.

Calculation:
Filterable Residue (mg/L) = (1000 × M) / V

Where: M = Mass of the filterable residue (mg); V = Volume of the sample (ml)

11. Lead [IS: 3025 (P47)-1994 (Revised 2003)]

Principle:
Lead content in the sample is analyzed by directly aspirating the sample into the flame of an Atomic Absorption Spectrophotometer (AAS). Standard solutions with varying concentrations are prepared for calibration.

Standard lead solution: 10 mg/L Working standard solutions: 50 mg/L, 70 mg/L, 90 mg/L

Calibration:
A blank solution of 0.1% nitric acid was used, and a calibration graph was plotted using working standard solutions (2.5, 5, and 10 mg/L) against absorbance.

Procedure:
A 250 ml water sample was acidified with 0.1% nitric acid, and 0.5 ml of concentrated HCl was added. The sample was evaporated to a volume of 25 ml, cooled to room temperature, and analyzed using a Perkin Elmer AAS700 to directly measure absorbance and concentration.

Calculation:
Lead (mg/L) = Mean × V′ / V

Where: V′ = Volume of sample after evaporation (ml); V = Initial sample volume (ml)

12. Arsenic [IS: 3025 (P37)-1988]

Principle:
Arsenic content is determined by atomizing the sample into an Atomic Absorption Spectrophotometer (AAS). This method is suitable for concentrations ranging from 0.01 mg/L to 1.0 mg/L, depending on the instrument's sensitivity.

Calibration:
A blank solution of 0.1% nitric acid was used. A calibration graph was plotted using working standard solutions (30, 60, and 90 µg/L) against absorbance.

Procedure:
A 50 ml filtered sample (using Whatman No. 42 filter paper) was added to a 250 ml beaker along with 1 ml of 2.5 N sulfuric acid and 5 ml of 5% potassium persulfate. The mixture was gently boiled on a preheated hot plate until the volume reduced to 10 ml. After digestion, the sample was diluted to 50 ml and analyzed using an AAS to determine the mean arsenic concentration.

Calculation:
Arsenic (µg/L) = Mean × V′ / V

where: V′ = Final volume after digestion (10 ml); V = Initial sample volume (50 ml)

13. Nitrate [IS: 3025 (P34)-1988]

Equipment:

• Ion Chromatography System: Metrohm 883 Basic IC Plus
• Column: Metrosep A Supp 4 (anion exchange)
• Mobile phase: Sodium carbonate (18 mmol/L; 191 mg/L) and sodium bicarbonate (1.7 mmol/L; 143 mg/L)
• Suppressor: 50 mmol
• Rinse solution: Milli-Q water

Procedure:
A substandard solution of 100 mg/L was prepared from the stock solution. Working standard solutions of 10, 5, and 2 mg/L were prepared by serial dilution. Standard solutions were run, and calibration graphs of standard concentrations versus conductivity (µS/cm) were recorded. The sample was filtered through Whatman No. 42 filter paper and a syringe filter (0.45 µm). The filtered sample was injected into the column, and the concentration of nitrate and nitrite was estimated by comparing the sample's graph to the standard calibration graph.

1. pH

The pH levels across different regions of the Allahabad district were found to range from 7.0 to 7.8, which falls within the acceptable range of 6.5 to 8.5, as per the drinking water standards (IS 10500). Maintaining an appropriate pH is crucial to reducing the risk of corrosion or scale formation in water supply systems.^[18] These issues can lead to significant damage and result from complex interactions involving pH, dissolved solids, gases, hardness, alkalinity, and temperature. Furthermore, as pH levels rise, there is a noticeable decline in the effectiveness of chlorine as a disinfectant.

Table 2: The following table shows level of pH in different water samples of tap water

Graph1: The following graph shows level of pH in different water samples of tap water

2. Conductivity

Although conductivity is not directly linked to health concerns for humans or aquatic life, it serves as a valuable indicator of potential water quality issues. Water with elevated mineral content often exhibits higher conductivity, signifying an increased concentration of dissolved solids.^[19] Conductivity reflects the mobility of ions and electrolytes in water and is influenced by the presence of inorganic dissolved solids like chloride, nitrate, sulfate, and phosphate, as well as cations such as sodium, magnesium, calcium, iron, and aluminum.

The standard unit for measuring conductivity is mho or Siemens. Notable changes in conductivity can signal the introduction of pollutants or discharges into the water. Thus, conductivity measurements provide a quick and efficient method to identify potential water quality problems.

Table 3: The following table shows level of conductivity in different water samples of tap water

Graph2: The following graph shows level of conductivity in different water samples of tap water

3. Salinity

Salinity refers to the concentration of salts found on land surfaces, within soil or rocks, or dissolved in water bodies such as rivers and groundwater. While salinity can occur naturally, human activities that disrupt natural ecosystems and alter the hydrology of landscapes often accelerate the movement of salts into rivers and onto land.^[20] This increased salinity has significant environmental and economic consequences, including degradation of natural habitats, reduced agricultural productivity, and damage to both private and public infrastructure.

Table 4: The following table shows level of Salinity in different water samples of tap water

Graph3: The following graph shows level of conductivity in different water samples of tap water

4.Resistivity

Resistivity measures the water's ability to resist ion flow, inversely related to conductivity. Higher resistivity indicates lower dissolved solids and salinity. It is influenced by ions like chlorides, nitrates, sulfates, and various cations. Measured in kilo-ohms (kΩ), changes in resistivity can help detect pollution or other water quality issues efficiently.

Table 5: The following table shows level of Resistivity in different water samples of tap water

Graph4: The following graph shows level of Resistivity in different water samples of tap water

5.Turbidity

Turbidity indicates water cloudiness caused by silt, sand, microbes, or chemical precipitates. Measured in nephelometric turbidity units (NTU) or Jackson units (JTU), it was found that turbidity in Allahabad district ranges from 8.56 to 12.2 NTU, exceeding the acceptable limit of 1 NTU (IS 10500). Treatment is required to make the water suitable for drinking.

Table 6: The following table shows level of Turbidity in different water samples of tap water

Graph5: The following graph shows level of Turbidity in different water samples of tap water

6. Hardness

Hardness in water across Allahabad district ranges from 125 to 265.3 mg/L. High levels at locations like Civil Lines, Daraganj, and Jhunsi are attributed to elevated calcium and magnesium salts, exceeding the permissible limit of 200 mg/L (IS 10500). Areas like Phaphamau, Beli, CFT, and Mumfordganj remain within acceptable levels. Excessive hardness can contribute to heart disease and kidney stones, making such water unsuitable for drinking and household use without treatment.^[21]

Table 7: The following table shows level of Hardness in different water samples of tap water

Graph6: The following graph shows level of Hardness in different water samples of tap water

7. Alkalinity

Alkalinity indicates the presence of natural salts dissolved in water, primarily from the soil. Bicarbonates, hydroxides, and other ions contribute to this property, varying by water source and natural processes.^[22] In Allahabad district, alkalinity ranges from 161.7 to 262.66 mg/L, with some areas exceeding the permissible limit of 200 mg/L (IS 10500). Elevated alkalinity can cause a sour taste and increased salinity, affecting water quality.

Table 8: The following table shows level of Alkalinity in different water samples of tap water

Graph7: The following graph shows level of Alkalinity in different water samples of tap water

8. Chloride

Chloride levels in Allahabad district range from 7.37 to 166.8 mg/L, within the permissible limit of 250 mg/L (IS 10500). Chlorides help identify groundwater contamination from wastewater. Slightly elevated levels may result from natural salt formations or pollution.^[23] Excess chloride (>250 mg/L) gives water a salty taste and may cause laxative effects for those unaccustomed to high concentrations.

Table 9: The following table shows level of Chloride in different water samples of tap water

Graph8: The following graph shows level of Chloride in different water samples of tap water

9. Total Dissolved Solids (TDS)

TDS levels in Allahabad district range from 268 to 764.7 mg/L. Some areas, such as Daraganj (764.7 mg/L), Civil Lines (530 mg/L), Jhunsi (522 mg/L), and CFT (517 mg/L), exceed the permissible limit of 500 mg/L (IS 10500). TDS mainly consists of dissolved inorganic substances, and high levels can lead to hardness, unpleasant taste, mineral deposits, and corrosion.

Table 10: The following table shows level of TDS in different water samples of tap water

Graph9: The following graph shows level of TDS in different water samples of tap water

10. Total Solids (TS)

TS levels in Allahabad district range from 308.67 to 854 mg/L. Areas such as Daraganj (854 mg/L), Civil Lines (826.66 mg/L), CFT (757.33 mg/L), Mumfordganj (662.66 mg/L), and Jhunsi (518 mg/L) exceed the permissible limit of 500 mg/L (IS 10500). TS levels show a strong positive correlation with total hardness and a significant negative correlation with both pH and alkalinity.

Table 11: The following table shows level of TS in different water samples of tap water

Graph10: The following graph shows level of TS in different water samples of tap water

11. Nitrates

Nitrate levels in Allahabad district range from 8.71 mg/L to 122 mg/L. Areas such as Civil Lines (122 mg/L), Daraganj (101.6 mg/L), Mumfordganj (89.1 mg/L), and CFT (61 mg/L) exceed the permissible limit of 45 mg/L (IS 10500). High nitrate levels in drinking water can cause health issues, particularly blue baby syndrome in infants and thyroid cancer. Nitrate sources include the nitrogen cycle, industrial waste, and nitrogenous fertilizers.^[24]

Table 12: The following table shows level of Nitrates in different water samples of tap water

Graph11: The following graph shows level of Nitrate in different water samples of tap water

12. Nitrite

Nitrite was detected in the drinking water sample from Daraganj (Allahabad district) at a level of 12.89 mg/L. No nitrite was found in samples from other areas.

Table 13: The following table shows level of Nitrite in different water samples of tap water

Graph12: The following graph shows level of Nitrite in different water samples of tap water

Data Sample description

Table 14: Sample data description table

13. Lead

The lead levels in different areas of Allahabad district range from 6.03 µg/L to 41.7 µg/L. Water samples from certain areas, including Daraganj (41.7 µg/L), Civil Lines (23.33 µg/L), Jhunsi (21 µg/L), Beli (17.33 µg/L), Mumfordganj (14.7 µg/L), and CFT (12.7 µg/L), exceeded the permissible limit of 0.01 mg/L according to drinking water specifications (IS 10500). High levels of lead in drinking water can cause serious health issues, such as cancer, ADHD in children, and damage to the brain, red blood cells, and kidneys.^[25] The risks are especially high for young children and pregnant women.

Table 15: The following table shows level of Lead in different water samples of tap water

Graph13: The following graph shows level of Lead in different water samples of tap water

14. Arsenic

Arsenic is a known carcinogen, and millions of people are exposed to it through drinking water. At high concentrations, it poses significant health risks, including cancer.^[26] The permissible limit for arsenic in drinking water, as per IS 10500, is 0.01 µg/L. However, arsenic was not detected in any of the water samples from the Allahabad region.

Table 16: The following table shows level of Arsenic in different water samples of tap water

The study of drinking water quality in various regions of Allahabad district highlighted several concerns regarding water safety and the adherence to the permissible standards set by IS 10500. Water samples were collected from different areas including Beli, Phaphamau, Daraganj, Mumford Ganj, Civil Lines, Jhunsi, and CFT, and were analyzed for a range of physicochemical parameters. While parameters like pH and chloride were found within permissible limits, other critical indicators such as alkalinity, hardness, total solids, total dissolved solids (TDS), lead, and nitrate exceeded the acceptable thresholds in some areas.

The presence of elevated levels of total solids, TDS, alkalinity, and hardness suggests significant water quality issues in these regions, which could be attributed to improper water management, increasing urbanization, and lack of adequate water treatment practices. These parameters are indicative of high mineral content, which can affect the taste, safety, and suitability of water for consumption. Moreover, the detection of nitrate and nitrite in the water raises concerns about potential health risks, including methemoglobinemia (blue baby syndrome) and thyroid cancer. Lead contamination found in some areas of Allahabad, with concentrations exceeding permissible limits, is of particular concern. Lead exposure is associated with an increased risk of anxiety and metabolic disorders, including dyslipidemia, which is a significant predictor of chronic conditions like obesity. Metabolites indicative of poor metabolic health could serve as potential biomarkers for anxiety.^[27] Exposure to lead is linked to serious health issues such as developmental disorders in children, ADHD, and increased cancer risk.^[28] The presence of such contaminants further underscores the urgent need for effective water quality monitoring and treatment measures to safeguard public health.

The quality of drinking water in Allahabad district is a growing concern, with several regions showing elevated levels of key contaminants that exceed the permissible limits set by IS 10500. While some parameters like pH and chloride were within acceptable ranges, other factors such as alkalinity, hardness, total solids, lead, and nitrate were found to be hazardous to human health, indicating the need for improved water management practices. This study highlights the need for pre-treatment of drinking water in Allahabad to ensure its safety and prevent future health complications. Ongoing monitoring and improved water management strategies are crucial to ensure that drinking water remains safe for consumption. Implementing stringent water quality standards and enhancing public awareness about water contamination are essential steps toward safeguarding public health.

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