Groundwater is the most common source of drinking water in the Sindh province of Pakistan. About 70-80% population in Sindh province relies on groundwater resources in order to meet their drinking and other domestic needs [1]. However, this important source of drinking water has been contaminated by various factors including natural and anthropogenic activities [2]. Water is contaminated by factors such as overpopulation, urbanization, climate change; percolation of solid waste leachate to groundwater, mixing of untreated domestic and industrial wastewater with natural streams, etc. [3].

Although groundwater contamination is a matter of grave concern for the whole of Pakistan, groundwater quality in Sindh province is declining due to the unavailability of waste water treatment units; failure of sewerage systems; frequent floods; and overuse of agricultural excessive use of fertilizers for crops, over abstraction of aquifers, and other anthropogenic activities. Studies have revealed that the mixing of sewage with streams and the percolation of sewage from standing ponds to groundwater is the main cause of poor water quality in the Sindh province of Pakistan [4]. It has also been found that the chemical characteristics of groundwater have drastically changed in the Sindh province of Pakistan in the last two decades. Water in Sindh is found to have higher concentrations of EC, TDS, TH, Cl, As, and other heavy metals. That’s why the availability of safe drinking for residents of Sindh province is shrinking every year [6]. In this regard, this study was proposed to check the chemical characteristics of groundwater of Larkana city because in Larkana there is no other source of drinking than groundwater. Although many scholars already have done thorough research on the groundwater quality of Larkana, none have done detailed research on Larkana city. Previous research has been done on rural areas of Taluka Larkana, Ratodero, Dokri, and other parts, but an analysis of the water quality of the central part of Larkana including urban areas of district Larkana, was missing. Therefore, in this research fitness of drinking water in urban areas has been proposed to be studies.

Larkana is located in the North-Western part of the Sindh province of Pakistan as shown in Figure 1. According to census 2023, the population of Larkana city is about 1,784,453. Moreover, Larkana is one of the largest districts of Sindh province and is located on the right bank of the Indus River. This city is also famous due to having historical archaeological site the “Meon Jo Daro” located in Larkana. People in Larkana completely count on groundwater and citizens are compelled to drink poor water in the most part of Larkana. The reason behind this compulsion is that there is no other economical source of drinking water in Larkana nor the government is providing water through any subsidized water supply schemes in any part of Larkana. Secondly, due to the unavailability of any source of treatment of water, people find groundwater more suitable for drinking than rain or river water. The depth of the Water table in Larkana City varies from 50 feet to 110 feet. The depth of the water table depends upon the intensity of aquifers being recharged, therefore, in the western, southern, and northern parts of Larkana, the average depth of the water table is 100 feet, while in the eastern part of Larkana, the average depth of water table is 50 feet due to being nearer to the river that keeps aquifer filled every time. Studies have found that western, southern, and northern parts of Taluka Larkana are completely contaminated and water is not suit for drinking [7]. Water at the eastern part of Larkana is suitable because it is nearer to the river and the river keeps aquifers recharged throughout the year and reduces the chances of wastewater percolating into the groundwater. However, the eastern part of Larkana needs an extensive analysis of Arsenic contamination, because Arsenic is usually found in the river water.

In this study chemical parameters of drinking water such as pH, Calcium, Magnesium, Total hardness (TH), Chloride, Sodium, Iron, Nitrites, and Nitrates, were determined in each sample of groundwater to know the status of groundwater quality in Larkana city.

For analysis of groundwater samples total of forty (40) water samples were collected from different locations such as Ahsan Colony, Sachal Colony, QUEST student’s hostel, etc. within Larkana city. Samples were collected in a half-litre water bottle purchased from the water treatment plant in Hyderabad and bottles were used that were never used before. Samples were taken from hand pumps, taps, and electric motors. It is important to note that the pump was allowed to discharge water for a minute and the hand pump for each sample was purged before collection of samples. This was done to remove water available in the suction pipe and to collect fresh groundwater samples. Bottles were washed with the same water, the sample of which was being collected. This was done in order to avoid any external source of contamination in water. Later on, Samples were gathered, labelled with a proper code, and sealed before taking to the laboratory. All 40 samples were tested for pH, Calcium, Magnesium, Total hardness (TH), Chloride, Sodium, Iron, Nitrites, Sulfate, and Nitrates, which were determined in the laboratory at the University of Larkano.

For checking the pH value of water pH meter was used and for other parameters required methodology was used. The detailed process of testing is shown in Table1.

Tests for each sample were done following all standard methods. The results of each parameter of each sample were noted and compared with the permissible values recommended by the WHO, NEQS, and water quality standard developed by SEPA.

Results of individual parameters such as pH, Calcium, Magnesium, Total hardness (TH), Chloride, Sodium, Iron, Nitrites, Sulfate, and Nitrates were determined and matched with the recommended values of the WHO, NEQS, and SEPA (Sindh Environmental Protection Agency). It should be noted that the recommended values of NEQS and SEPA are a reflection of the recommended values of the WHO. Therefore, the results of all samples were compared to the recommended values of the WHO and that was considered a benchmark for knowing the overall quality of groundwater in Larkana city. The results of each parameter are discussed below.

Water is a crucial source of life. However, this precious element of life is contaminated by various factors such as over abstraction, urbanization etc. Therefore, research works are being to detect suitability of drinking water throughout the world. Sindh province of Pakistan is also grappling with the degrading quality of drinking water. Groundwater is the major source of drinking water in Sindh province, but this source is no more in its pure state. That’s’ why variety research are proposed for checking suitability of groundwater in Sindh province as well. This study was proposed to know true status of groundwater in Larkana city. Forty groundwater samples were randomly collected from random locations from taps, hand pumps, and motor pumps. Each sample was analysed for water quality parameter such as pH, Calcium, Magnesium, Total hardness (TH), Chloride, Sodium, Iron, Nitrites, Sulfate and Nitrates, were analysed. Overall, assessment water samples revealed that the concentration of pH was within the permissible limit. However, 26% of samples had chloride beyond the permissible limit, and 32% of samples had a concentration of Total Hardness (TH) above the desirable limits. Moreover, 6%, 23%, 29%, 92%, and 80%, of samples had a concentration of Nitrates, Nitrites, Sulfate, calcium, and magnesium respectively.

It is recommended that suitable treatment unit for water treatment should be introduced in larkana as soon as possible so that health of citizens should be protected on the priority basis.