This study covers the purification and sterilization stations in different regions of the Iraqi city of Baghdad. To systematically conduct this study, several drinking water samples were collected from various sites in Al-Karkh and Al-Rusafa in Baghdad. These samples were tested bacteriologically, such as Bacterial Total Count, Total Coliform Bacteria, fecal bacteria, and Escherichia coli (E. coli). Furthermore, the physical properties of the total hardness (TH), turbidity, residual chlorine, and pH from June 2021 to July 2022 were measured monthly. The seasonal variation of the research parameters is considered by providing a statistical description. The biological tests indicate that the water is seriously contaminated with fecal coliform in one area of the Al-Karkh region during the months of autumn and summer. Also, the biological tests of the Al-Rusafa region elucidate the dangerous concentrations of plate count bacteria in summer and autumn. Furthermore, the Al-Rusafa region reports cases of E. coli and coliform in the summer, which exceed the Iraqi and WHO guidelines. But, the physical tests ascertain the semi-alkalinity of drinking water with the greatest residual chlorine value of 0.9 ppm in the summer.

  • The drinking water is semi-alkaline to neutral.

  • The residual chlorine is within the Iraqi and WHO standards.

  • The turbidity values are within the allowed limit of 5 Nephelometric Turbidity Unit (NTU).

  • The water is seriously contaminated with fecal coliform in one area of Al-Karkh in autumn and summer.

  • The biological examinations of the Al-Rusafa region reveal high dangerous concentrations of plate count bacteria during summer and autumn.

The most vital element on the planet for maintaining life is water. Water is the essence of life without which life cannot exist. All living things, including people, animals, and plants, need it as a fundamental component of all life functions. Water is a universal solvent that will dissolve a variety of pollutants and compounds. Around the world, 1.1 billion individuals drink water that has been contaminated, whether consciously or unconsciously. Drinking water contaminants can have low or high quantities, which can directly or indirectly affect public health (Sabeeh et al. 2023).

Because of growing resource usage, climatic change, and population growth, freshwater is presently viewed as a restricted resource in many regions of the world (Jia et al. 2019). The greatest challenges in the majority of developing nations are overcoming water shortages, protecting water bodies from pollution, and observing physical and biological aspects of water bodies to assure clean water and ideal aquatic life (Abbas & Hassam 2018). Water quality is impacted by a growth in anthropogenic activity, and any physical or chemical pollution would affect the quality of the water sources (Aremu et al. 2011). Citizens must receive freshwater from the water-purifying stations. Undoubtedly, it is crucial to use cutting-edge water treatment and sterilization techniques, which notably guaranteed a decline in the mortality rate from polluted drinking water (Jafarzadeh et al. 2017; Al-hotmani et al. 2020; Ansari et al. 2021).

The concentrations of the composition, which determine the quality of drinking water, indicate whether water is potable or not. Both natural and man-made processes have an effect on the water quality. In this sense, the physical, chemical, and microbiological criteria can be used to characterize the water quality. Certainly, the health of people would be seriously jeopardized if these parameters exceeded the tolerable and national guideline limits of WHO (2012). In other words, drinkable water must meet WHO requirements for microbiological, chemical, and physical characteristics. The absence of coliform bacteria in 100 mL samples of water is required for safe drinking water, while their existence in drinking water suggests the presence of potentially harmful bacteria (Some et al. 2021). The recommendations state that water of less than 5 Nephelometric Turbidity Unit (NTU) turbidity can be safe in terms of the physio-chemical quality of drinking water (Chalchisa et al. 2018). As indicated by occurrences of waterborne illnesses in both rural and urban regions, water quality is increasingly becoming a concern.

The most challenging issues in the majority of developing nations are the lack of water and how to protect water sources from water contamination, in addition to keeping an eye on the biological and physical characteristics of water bodies. Specifically, it is a crucial scheme for preserving both public health and aquatic life. The sophisticated water desalination facilities are specifically in charge of giving the public safe water. Due to the significance of determining the quality of drinking water as an indicator of water use. This study aims to evaluate drinking water quality of the purification and sterilization stations in the city of Baghdad, Iraq by conducting various biological and physical tests of collected water samples. Drinking water samples were specifically taken from various locations in Al-Karkh and Al-Rusafa in Baghdad monthly from June 2021 to July 2022. This, in turn, has assured the seasonal change of the studied parameters, which are analyzed by a statistical procedure.

Study area and key concerns

Baghdad is the capital city of Iraq, located in the central part of the country on the eastern bank of the Tigris River. It is one of the largest cities in the Middle East with more than 8 million people.

The primary drinking water source in Baghdad is the Tigris River. Municipalities in Baghdad are in charge of producing and delivering drinking water, which are located in the main two regions of Bagdad, Al-Karkh and Al-Rusafa. Due to the increased and indirect disposal of municipal and pharmaceutical wastewater into the Tigris River, several scholars carried out systematic evaluations of drinking water in Baghdad. Ghafil et al. (2022) conducted chemical and bacteriological tests on drinking water in Baghdad in 2022 and indicated that the collected samples have no pollutants and the concentrations do not exceed the acceptable limits. Thus, many projects of bottled drinking water were constructed in Iraq besides manufacturing home water purification and disinfection systems for improving setup and freshwater desalination systems (Salehi et al. 2018).

Drinking water samples

Drinking water samples were taken from the research region every month between June 2021 and July 2022 in order to perform physical and bacteriological examinations. Specifically, the water samples were taken from the Al-Karkh and Al-Rusafa regions. In this aspect, the water samples under evaluation were collected from three districts of Al-Kadhimiya, Al-Taji, and Al-Shula of Al-Karkh region. Also, the water samples were collected from three districts of Al-Shaab, Al-Salikh, and Al-Adhamiy of the Al-Rusafa region. Table 1 depicts the details of covered stations.

Table 1

Details of the covered stations in the city of Baghdad

Station nameLocation in Baghdad cityStation coordinates
Al-Khadmia Al-Karkh region 33.380244, 44.341957 
Al-Ttagi 33.500161, 44.257777 
Al-Shoalla 33.361732, 44.285330 
Al-Slekh Al-Rusafa region 33.391843, 44.379498 
Al-Aadhmia 33.368637, 44.359081 
Al-Shaab 33.412670, 44.399475 
Station nameLocation in Baghdad cityStation coordinates
Al-Khadmia Al-Karkh region 33.380244, 44.341957 
Al-Ttagi 33.500161, 44.257777 
Al-Shoalla 33.361732, 44.285330 
Al-Slekh Al-Rusafa region 33.391843, 44.379498 
Al-Aadhmia 33.368637, 44.359081 
Al-Shaab 33.412670, 44.399475 

Bacteriological examination samples

Bacterial Total Count

The Bacterial Total Count test (BTCT) is a preliminary estimation method to define the microbial load in various samples. This estimation method is widely used to assure the quality control and environmental metrics and to secure the food and water safety. Specifically, the BTCT is used to measure the bacterial colonies in a particular collected sample. Further details of the BTCT can be found in Rice & Bridgewater (2012). To systematically conduct this test, each sample was diluted in a series of dilution tubes using a sterile diluent, a buffered saline solution. About l mL of solution was then transferred to sterile glass dishes from the final dilutions while conducting three repetitions. Thus, aliquots of the diluted sample were utilized or poured into sterilized agar plates after being diluted. The inoculated agar plates were then incubated for a prearranged period between 24 and 48 h while maintaining a fixed temperature of 37 °C. In this regard, the bacterial colonies were developed and became obvious colonies on the agar surface during this period. The plates were examined in person after incubation, and the number of bacterial colonies was calculated and reported as one colony-forming per 100 mL based on the dilution parameters.

Assay for Total Coliform Bacteria

The assessment of water quality involves the microbiological test used that identifies the Assay for Total Coliform Bacteria (TC). It acts as a central warning sign for potential pollution, specifically in drinking water systems. The coliform bacteria are considered as a class of microorganisms that contains humans and other warm-blooded creatures. They are identified by this assay (Pal 2014). A water sample is cultured as part of the test using a selective medium that is projected to enhance the growth of coliform bacteria. The existence of colonies depicts that the water source is possibly contaminated after incubation. The Assay for TC is important for defining if water is microbiologically safe and satisfies the requirements for human consumption. This technology necessitates recurrent and detailed testing, which is necessary for avoiding waterborne illnesses and protecting public health.

Thermotolerant (fecal) bacteria of the coliform type

Thermotolerant (fecal) coliform bacteria are employed as a measure of water quality. Thermotolerant coliforms, which can resist higher temperatures than other coliform bacteria, are a superior sign of fecal contamination, principally in tropical and subtropical regions where water temperatures are high (Pachepsky et al. 2016). These microorganisms. including Escherichia coli. frequently occur in the intestines of warm-blooded creatures, including human, and their occurrence in water advocates that it may have been contaminated by feces. It is probable to ascertain thermotolerant coliforms by selectively recognizing them in water samples that have been incubated at high temperatures.

E. coli screening

E. coli screening is a straightforward microbiological test to define the safety water. A vital sign of fecal contamination is the attendance of the bacterium E. coli, which typically arises in the intestines of warm-blooded mammals like humans. E. coli is not certainly present in freshwater as it fundamentally lives in the intestinal tract. However, E. coli infection in water samples proposes the opportunity of fecal matter contamination, representing the probable survival of dangerous pathogens (Odonkor & Ampofo 2013). Particular tests that focus on the distinctive genetic and biochemical traits of E. coli are used for testing. The importance of E. coli screening is highlighted by the need for rapid and precise screening technologies for the early detection and avoidance of waterborne infections.

Test of total hardness

The total hardness (TH) of a sample was determined using titrating disodium ethylene diamine tetra acetic acid (EDTA) with the water sample and using an indicator of Erichrome B-T (EBT). About 2 mL of buffer solution was added to the samples using a pipette. Eight drops of the EBT indicator were added to the 100 mL of water samples in the conical flasks using a dropping pipette, and the samples turned wine-red. After that, the samples were titrated with a 0.010 M standard EDTA solution until the color changed from wine-red to pure. The temperature of the water was measured by immersing a thermometer in water for 5 min. The results are given in Celsius degrees.

Turbidity test

Turbidity was measured using a digital portable turbidity meter manufactured by the American company's device (HACH). The device of a scale (100–1,000) was used to measure the turbidity of drinking water samples in NTU.

Residual chlorine test

The DPD (N,N-diethyl-1,4-phenylendiamin) detector was utilized to measure the residual chlorine of water samples using the Lovi Bond Comparator device. These changes were detected by visual color comparison or photometric measurement.

pH test

pH was determined immediately during sample collection using the GLP pH/ORP meter HANNA HI 98150 (Romania) portable device.

Data processing and statistical analysis

The data processing and statistical analyses were conducted using the variance test (ANOVA) to find out a significant difference in the biological and physical parameter of the stations under investigation. The correlation test was used to evaluate the relationships between different parameters.

Biological parameters

The bacteriological analysis sought to determine whether E. coli, coliforms, plate counts, and fecal coliforms are presented beyond the standards. Tables 2 and 3 show the associated results of the bacteriological examination of the drinking water samples collected from Al-Karkh and Al-Rusafa regions in different seasons between June 2021 and July 2022.

Table 2

Seasonal variation of the biological parameters of the Al-Karkh region

RegionSeasonsPlate count /100 mLFecal coliform /100 mLE. coli /100 mLColiform /100 mL
Al-Khadmia Summer 
Al-Ttagi 
Al-Shoalla 
Al-Khadmia Autumn 
Al-Ttagi 
Al-Shoalla 
Al-Khadmia Winter 
Al-Ttagi 
Al-Shoalla 
Al-Khadmia Spring 
Al-Ttagi 
Al-Shoalla 
Maximum allowed the concentration of the Iraqi guideline 10 
Maximum allowed the concentration of the WHO guideline 1 to 3 
RegionSeasonsPlate count /100 mLFecal coliform /100 mLE. coli /100 mLColiform /100 mL
Al-Khadmia Summer 
Al-Ttagi 
Al-Shoalla 
Al-Khadmia Autumn 
Al-Ttagi 
Al-Shoalla 
Al-Khadmia Winter 
Al-Ttagi 
Al-Shoalla 
Al-Khadmia Spring 
Al-Ttagi 
Al-Shoalla 
Maximum allowed the concentration of the Iraqi guideline 10 
Maximum allowed the concentration of the WHO guideline 1 to 3 
Table 3

Seasonal variation of the biological parameters of the Al-Rusafa region

RegionSeasonsPlate count /100 mLFecal coliform /100 mLE. coli /100 mLColiform /100 mL
Al-Slekh Summer 11 
Al-Aadhmia 38 35 28 
Al-Shaab 38 35 32 
Al-Slekh Autumn 23 30 40 41 
Al-Aadhmia 
Al-Shaab 30 15 20 22 
Al-Slekh Winter 20 33 22 
Al-Aadhmia 
Al-Shaab 
Al-Slekh Spring 
Al-Aadhmia 
Al-Shaab 
Maximum allowed the concentration of the Iraqi guideline 10 
Maximum allowed the concentration of the WHO guideline 1 to 2 
RegionSeasonsPlate count /100 mLFecal coliform /100 mLE. coli /100 mLColiform /100 mL
Al-Slekh Summer 11 
Al-Aadhmia 38 35 28 
Al-Shaab 38 35 32 
Al-Slekh Autumn 23 30 40 41 
Al-Aadhmia 
Al-Shaab 30 15 20 22 
Al-Slekh Winter 20 33 22 
Al-Aadhmia 
Al-Shaab 
Al-Slekh Spring 
Al-Aadhmia 
Al-Shaab 
Maximum allowed the concentration of the Iraqi guideline 10 
Maximum allowed the concentration of the WHO guideline 1 to 2 

Referring to the maximum allowed concentration of the Iraqi and WHO guidelines, Table 2 ascertains the unsatisfactory and highly contaminated water with fecal coliform in summer and autumn in Altagi in Alkarkh. Additionally, there is an increase of E. coli in summer to 1 E. coli per 100 mL. However, the water samples of the Al-Khrakh region are not contaminated with plate count bacteria and coliform since the concentrations are within the Iraqi drinking water guideline. The water samples from Al-Shoalla in the Al-Khrakh region, however, can assign elevated concentrations beyond the WHO-allowed limit in the spring and obtained the maximum value in the winter.

Table 3 shows that the water samples from the Al-Rusafa region have critical concentrations of plate count bacteria that exceed the acceptable limit of WHO. This occurs throughout the tested seasons, especially in Al-Selekh and Al-Shaab during summer and autumn. Furthermore, the fecal coliform, E. coli, and coliform concentrations of the freshwater samples of all the tested districts of the Al-Rusafa region (Al-Slekh, Al-Aadhmia, and Al-Shaab) have significantly increased beyond the standards. This is a remarkable warning sign of a persistent contamination of drinking water in the Al-Rusafa region, especially in summer and autumn. Broken water pipelines, over-flowing sewage, open defecation, rusted pipelines, and poor maintenance of pipe networks are the main reasons of contaminated water. Furthermore, the industry and agriculture anthropogenic activities close to water bodies attribute to polluted water. This issue is specifically worsened in high populated regions, especially in unplanned urban cities (Saeed et al. 2022). The recognition of E. coli in freshwater samples is a proof of fecal contamination and the probable presence of pathogenic microbes (Farooqi et al. 2020). Cabral (2010) stated that the fecal coliform in drinking water can lead to an exposure of specific pathogenic microorganisms, which can be attributed to the contamination of source water with domestic wastewater. Thus, the dependence of such water sources for freshwater must be sidestepped.

Physical parameters

Temperature

Temperature impacts the rate of chemical reactions in the water sources and is critical to the survival of microorganisms. During summer, the greatest registered temperature in water was 31.5 °C in the Al-Shoalla region in Al-Karkh (Table 4). The fecal coliforms in storage tanks have been increased due to the high temperature. Wille (2019) noted the growth of favored bacteria at high water temperatures. On the other hand, the lowest water temperature of 10 °C is registered in the Al-Khadmia region in winter (Table 4).

Table 4

Seasonal variation of the physical parameters of the Al-kharkh region

RegionSeasonTurbidityResidual Cl2pHTemperatureTH
NTUmg/L(–)°Cmg/L
Al-Khadmia Summer 1.21 0.3 7.99 29.7 350 
Al-Ttagi 3.1 0.61 8.2 30.2 320 
Al-Shoalla 1.18 0.32 8.09 31.5 315 
Al-Khadmia Autumn 2.2 0.9 7.98 22 388 
Al-Ttagi 3.2 0.75 7.77 21.3 379 
Al-Shoalla 1.15 0.32 7.92 20.2 392 
Al-Khadmia Winter 1.12 0.42 7.3 10 440 
Al-Ttagi 1.5 0.52 7.2 10.9 451 
Al-Shoalla 2.3 0.32 7.25 11.4 461 
Al-Khadmia Spring 4.1 0.4 7.62 19.5 402 
Al-Ttagi 3.1 0.8 7.67 20 409 
Al-Shoalla 3.8 0.4 7.44 17.6 414 
Maximum allowed the concentration of the Iraqi guideline (0.3–2.0) (6.5–8.5) – >500 
Maximum allowed the concentration of the WHO guideline (0.3–2.0) (6.5–8.5) – >500 
RegionSeasonTurbidityResidual Cl2pHTemperatureTH
NTUmg/L(–)°Cmg/L
Al-Khadmia Summer 1.21 0.3 7.99 29.7 350 
Al-Ttagi 3.1 0.61 8.2 30.2 320 
Al-Shoalla 1.18 0.32 8.09 31.5 315 
Al-Khadmia Autumn 2.2 0.9 7.98 22 388 
Al-Ttagi 3.2 0.75 7.77 21.3 379 
Al-Shoalla 1.15 0.32 7.92 20.2 392 
Al-Khadmia Winter 1.12 0.42 7.3 10 440 
Al-Ttagi 1.5 0.52 7.2 10.9 451 
Al-Shoalla 2.3 0.32 7.25 11.4 461 
Al-Khadmia Spring 4.1 0.4 7.62 19.5 402 
Al-Ttagi 3.1 0.8 7.67 20 409 
Al-Shoalla 3.8 0.4 7.44 17.6 414 
Maximum allowed the concentration of the Iraqi guideline (0.3–2.0) (6.5–8.5) – >500 
Maximum allowed the concentration of the WHO guideline (0.3–2.0) (6.5–8.5) – >500 

pH

Table 4 illustrates the pH values of the drinking water samples of the tested stations, which range between 7.2 and 8.2, indicating that the water samples range from semi-alkaline to neutral. Indeed, the Iraqi standard limit of pH is 6.5–8.5.

Turbidity

Turbidity is a crucial factor since it has an impact on whether water is potable or not. Tables 4 and 5 show that the turbidity of drinking water of Al-Kharkh and Al-Rusafa stations is lower than the maximum permissible value of 5 NTU. However, the drinking water of Al-the Kharkh station is more turbid than that of the Al-Rusafa station. The turbidity is a consequence of inert clay and chalk and insoluble particles and probably changes as a result of surrounding region surface runoff, river hydrology, amortized water supply network, human activity, and land use (de Bastos et al. 2021). This would interpret the variation of turbidity throughout the four seasons in Al-Kharkh and Al-Rusafa stations. In spring, the greatest value of turbidity has been identified in the drinking water of the Al-Kharkh station. This can, therefore, refer to a low-quality water filtration process in this season.

Table 5

Seasonal variation of the physical parameters of the Al-Rusafa region

RegionSeasonTurbidityResidual Cl2pHTemperatureTH
NTUmg/L(–)°Cmg/L
Al-Slekh Summer 1.1 0.8 8.1 31.5 366 
Al-Aadhmia 1.3 7.92 29.3 358 
Al-Shaab 1.4 8.2 30.2 344 
Al-Slekh Autumn 1.3 0.2 7.6 22 388 
Al-Aadhmia 1.31 0.78 7.66 23 379 
Al-Shaab 1.82 0.1 7.5 23.9 392 
Al-Slekh Winter 2.1 7.4 12 434 
Al-Aadhmia 1.18 0.5 7.3 12.2 455 
Al-Shaab 1.1 0.5 7.42 11.2 488 
Al-Slekh Spring 1.2 0.4 7.8 20.2 410 
Al-Aadhmia 1.4 0.35 7.59 19.8 408 
Al-Shaab 1.28 0.3 7.89 18.7 412 
Maximum allowed the concentration of the Iraqi guideline (0.3–2.0) (6.5–8.5) – >500 
Maximum allowed the concentration of the WHO guideline (0.3–2.0) (6.5–8.5) – >500 
RegionSeasonTurbidityResidual Cl2pHTemperatureTH
NTUmg/L(–)°Cmg/L
Al-Slekh Summer 1.1 0.8 8.1 31.5 366 
Al-Aadhmia 1.3 7.92 29.3 358 
Al-Shaab 1.4 8.2 30.2 344 
Al-Slekh Autumn 1.3 0.2 7.6 22 388 
Al-Aadhmia 1.31 0.78 7.66 23 379 
Al-Shaab 1.82 0.1 7.5 23.9 392 
Al-Slekh Winter 2.1 7.4 12 434 
Al-Aadhmia 1.18 0.5 7.3 12.2 455 
Al-Shaab 1.1 0.5 7.42 11.2 488 
Al-Slekh Spring 1.2 0.4 7.8 20.2 410 
Al-Aadhmia 1.4 0.35 7.59 19.8 408 
Al-Shaab 1.28 0.3 7.89 18.7 412 
Maximum allowed the concentration of the Iraqi guideline (0.3–2.0) (6.5–8.5) – >500 
Maximum allowed the concentration of the WHO guideline (0.3–2.0) (6.5–8.5) – >500 

Residual chlorine

Due to its widespread availability and affordable price in most parts of the world, chlorine is one of the most commonly used sterilizers for destroying bacteria and oxidizing a number of pollutants that contaminate drinking water (Al-Sa'ady et al. 2020). In other words, the concentration of residual chlorine limits the growth of microorganisms and bacteria.

The measurements indicate a clear difference in residual chlorine values of drinking water for the four seasons of the selected regions in Baghdad. Specifically, the greatest chlorine concentration of 0.9 mg/L has been registered during the autumn in the Al-Khadmia districts of the Al-Karkh region. But the Al-Selekh district of the Al-Rusafa region records the lowest chlorine level of 0.2 mg/L (Table 4). More importantly, the 0.2 mg/L is proof of the residual chlorine below the regulations of Iraq and WHO. In this regard, the highest residual chlorine of drinking water was found in autumn and summer in Al-Kharkh region and Al-Rusafa regions, respectively, compared to winter. This is attributed to the inverse relationship between residual chlorine and temperature where the dissolution of chlorine increases with the increase in temperature. As a result, higher than normal residual chlorine levels are to be expected during the hotter months, which need to be addressed to guarantee that the water is safe to drink. The results on the microbiology of the current study are in agreement with the findings of Bondank et al. (2018) and Salehi et al. (2018).

Total hardness

In addition to polyvalent salts like those of iron, manganese, and aluminum, hard water also contains calcium and magnesium salts. According to the current study, the highest and lowest values of TH are 488 mg/L in the springtime in the Al-Shaab region and 315 mg/L in the summertime in the Al-Shoalla region (Tables 4 and 5).

Statistical analysis

The statistical description of the biological and physical parameters is represented in Table 6, which includes the minimum, maximum, and mean seasonally values. Specifically, the temperature can positively affect the increase of fecal coliform by a significant correlation besides the possible of bacterial contamination due to an increase in the TH. Table 6 shows consistent relationships between the biological parameters of plate count bacteria, fecal coliform, E. coli and coliform and their negative relationships with residual chlorine. Furthermore, Table 6 indicates a significant correlation between pH and temperature and TH.

Table 6

Correlation among parameters

Correlations
Plate countFecal coliformE. coliColiformTurbidityCl2pHTemperatureTH
Plate count r 0.464* 0.565* 0.674* 0.419* −0.405* −0.022 0.336 −0.336 
Fecal coliform r 0.464* 0.953** 0.936** 0.311 −0.768** 0.327 0.452* −0.540* 
E. coli r 0.565* 0.953** 0.972** 0.486* −0.788** 0.134 0.289 −0.428* 
Coliform r 0.674* 0.936** 0.972** 0.419* −0.750** 0.167 0.371 0.489* 
Turbidity r 0.419* 0.311 0.486* 0.419* −0.608* −0.315 −0.174 −0.023 
Cl2 r −0.405* −0.768** −0.788** −0.750** −0.608* −0.029 −0.043 0.186 
pH r −0.022 0.327 0.134 0.167 −0.315 −0.029 0.839** −0.782** 
Temperature r 0.336 0.452* 0.289 0.371 −0.174 −0.043 0.839** −0.942** 
TH r −0.336 −0.540* −0.428* −0.489* −0.023 0.186 −0.782** −0.942** 
Correlations
Plate countFecal coliformE. coliColiformTurbidityCl2pHTemperatureTH
Plate count r 0.464* 0.565* 0.674* 0.419* −0.405* −0.022 0.336 −0.336 
Fecal coliform r 0.464* 0.953** 0.936** 0.311 −0.768** 0.327 0.452* −0.540* 
E. coli r 0.565* 0.953** 0.972** 0.486* −0.788** 0.134 0.289 −0.428* 
Coliform r 0.674* 0.936** 0.972** 0.419* −0.750** 0.167 0.371 0.489* 
Turbidity r 0.419* 0.311 0.486* 0.419* −0.608* −0.315 −0.174 −0.023 
Cl2 r −0.405* −0.768** −0.788** −0.750** −0.608* −0.029 −0.043 0.186 
pH r −0.022 0.327 0.134 0.167 −0.315 −0.029 0.839** −0.782** 
Temperature r 0.336 0.452* 0.289 0.371 −0.174 −0.043 0.839** −0.942** 
TH r −0.336 −0.540* −0.428* −0.489* −0.023 0.186 −0.782** −0.942** 

*: denotes a high significant correlation between parameters (p < 0.05).**: denotes a moderate significant correlation between parameters (p < 0.01).

Tables 7 and 8 show the influence of season on the biological and physical parameters in Al-Karkh and Al-Rusafa regions by introducing the mean and standard deviation. The statistical analysis of Table 7 represents no significant difference in bacterial contamination including the plate count, fecal coliform, E. coli, and coliform due to having different seasons of variable temperatures. Specifically, having the same letter (a) means in the first rows of Table 7 means no significant change. However, the physical parameters (except the residual chlorine) are affected by the season, with significant changes on the pH, temperature, and TH.

Table 7

Mean and standard deviation of studied parameters of four seasons of the Al-Karkh region

ParametersSeasons
SummerAutumnWinterSpring
Plate count 4.00 ± 1.000a 2.33 ± 1.528a 3.33 ± 1.528a 4.00 ± 2.646a 
Fecal coliform 0.33 ± 0.577a 0.67 ± 1.155a 0.00 ± 0.000a 0.00 ± 0.000a 
E. coli 0.33 ± 0.577a 0.00 ± 0.000a 0.00 ± 0.000a 0.00 ± 0.000a 
Coliform 0.67 ± 1.155a 0.00 ± 0.000a 0.00 ± 0.000a 0.00 ± 0.000a 
Turbidity 1.830 ± 1.099c 2.183 ± 1.025b,c 1.640 ± 0.602c 3.666 ± 0.513a 
Residual Cl2 0.410 ± 0.173a 0.656 ± 0.301a 0.420 ± 0.100a 0.533 ± 0.230a 
pH 8.093 ± 0.105a 7.890 ± 0.108b 7.250 ± 0.050c 7.576 ± 0.120d 
Temperature 30.467 ± 0.929a 21.167 ± 0.907b 10.767 ± 0.709d 19.033 ± 1.266c 
TH 328.33 ± 18.930d 386.33 ± 6.658c 450.67 ± 10.504a 408.33 ± 6.028b 
ParametersSeasons
SummerAutumnWinterSpring
Plate count 4.00 ± 1.000a 2.33 ± 1.528a 3.33 ± 1.528a 4.00 ± 2.646a 
Fecal coliform 0.33 ± 0.577a 0.67 ± 1.155a 0.00 ± 0.000a 0.00 ± 0.000a 
E. coli 0.33 ± 0.577a 0.00 ± 0.000a 0.00 ± 0.000a 0.00 ± 0.000a 
Coliform 0.67 ± 1.155a 0.00 ± 0.000a 0.00 ± 0.000a 0.00 ± 0.000a 
Turbidity 1.830 ± 1.099c 2.183 ± 1.025b,c 1.640 ± 0.602c 3.666 ± 0.513a 
Residual Cl2 0.410 ± 0.173a 0.656 ± 0.301a 0.420 ± 0.100a 0.533 ± 0.230a 
pH 8.093 ± 0.105a 7.890 ± 0.108b 7.250 ± 0.050c 7.576 ± 0.120d 
Temperature 30.467 ± 0.929a 21.167 ± 0.907b 10.767 ± 0.709d 19.033 ± 1.266c 
TH 328.33 ± 18.930d 386.33 ± 6.658c 450.67 ± 10.504a 408.33 ± 6.028b 

Similar letters mean no statistical significance between seasons different letters mean statistical significance between seasons.

Table 8

Mean and standard deviation of studied parameters of four seasons of the Al-Rusafa region

ParametersSeasons
SummerAutumnWinterSpring
Plate count 9.33 ± 1.528b 18.00 ± 15.133a 4.00 ± 3.464c 3.00 ± 1.000c 
Fecal coliform 26.33 ± 20.207a 15.00 ± 15.000b 7.67 ± 10.786c 0.67 ± 1.155c 
E. coli 24.00 ± 19.053a 20.00 ± 20.000a 12.00 ± 18.248a 0.00 ± 0.000a 
Coliform 21.00 ± 15.716a 21.00 ± 20.518a 7.33 ± 12.702a 1.67 ± 2.887a 
Turbidity 1.266 ± 0.152a 1.476 ± 0.297a 1.460 ± 0.555a 1.293 ± 0.100a 
Cl2 0.266 ± 0.461a 0.360 ± 0.367a 0.333 ± 0.288a 0.350 ± 0.050a 
pH 8.073 ± 0.141a 7.587 ± 0.080b 7.373 ± 0.064c 7.760 ± 0.153b 
Temperature 30.333 ± 1.106a 22.967 ± 0.950b 11.800 ± 0.529d 19.567 ± 0.776c 
TH 356.00 ± 11.136d 386.33 ± 6.658c 459.00 ± 27.221a 410.00 ± 2.000b 
ParametersSeasons
SummerAutumnWinterSpring
Plate count 9.33 ± 1.528b 18.00 ± 15.133a 4.00 ± 3.464c 3.00 ± 1.000c 
Fecal coliform 26.33 ± 20.207a 15.00 ± 15.000b 7.67 ± 10.786c 0.67 ± 1.155c 
E. coli 24.00 ± 19.053a 20.00 ± 20.000a 12.00 ± 18.248a 0.00 ± 0.000a 
Coliform 21.00 ± 15.716a 21.00 ± 20.518a 7.33 ± 12.702a 1.67 ± 2.887a 
Turbidity 1.266 ± 0.152a 1.476 ± 0.297a 1.460 ± 0.555a 1.293 ± 0.100a 
Cl2 0.266 ± 0.461a 0.360 ± 0.367a 0.333 ± 0.288a 0.350 ± 0.050a 
pH 8.073 ± 0.141a 7.587 ± 0.080b 7.373 ± 0.064c 7.760 ± 0.153b 
Temperature 30.333 ± 1.106a 22.967 ± 0.950b 11.800 ± 0.529d 19.567 ± 0.776c 
TH 356.00 ± 11.136d 386.33 ± 6.658c 459.00 ± 27.221a 410.00 ± 2.000b 

Similar letters mean no statistical significance between seasons different letters mean statistical significance between seasons.

In the Al-Rusafa region, Table 8 depicts the influence of season on the concentration of plate count and fecal coliform bacteria, besides having no effect on E. coli and coliform. This can be ascribed to the influx of fecal pollution that can increase as a result of rainfall. The feces of domestic animals and polluted soils are effortlessly washed into rivers by rain, causing a growth in bacterial contamination. However, this effect can be mitigated in the dry season, where less rainfall can reduce the contaminated water. Except for turbidity and residual chlorine, the rest of physiological parameters have witnessed changes throughout the seasons.

Due to pH readings that are lower than the Iraqi regulatory limit of 8.5, the results of physical properties determine that the drinking water is semi-alkaline to neutral. In comparison to 0.2 ppm in the autumn, the summer has the greatest residual chlorine value of 0.9 ppm. It was found that the measured turbidity is between 1.1 and 4.1 NTU, which is consequently within the allowed limits of 5 NTU. Also, the biological tests revealed that in one area of Al-Karkh in the autumn and summer months, the water is seriously contaminated with fecal coliform. It is interesting to note that the water samples from Al-Karkh, where they meet Iraqi and WHO standards, have not been found to be contaminated with plate count bacteria. During the summer and autumn seasons, water samples from the Al-Rusafa region had plate count bacteria concentrations that were higher than allowed ones. Also, the Al-Rusafa region in the summer, reported cases of E. coli and coliform that surpass the Iraqi and WHO International guidelines. The statistical analysis generates a number of correlations to define the connections between the temperature and the analyzed biological and physical characteristics.

The significance of this study is that it provides a comprehensive evaluation of the biological and physical parameters of drinking water in Baghdad, Iraq. This information can be used to classify areas where the water quality is poor. Accordingly, there is a necessity to develop strategies to enhance the water quality by upgrading the existed treatment plants or installing new treatment plants.

The authors have consented to publish this article.

All authors contributed to the study's conception and analysis. Material preparation and design were performed by F.A.A.A. and G.H.M. Analysis was carried out by D.S.A. and F.A.A.A. The first data of the manuscript were written by D.S.A. and all authors commented on previous versions of the manuscript. The final version was edited and proffered by M.A.Al-O. All the authors read and approved the final manuscript.

No funding was received for conducting this study.

All relevant data are included in the paper or its Supplementary Information.

The authors declare there is no conflict.

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