Abstract

Water pollution due to rapid urbanization and industrialization has become a major issue of concern worldwide. Water plays a vital role in human life, but access to safe drinking water has become a scarce commodity nowadays due to drastically increasing water pollution. Thus, water-borne diseases have become a common health hazard. So, basic monitoring of water quality has been necessitated to observe the level of water pollution. The quality of drinking water is determined by its biological, chemical, and physical features. In this study, the physicochemical and bacteriological analyses of some drinking water sources of Jorhat town were carried out to ascertain their suitability for consumption and other domestic uses. The water samples were collected from different sites based on their use by the local people. The results obtained were compared with WHO potability parameters. The study revealed that most of the samples' physicochemical parameters were within the permissible limits except for nitrate, hardness, turbidity in a few samples, which were beyond the permissible limits. Moreover, one groundwater sample was found to contain arsenic which can be a serious health threat if untreated used for a prolonged period. The most probable number (MPN) count from the bacteriological study revealed coliforms in most of the samples. This may be due to poor sanitation and unawareness about personal hygiene and cleanliness. The presence of these bacteria in drinking water increases the risk of water-borne diseases and health issues. The study showed that not all the water samples were potable and fit for drinking as most of the parameters were beyond the permissible limits. Thus, the present investigation suggests that the collected sources' water needs urgent measures to control pollution and to aware the local people to treat the water before using it properly.

1. Introduction

Water, the fuel of life, is a precious gift of nature to humankind and millions of other species living on the earth ¹. The availability of good quality drinking water is of utmost importance for preventing various diseases ² as human health and water quality are closely associated ³. Naturally, water contains multiple components such as living/non-living, soluble/insoluble, organic/inorganic, and also, the quality varies with place and time. The contamination of water is directly associated with contamination of the environment ². People obtain water from both surface and groundwater sources ⁴. However, pollution of both surface and groundwater has increased gradually while rapid population growth and increasing living standards have resulted in greater demand for quality water. Both human and animal activities affect water quality ⁵. Thus, access to safe drinking water has become a severe health issue concern ^{4, 6}. Water health is dependent on its physicochemical properties and biological diversity ^{7, 8}. However, n terms of human health, the most dangerous form of pollution occurs when fecal contaminants like Escherichia coli enter the water supply, which is the causative agent of many diseases, from mild gastroenteritis severe dysentery, diarrhea, cholera, and typhoid, etc. ^{4, 9}. Therefore, potable water is tested for an indicator of human or animal waste known as coliform bacteria, a standard indicator of fecal contamination ^{4, 7, 8}. Also, total coliform (TC) and fecal coliform (FC) bacteria are commonly used as biological indicators for monitoring the quality of drinking and surface water.TC bacteria in water indicates the presence of possible disease-causing organisms. At the same time, FC is selected members of the coliform group are specific for the feces of warm-blooded animals are commonly used indicators of fecal contamination of water. Various human activities are responsible for the rise of the bacterial concentration in water ⁸. Environmental Protection Agency (EPA) suggested E. coli as a good indicator of fecal contamination than fecal coliform for evaluating safe potable water quality. As estimated by the WHO, more than 80% of disease in developing countries is caused by contaminated drinking water, inadequate sanitation, and poor hygiene. Therefore, water needs to comply with specific physicochemical and bacteriological standards before being considered safe for drinking ⁴. There is an increasing interest in the analysis of physicochemical and microbial load in drinking water ¹⁰. The objective of this study is to investigate the physicochemical and bacteriological parameters of some drinking water sources of Jorhat town, Assam (India) so that the data obtained from this preliminary investigation may provide some information on public health risks associated with the use of water of the sites considered in the study which was less explored till date.

2. Materials and Methods

Jorhat is an administrative district situated in the middle part of the Brahmaputra valley in the Indian state of Assam. Majuli bounds the district on the North, Nagaland on the South, Charaideo on the East, and Golaghat on the West. The district's geographical area is 2,851 square kilometers and lies between 25.7509º North latitudes and 94.2037ºEast longitudes. Bhogdoi, a tributary of the River Brahmaputra, flows through the town and other lesser streams such as Tocklai, Tarajan, and Jahkharijan. The average annual rainfall is 2,045 millimeters.

Water sources mainly used for human consumption and livestock watering were collected for the present study to assess the physico-chemical and bacteriological contamination. Water samples were collected from different open and closed water sources such as river, ponds and tube well around Jorhat town. A total of 10 sampling sites were selected namely:

Location 1: Tarajan pond

Location 2: Hindubari pond

Location 3:Tinikonia pond

Location 4:Bhogdai River

Location 5: Meleng River

Location 6: Bongal pukhuri

Location 7: Kotoki pukhuri

Location 8: Rajmao Pukhuri

Location 9: Tube well, Titabor

Location 10: Tube well, Indraprastha

The study was conducted from December 2013 to February 2014. Water samples were collected for both Physico-chemical and bacteriological analysis aseptically in sterile (autoclaved) bottles by following WHO standard procedures and brought to the laboratory for analysis. The bottles with the cap were immersed in the water, after which the lid was opened, and water was allowed to enter without bubbling. The sample bottles were capped and appropriately labeled with details of the source of water, date, and collection time. The samples were assessed within 6 hours of collection for their physicochemical and bacteriological analysis using water testing kit and most probable number (MPN) test, respectively.

The physicochemical tests were conducted using WTO23 Octo Aqua Test Kit (multi-parameter water testing kit, manufactured by Himedia) and Jal-Tara Arsenic Testing Kit(by Development Alternatives). The tests included pH, Hardness, Turbidity, Chloride, Nitrate, Calcium Carbonate, Residual chloride test, Fluoride test, and Arsenic test. The Arsenic testing procedure requires about 15 minutes and employs a test strip. Inorganic As⁺³ and As⁺⁵ are converted to arsine gas. This reacts with the test strip in a closed container and produces yellow to brown colors on the strip. The strip colors are compared to the color chart to determine the arsenic concentration in ppb. Broad testing range of the kit are 0, 5, 10, 25, 50, 100, 250, 500 ppb or μg/l.

For bacteriological examination of water samples, three tests were performed, namely

1. Total count by pour plate method.

2. Test for coliform and

3. Confirmed test for E.coli.

1. Total count by pour plate method

The pour plate method is usually used for counting the number of colony-forming bacteria present in a liquid specimen. In this method, a fixed amount of inoculums is placed in the center of sterile Petri-dish using a sterile pipette. Molten sterile cooled agar is then poured into the Petri-dish containing the inoculums and mixed well. At least 10-12 ml liquefied medium maintained at 44-46°C is poured into sterilized Petri-dish, and the plates are left on a level surface until adequately solidified. After solidifying, the plates are inverted and placed in the incubator. The inoculated plates are incubated at 37°C for 48 hours. Then the colonies were counted after 48 hours in a colony-counter for the presence of bacteria.

2. Test for coliform

Nutrient Agar (NA) and Brilliant green bile salt media were used to determine the total viable count and coliforms' detection, respectively. Water to be tested was diluted serially and inoculated in lactose broth. Fermentation tubes, five test tubes with double strength lactose broth medium, and 10 test tubes with single strength lactose broth medium were arranged in rows of 5 each in the test tube rack. Inoculated 10 ml of water sample in each of double strength tubes, 1mlof sample in each of 5 other single strength tubes, and the rest 5 were inoculated with 0.1 ml of the medium. Special care should be taken while inoculating the sample so that no outside contamination may occur in the inoculated tubes. It was done inside a laminar airflow instrument in an aseptic condition. The test tubes were incubated at 37°C in an incubator. After 24 hours, each tube was checked gently and examined for gas production in the small inverted Durham’s tube kept inside the bigger tubes. Only those tubes were used with gas production. If coliforms are present, then it uses the lactose present in the medium to produce acid and gas. The number of total coliforms is determined by counting the number of tubes giving positive reactions with standard statistical tables (McCardy).

3. Confirmed test for E. coli

The fermentation tubes showing gas production were gently shaken.0.1 ml of the culture with a sterile pipette were transferred to the fermentation tubes containing brilliant green lactose bile broth. The same procedure was repeated for all the positive presumptive tubes. The inoculated brilliant green lactose bile broth tubes inoculated for 48±3 hours at 37±5°C. Formation of gas in any amount in an inverted vial of brilliant green lactose bile broth formation tubes at any time within 48 hours constitutes a positive confirmed phase.

The most probable number (MPN)-multiple tube technique was used for coliform enumeration. MPN is mainly used for quality testing of water. Fecal coliforms act as an indicator of fecal contamination of water. Calculating the positive MPN values from the number of Brilliant green lactose bile broth tubes was taken from the MC CARDY table.

3. Results

The results of the water sample's physicochemical analysis are represented in Table 1. Analysis revealed that the water quality parameters were within the normal permissible limits except a few parameters. It was observed that during the study period, the pH of all the collected water samples ranged between 7-8 for all the sites. The pH of water is a crucial factor as any changes in the pH may affect the toxicity of microbial poisons in water ⁴. Water samples from locations 3, 7, and 10 were found to be hard (300mg/L). Turbidity was detected in water samples collected from locations 3, 7, 8, and 10. Nitrate (45.0mg/L) was detected in the water sample collected from location 7. Residual chlorine was not present in any of the water samples. Arsenic was detected in the water sample collected from location 9, from a tube well source. Chloride, fluoride, and iron were within the permissible limits per WHO standards for drinking water quality. The results of bacteriological analysis of water samples are represented in Table 2. The bacteriological analysis reveals that all the collected water samples were not fit for human consumption. They contain fecal coliforms and E.coli in large amounts, especially in the water samples from locations 1, 4, and 5 contaminated with fecal coliforms and E.coli.

4. Discussion

In the present study, the pH of the samples detected near neutrality which indicated that the pH has met the drinking water standards ¹¹ and poses no health risk to consumers who use the water for drinking, cooking, washing, bathing, etc. Acidic pH of water is an indication of contamination of water ⁴. The clarity of any water body determines its condition and productivity. Suspended and colloidal matter such as clay, silt, finely divided organic and inorganic matter, plankton, and other microscopic organisms are responsible for turbidity of water bodies ⁷. In the present study, the turbidity of water four water samples exceeded the permissible limit, which indicates they are unfit for consumption. Turbidity more the 1 nephelometric turbidity unit (NTU) influences disinfection efficiency ¹¹. The experimental value for the hardness of three water samples out of ten was found to exceed the WHO permissible limit, which is 300m/L, indicating they are unfit for human consumption. The significant sources of hardness are dissolved calcium and magnesium ions ^{2, 12.} The WHO standard for nitrate is 45mg/L, and the experimental value for one water sample was 45 mg/L, which is just at the border for permissible limit. This shows some exposure of the water body to inorganic constituents.

Toxicity of nitrates in infants may cause methemoglobinemia ². In the present study, the concentration of heavy metal arsenic was detected beyond the WHO permissible limit, which is 10ppb.The incidence of arsenic in drinking water has emerged as a severe health threat in several parts of the world. Adverse effects of arsenic depend on the dose and its duration of exposure. It causes melanosis, keratosis, and prolonged exposure during prenatal and early childhood, which may increase the risk of lung cancer and reproductive, neurological, cardiovascular, and hematological effects in humans ¹³.

Moreover, E.coli contamination in most of the water samples reveals fecal pollution of water. This high microbial load renders the water of the sources unfit for drinking and other domestic purposes. The prolonged consumption and use of such contaminated water may pose serious health risks to the study areas' local community. Thus, urgent and regular monitoring is necessary.

5. Conclusion

Water pollution has become a major issue of concern as it causes several water-borne diseases, thus posing health hazards to humans. The present investigation revealed that the above-studied water samples were acceptable from a majority of physicochemical parameters. In contrast, as per the biological standards, the water needs to be treated before using it for domestic purposes as E.coli were found in most water samples. Most of the water samples' coliform concentrations were higher than the maximum standard permissible limit suggested by WHO. There is an urgent need to control water pollution by controlling human activities to prevent sewage from entering the water bodies, which is the key to avoid bacterial contamination of water, thus protecting the water body and providing safe drinking water. It is imperative to educate the general public on proper waste disposal and its treatment. Also, regular monitoring of water is vital to prevent further pollution.

Acknowledgments

The authors are grateful to Dr. D. Ramaiah, Director, CSIR-NEIST Jorhat, to allow to conduct the study and provide the essential laboratory facilities to carry out the experiments and also to Mrs Palashi Bordoloi, Technical Officer for being a constant source of well-needed guidance throughout all the experiments.

Conflict of Interest

The authors declare no conflict of interest.

References