Quality Assessment of Drinking Water from Different Water Supply in Tiruvannamalai District, Tamil Nadu, India

Health and fundamental human rights depend on having access to clean drinking water. For all routine household needs, such as drinking, cooking, and personal hygiene, safe drinking water is necessary. Approximately 780 million people lack access to safe and clean water, which leads to 6–8 million deaths annually from water-related illnesses¹.Water quality and suitability for use is affected by contaminants. The categories of contaminants of water are physical, chemical, microbiological, radiological pollutants. Water's clarity, colour, and appearance can be impacted by physical pollutants, which are solid particles suspended in the water. These pollutants are the result of human activity like building and land development as well as natural occurrences like erosion and storms. Serious health issues like cancer risk, hormone imbalance, altered brain function, immunological and reproductive system damage, cardiovascular and kidney issues, and more can be brought on by chemical pollutants like pesticides, fertilizers, and heavy metals. Water sources that have come into contact with human or animal waste can include biological pollutants such  as bacteria, viruses, algae, fungus, and parasites³. These pollutants can lead to respiratory disorders, skin infections, and gastrointestinal disorders, among other health issues. Nuclear accidents, mining, and other sources can introduce radioactive pollutants, including radioactive elements and isotopes, into water supplies. These pollutants have the potential to cause birth abnormalities and cancer. Since Tiruvannamalai is a pilgrimage site and the area is currently a major tourist destination, it is crucial to assess the town's drinking water quality to ensure that both locals and visitors can drink safely. The purpose of the current study was to assess Tiruvannamalai's drinking water quality, including that of the tap and bottle water. The chosen water sample, which was taken from various residential and commercial sections of the town, underwent a thorough physical and chemical study. This study includes analysis of different parameter such as pH, temperature, dissolved oxygen, Nitrates, total dissolved solids. The results of each parameter of the selected sample were compared to the guidelines and standards.

MATERIALS AND METHODS

Every sample of drinking water was drawn from the tap water in a residential area. Additionally, samples of reverse osmosis (RO) water also collected from residential area and bottled mineral water (MW) were gathered from nearby supermarkets. The water samples are collected in plastic bottle, which are washed with water before use. The sample  bottles are closed and located  in a dark place at a steady temperature to keep away from any       contamination and the effects of light and temperature. The following methods are used for the analysis of water sample.

Table 1: Parameters and Methods

RESULT AND DISCUSSION:

PHYSICAL PARAMETER ANALYSIS

Temperature

Physical aspects such as density, viscosity, conductivity, boiling and melting point of drinking water can be influenced by temperature. The chemistry of drinking water can be influenced by temperature. Microorganism has an impact on the impact of temperature. Some organisms thrive at low temperatures in the source water, while others thrive at higher temperatures in the distribution system or within plumbing systems. The temperature of water samples measured by submerging thermometer into the beaker for two minutes. The thermometer was placed at least 4 inches beneath the surface of water but not touched at the bottom of the beaker.

CHEMICAL PARAMETER ANALYSIS 

1. pH

pH is classed as one of the most important water quality parameters. Measurement of pH relates to the acidity or alkalinity of the water. A sample is considered to be acidic if the pH is below 7.0. Meanwhile, it is alkaline if the pH is higher than 7.0. Acidic water can lead to corrosion of metal pipes and plumping system. Meanwhile, alkaline water shows disinfection in water. The normal drinking water pH range mentioned in WHO guidelines is between 6.5 - 8.5.The pH of each water sample was measured by pH meter.

2. Dissolved oxygen

The dissolved oxygen in water is the total amount of oxygen that has already been dissolved in a water sample. Healthy drinking water should consist of dissolved oxygen levels that range from 6.5-8.0 mg/L. While high DO levels will make drinking water taste better, If DO levels drop below 6.5 mg/L, it’s likely that the water is contaminated and may be unsafe to drink. Dissolved oxygen is determined by Winkler method

WINKLER METHOD

300ml of each water sample was added with 2ml of manganese sulphate and 2ml of alkali-iodide azide in a sample bottle and closed to avoid external air becoming trapped. The sample bottle was inverted, if any bubble seen discard it, repeat the above procedure.  2ml of conc H₂SO₄ was added just above the water surface then stoppered back and inverted it to allow the sulphuric acid to dissolve the precipitate.

25ml of this solution  transferred in to conical flask and  titrated against sodium thio sulphate until pale yellow colour is produced, then starch  indicators was added and continue the titration until blue colour disappears. The dissolved oxygen is calculated by the following formula

D.O (mg/l) = Normality of Na₂S₂0₃ X Vol of Na₂S₂0₃ X eq wt factor

Volume of sample

Total Dissolved Solids

TDS stands for Total Dissolved Solids is a water quality indicator that measures the total amount of solids dissolved in water. These solids can be minerals, salts, organics, etc., and are present in the water in the form of molecules, ions, or tiny particles. TDS is usually expressed in milligrams per litre (mg/L) the higher the TDS value, the more dissolved material is in the water. Water with a high TDS value may affect the taste, odour, and overall quality of the water.  Elevated levels of dissolved solids, especially salts like sodium, can lead to hypertension, cardiovascular issues, and kidney problems when consumed regularly over time. In young children, consuming water with high dissolved solids can hinder mineral absorption critical for growth and development. TDS was estimated by Gravimetric method.

Gravimetric Method

Filter the water samples through Whatmann filter paper. Collect the filtrate in a separate flask. Take the weight of empty evaporating dish make sure the container should be dried. Add the filtrate to the container and allow the sample to stay in the oven at 103? C for 24hrs. If possible, increase the temperature of the drying oven to180? C and allow the sample to dry for up to 8hrs.Remove the container and place it in desiccator to cool in a dry air environment for at least 3-4hrs. After the container cools, reweigh the container for at least 3 times and subtract with the initial weight of the empty container.

TDS =    B-A X 1000 (mg/g) X 1000 (ml/L)

C

B = Weight of residue + container

A = Weight of empty container

C = Volume of sample (ml)

Nitrates

Sometimes high amounts of nitrate get into drinking water. Typical sources of nitrate include, fertilisers, animal wastes, particularly in areas of intensified farming, improper sewage disposal systems, industrial and food processing waste. High levels of nitrate can pose a risk to babies less than six months who are formula fed and the unborn foetus of pregnant women. Adults with specific rare metabolic disorders may also be at risk.

Nitrate Estimation

0.5, 1, 2, 3, 4, 5ml of standard potassium nitrate solution are taken in 5 separate beaker and evaporated to dryness on a hot plate. To each of them 2ml of phenol disulphonic acid is added and residue dissolved. 10ml of conc ammonia is added and diluted to 100ml standard volumetric flask. Contents were mixed well and solution from each of standard flasks is transferred to a cuvette. The absorbance is measured at 410nm wavelength using colorimeter.

25ml of water sample from three water samples is taken in beaker and evaporated to dryness on hot plate. 2ml of phenol disulphonic acid is added into each beaker and residue is dissolved.10ml of conc ammonia is added each beaker and diluted to100ml in standard flask. Contents were mixed well and the solution from the each standard flask is transferred to cuvette separately. The absorbance is measured at 410nm wavelength using colorimeter. The blank solution is prepared by excluding the water sample.

Calibration curve is drawn by plotting absorbance against conc of nitrate⁷. Using calibration curve the conc of nitrate in water samples was determined.

Biological Evaluation

Bacterial contamination includes surface runoff containing animal waste from feedlots, dog runs or other location where animal waste deposited. Human waste can also be bacterial contamination source. If disease causing bacteria are present, the most common symptoms such as fever, abdominal cramps and diarrhoea. Coliform bacteria are rod shaped gram negative non spore forming and motile or nonmotile bacteria that can ferment lactose with production of acid and gas when incubated at 35?-37?C.Presence of coliform bacteria was tested by Presumptive test.

Presumptive test

Lactose broth was prepared and distributed into the test tubes containing Durham tubes, in 10ml amount for testing samples of 1ml or less. Autoclave at 121?C for 15mins. After autoclave, Inoculate the 0.1ml of water sample to each 3 tubes, 1ml of water sample to 3 tubes and 10ml of water sample to 3 tubes. Incubate the tubes at 37?C and examine the gas formation in Durham’s tubes at 24 hours.  The test tubes are compared for positive result.

Table 2: Physio chemical parameter evaluation report summary