## 2 Research Methodology
### Sampling Techniques and Equipment  
Research methodology is a systematic framework used to solve research problems by employing the best and most feasible methods to conduct research while aligning with the aims and objectives of your study. The research methodology involves addressing the 'what', 'why', and 'how' of your research [27]. Table 2 explains and tabulates the S.I. units of the parameters considered in this study. The table also highlights the standard values for these parameters, as provided by the Bureau of Indian Standards and the World Health Organization. These values have served as benchmarks for years in the analysis of water quality. Additionally, this table provides information on the weighting of these parameters in the calculations of the water quality index. Each parameter has been assigned an importance based on its impact on health and the environment. These weightages are standard values and have been utilized worldwide to present a unified picture of water quality. Proper sampling procedures were followed at the 12 field stations during water sample collection. The date and time of sampling were recorded, and the sample quantity was observed. Temperature and humidity were measured, and the latitude and longitude of each station were recorded for map preparation. All the samples were collected in clean plastic containers, placed on deep ice in a dark box to maintain temperature, and transported to the laboratory for testing. Some samples arrived late at the laboratory, and, due to closing time, they were stored in a deep freezer box in the refrigerator. To prevent any sample deterioration, water samples were tested in the laboratory within 24 h of collection from the field to the lab. To assess the quality of water samples, 16 water quality parameters were analyzed. These included the following 14 physio-chemical parameters: color, odor, pH, total hardness, calcium, magnesium, total alkalinity, chlorine, iron, sulfate, turbidity, fluoride, nitrate, and TDS values. There were also 2 microbiological parameters: coliform and Escherichia coli. The IS test method was used for testing these parameters. Table 3 shows list of equipments which were used to analyze the different water quality parameters. pH was analyzed using a pH Meter, TDS was determined using a conductivity-TDS-Temperature Meter, and turbidity was monitored with a Nephelo/Turbidity Meter. Iron, fluoride, sulfate, and nitrate were tested using a Spectrophotometer. An Electronic Balance was used for weighing all the parameters, and a Hot Air Oven anduffle Furnace were employed for drying. Water samples and chemicals were stored in a refrigerator and deep freezer. Temperature and humidity were monitored using a Thermos-Hygrometer. \begin{table}
\begin{tabular}{c c} \hline \hline
**Sample No.** & **Location** \\ \hline A1 & Padam Singh Road, Karol Bagh \\ \hline A2 & Hotel Southern, Karol Bagh \\ \hline A3 & Street 49, Reghar Pura, Karol Bagh \\ \hline A4 & Street 58, Reghar Pura, Karol Bagh \\ \hline A5 & Tehkhand Village, Near Okhla Phase 1 \\ \hline A6 & Indra Kalyan Vihar (Near Dustbin), Okhla Phase 1 \\ \hline A7 & Okhla Community Development Project, Basti Vikas Kendra \\ \hline A8 & JJ Clustor, Sanjay Colony, Okhla Phase II \\ \hline A9 & Nangloi Treatment Plant \\ \hline A10 & Nangloi Treatment Plant \\ \hline A11 & Near Nangloi Treatment Plant \\ \hline A12 & Near Nangloi Treatment Plant \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Sample name and their location. _E. coli_ and total coliform were assessed through a Laminar Air Flow and Biosafety Cabinet. Color, odor, total hardness, chlorine, calcium, magnesium, and alkalinity were tested through chemical processes using the Titration Method. The range and accuracy of the equipment were always closely observed during testing. The data in Tables 4-6 suggest significant differences in various physiochemical properties, indicating that water quality varies from one location to another.