National Sanitation Foundation Water Quality Index method (NSFWQI) and Its Calculation Procedure

Summary

In this video, the speaker introduces the National Sanitation Foundation Water Quality Index (NSFWQI), explaining its development, purpose, and method of calculation. Water quality indexes simplify complex water data, making it understandable for the general public. The speaker walks through the process of selecting water parameters, developing rating curves, and assigning weight factors for accurate calculations. The video further demonstrates the procedure to calculate water quality using hypothetical data and interprets the results, helping viewers understand how the index can categorize water quality from poor to excellent. This method aids in easily assessing water sources.

Takeaways

• 😀 Water Quality Index (WQI) simplifies complex water analytical data into understandable information for the general public.
• 😀 The National Sanitation Foundation Water Quality Index (NSFWI) method was developed in 1971 by Brown et al. in collaboration with the NSF.
• 😀 NSFWI incorporates nine key water parameters: Dissolved Oxygen, Fecal Coliform, pH, Biological Oxygen Demand (BOD), Nitrate, Phosphate, Water Temperature, Turbidity, and Total Dissolved Solids (TDS).
• 😀 The NSFWI method uses rating curves for each parameter to convert data into sub-index values (Q values) that are easy to understand.
• 😀 The weight factors (W_i) for each parameter in NSFWI are determined based on expert ratings and signify the importance of each parameter in assessing water quality.
• 😀 The water quality is classified into five categories based on the NSFWI value: Very Poor (0-25), Poor (26-50), Moderate (51-70), Good (71-90), and Excellent (91-100).
• 😀 Experts initially selected 35 parameters, later refined to 15, and ultimately, nine parameters were included in the NSFWI calculation.
• 😀 The calculation involves determining the Q value for each parameter using rating curves, then applying the weight factors (W_i) for each parameter.
• 😀 Example calculations show how to determine the Q value from hypothetical data using rating curves and convert it into the final NSFWI index.
• 😀 The video emphasizes the usefulness of the NSFWI method in converting complex water quality data into a simple, comprehensible value for better public understanding.

Q & A

What is the purpose of a water quality index (WQI)?

The purpose of a water quality index (WQI) is to convert complex water analytical data into a simple and easily understandable value for the general public. It helps to evaluate the overall quality of water and whether it is suitable for consumption or other uses.

Who first developed the water quality index (WQI)?

The water quality index (WQI) was first developed by Horton in 1965.

What is the main objective of calculating a water quality index (WQI)?

The main objective of calculating a WQI is to summarize and represent water quality information through a single value that is easily understandable, even by non-experts.

What are the nine parameters incorporated in the NSF water quality index (NSFWI)?

The nine parameters incorporated in the NSF water quality index (NSFWI) are dissolved oxygen, fecal coliform, pH, biological oxygen demand, nitrate, phosphate, water temperature, turbidity, and total dissolved solids.

How was the NSF water quality index (NSFWI) developed?

The NSF water quality index was developed in 1971 by Brown and collaborators in partnership with the National Sanitation Foundation. A team of 142 experts was involved in selecting the water quality parameters, developing rating curves, and assigning weight factors for each parameter.

How are the parameters for the NSF water quality index selected?

The parameters for the NSF water quality index were initially selected by 142 experts. They were asked to choose water quality parameters they considered essential, resulting in 44 parameters. After further selection, 15 parameters were narrowed down, and ultimately, 9 parameters were chosen for the final index.

What is a rating curve and how is it used in the NSF water quality index?

A rating curve is a graphical representation that shows the relationship between the water quality parameter value (such as pH or dissolved oxygen) and the corresponding sub-index (Q value). The Q value for each parameter is determined using the rating curve, which helps to assess the water's quality.

How is the weight factor (Wi) assigned to each parameter in the NSF water quality index?

The weight factor for each parameter is assigned based on the expert ratings, which are averaged and then normalized. The sum of all the weight factors for the nine parameters equals 1.

What does the range of the NSF water quality index (0 to 100) represent?

The NSF water quality index ranges from 0 to 100, with different classes indicating water quality. A score from 0-25 indicates very poor water quality, 26-50 indicates poor quality, 51-70 indicates moderate quality, 71-90 indicates good quality, and 91-100 indicates excellent water quality.

What is the benefit of using the NSF water quality index (NSFWI)?

The benefit of using the NSF water quality index is that it simplifies complex water quality data, making it easy for the general public to understand and assess the quality of water. It helps in comparing different water sources and identifying whether the water is suitable for consumption or other uses.