Water Quality Index Calculator

This calculator determines the Water Quality Index (WQI) of underground drinking water in accordance with the following ten parameters: pH distribution (\(pH\)), Oxidizing ability of KMnO₄ (\(OA (KMnO_4)\)), Nitrate(\(NO_3^-\)), Total Hardness (\(TH\)), Total dissolved solids (\(TDS\)), Chloride (\(Cl^-\)), Sulfate (\(SO_{4}^{2-}\)), Iron (\(Fe^{2+}\)), Fluoride (\(F^-\)), Copper (\(Cu^{2+}\)).

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Parameter Data Entry Parameter Range
pH distribution (pH)
Oxidizing ability
of KMnO₄ (OA (KMnO₄))
Nitrate \((NO_3^-)\)
Total Hardness (TH)
Total dissolved
solids (TDS)
Chloride (Cl⁻)
Sulfate \((SO_{4}^{2-})\)
Iron (Fe²⁺)
Fluoride (F⁻)
Copper (Cu²⁺)

Dynamic Unweighted Avarage Water Quality Index:

WQI

Good (81-100)

Fair (51-80)

Marginal (30-50)

Poor (0-29)

WQI Interpretation
Good
(81-100)

Water quality is excellent. Water in this category meets all safety standards recommended for human consumption by organizations worldwide.
Fair
(51-80)

Water quality is fair, generally safe for human consumption but may require some treatment to address minor issues.
Marginal
(30-50)

Water quality is marginal. This type of water partially meets the needs of aquatic organisms and ecosystems, but it requires serious measures to improve water quality for human consumption.
Poor
(0-29)

Water quality is poor or unsuitable. Water in this category may support tolerant organisms, but strict measures are needed to enhance water quality for sensitive organisms and agro-ecosystems.

Water Quality Index Calculation

The water quality index is calculated based on measured values for each of the parameters listed \(pH,\) \(OA (KMnO_4),\) \(NO_3^-,\) \(TH,\) \(TSS,\) \(Cl^-,\) \(SO_{4}^{2-},\) \(Fe^{2+},\) \(F^-,\) \(Cu^{2+}.\)


The calculation consists of 4 steps

  1. Get the result when the \(i-th\) parameter is measured. Denote it by \(x_i\).
  2. Sub-Indexing. Scale each calculated value \(x_i\) to a value between 0 and 1 using the following formula:

    \(SI_i=\min\left\{1,\left|\frac{x_i-x^{(st)}_i}{x^{(up)}_i-x^{(st)}_i}\right|\right\},\)

    where \(x^{(st)}_i\) is the ideal value of the parameter. \(x^{(up)}_i\) is the standard upper bound for the \(i-th\) parameter

  3. Parameter Weighting. \(w_i\) weight for the \(i-th\) parameter is calculated by the following formula.

    \(W_i=\frac{e^{SI_i}-1}{\sum\limits_{k=1}^{n}(e^{SI_k}-1)}.\)

  4. Calculating WQI. WQI is calculated by the following formula

    5. \(WQI=100-\sum\limits_{i=1}^{n}w_i\cdot SI_i\cdot 100.\)

Contacts

Nilufar Rajabova

  • +998932037532
  • +998993139416