[INTRO]
The Water Quality Index Calculator for Drinking Water is one of our newest tools. This calculator permits you to enter your drinking water testing results and we conduct a mathematical evaluation of your results and compare them with the KnowYourH2OUSA™ Standards and the KnowYourH2O World™ Standards. The KnowYourH2O USA™ Standard was developed by reviewing the drinking water standards that have been set by the EPA, other states within the United States, and clean-up standards for areas that rely on freshwater for potable water use.
The KnowYourH2OUSA™ Standard is not the same as the EPA Drinking Water Standard, because other states have set standards for parameters that are lower than the limit set by the EPA. The KnowYourH2OWorld™ Standard was developed by looking and reviewing the drinking water standards used by the World Health Organization and other countries including Australia, Canada, the United Kingdom, Israel, Hong Kong, EPA Health Advisories, the International Bottled Water Association, and a number of states that have specific standards in the United States of America. The calculator was based on the methodology that is used in Canada, but we provide scores for each group of contaminants. So rather than one value from 0 to 100, we provide a score by contaminant group, such as: Microbiological, General Quality, Metals, Disinfection By-Products, Organics, and Radiological Contaminants.
[FULL PAGE]
The Water Quality Index Calculator for Drinking Water is one of our newest tools. This calculator permits you to enter your drinking water testing results and we conduct a mathematical evaluation of your results and compare them with the KnowYourH2OUSA™ Standard and the KnowYourH2OWorld™ Standard. The KnowYourH2OUSA™ Standard was developed by reviewing the drinking water standards that have been set by the EPA, other states within the United States, and clean-up standards for areas that rely on freshwater for potable water use.
The KnowYourH2O USA™ Standard is not the same as the EPA Drinking Water Standard, because other states have set standards for parameters that are lower than the limit set by the EPA. The KnowYourH2O World™ Standard was developed by looking at and reviewing the drinking water standards used by the World Health Organization and other countries including Australia, Canada, the United Kingdom, Israel, Hong Kong, EPA Health Advisories, the International Bottled Water Association, and a number of states that have specific standards in the United States of America. The calculator was based on the methodology that is used in Canada, but we provide scores for each group of contaminants. So rather than one value from 0 to 100, we provide a score by contaminant group, such as: Microbiological, General Quality, Metals, Disinfection By-Products, Organics, and Radiological Contaminants.
When developing this tool, we followed the approach that was utilized by The Canadian Water Quality Index (CWQI) as a model. The Canadian Water Quality Index was developed by the Canadian Council of Ministers of the Environment (CCME) Water Quality Guidelines Task Group (Source). We used the approach that this index used, but changed it in a few key ways.
First Change: We divided the water quality parameters into 6 categories and not 1 big category. The categories are Microbiological, Radiological, Organics, General Water Quality, and Metals.
Second Change: We developed two separate benchmarks: the Drinking Water Standards are identified at the KnowYourH20TM (USA) and KnowYourH20TM (World). The KnowYourH20TM (USA) standard is based on the drinking water quality standards as provided by the EPA, a specific state in the USA, the Bottled Water Association, or a guidance value provided in Clean Up Standards for "Use Aquifers". The KnowYourH20TM (World) uses the KnowYourH20TM (USA), but then also includes the drinking water standards provided by the World Health Organization and specific countries and organizations, including: Australia, Canada, State of Israel, Hong Kong, and the International Bottled Water Association.
Third Change: The calculator can only handle one sample with multiple parameters and not multiple samples taken at different times at the same location with multiple parameters. (Something for the future)
Fourth Change: We added a number of water quality indices that are calculated using the imputed data. The indices are not used in the scoring. The indices are: the Langelier Saturation Index, the Rynar Index, the Larson-Skold Index, the Aggressivity or Aggressive Index, and the TDS/Conductivity Ratio. In the future, we will be looking to conduct cation/anion mass balance and other QC checks on the data.
Fifth Change: For the above calculations, we take the concentrations imputed for Calcium and Magnesium as mg CaCO3/L,sum the values, and then use the sum to contribute to the water quality calculation. It is possible that individuals may not have the values for Calcium and Magnesium in terms of CaCO3/L and may only have the value as mg Ca or Mg/L. If this is the case, the conversation factors are:
Ca (mg/L): Ca mg/L * ( 100.0869/ 40.078 ) = Ca as CaCO3/L
Mg (mg/L): Mg mg/L * ( 81.3139/ 24.305) = Mg as CaCO3/L
At this point, the user has to do this calculation manually.
Sixth Change: Microbiological Data calculator – If you have a water quality parameter test result that is either not detectable or zero, do not use the less-than sign or enter a 0. For the case of bacteria, we recommend entering a value of 0.1 for the value of 0 colonies per 100 ml, 0 organisms, or Absent. For all other cases, enter the reported detection limit as a whole number. So if the detection limit reported for the method is < 0.0001 mg/L, enter the value as 0.0001. In general, the values in the calculation are and should be entered in units of mg/L and we are assuming the samples are freshwater, i.e., drinking water.
F1 – (Number of Failed (exceeded the standard) Parameters divided by the number of parameters tested) * 100
F2 - (Number of Failed Tests divided by the number tests) * 100
At this time, F1 and F2 will always be equal, because we are only looking at 1 sample at a time.
A test can fail in most cases by exceeding a goal value. The equation for this condition is (Failed Test Result Value divided by the Objective Value) -1. This should always result in a positive number.
In a few cases like pH, hardness, and alkalinity, the test can fail because it falls below a goal value. If this situation occurs, the equation is: (the Objective Value divided by the Failed Test Value) - 1. This should always be a positive number. Therefore, the calculator determines which equation is appropriate.
NSE - This is the sum of all the Exclusion values both below and above the standard divided by the number of tests.
F3 - (NSE / (0.01NSE +0.01)) This factor is an amplitude; it “represents the amount by which failed test values do not meet their guidelines”.
WQI (Water Quality Index) - (100 – SQRT((F1^2+F^2+F3^2)/1.732))
Once the factors have been obtained, the index itself can be calculated by summing the three factors as if they were vectors and using the Pythagorean theorem. The sum of the squares of each factor is therefore equal to the square of the KnowYourH20 WQI. This approach treats the index as a three-dimensional space defined by each factor along one axis. With this model, the index changes in direct proportion to changes in all three factors. The divisor, 1.732, normalizes the resultant values to a range between 0 and 100, where 0 represents the “worst” water quality and 100 represents the “best” water quality.
Excellent: (KnowYourH20 WQI Value 90 to 100) – The water quality is characterized by a virtual absence of any threat or impairment; the water quality is very close to ideal. We use the Letter, ‘A,’ to represent this condition.
Good: (KnowYourH20 WQI Value 80 to 89) – The water quality is protected with only a minor degree of threat or impairment; conditions rarely depart from ‘natural’ or desirable levels. We use the Letter, ‘B,’ to represent this condition.
Fair: (KnowYourH20 WQI Value 70 to 79) – The water quality is usually protected but is occasionally threatened or impaired; conditions sometimes depart from ‘natural’ or desirable levels. We use the Letter, ‘C,’ to represent this condition.
Marginal: (KnowYourH20 WQI Value 60 to 60) – The water quality is frequently threatened or impaired; conditions often depart from ‘natural’ or desirable levels. We use the Letter, ‘D,’ to represent this condition.
Poor: (KnowYourH20 WQI Value < 60 ) – The water quality is almost always threatened or impaired; conditions usually depart from ‘natural’ or desirable levels. We use the Letter, ‘D,’ to represent this condition. Water of this quality is probably not potable and would require considerable treatment to become so.
We present the results based on both the KnowYourH20™ (USA) and KnowYourH20™ (World) standards. The goal is to convert the complex data into a set of water quality indices, one index for each water quality category: Microbiological, Radiological, Organics, General Water Quality, and Metals, an approach that is quick and easy for the public to understand. At present, our goal is to map the Water Quality Index Calculations Results by zip code and country for public access without identifying specific individual locations. Users would have point access to their own data and calculations.