Vernier Software and Technology
Vernier Software & Technology

Water Quality

Figure from experiment 4 from Investigating Environmental Science through Inquiry


In the early 1970s, the National Sanitation Foundation, in cooperation with over 100 water quality experts, devised a standard index for measuring water quality. This index, known as the Water Quality Index, or WQI, consists of nine tests to determine water quality. These nine tests are: temperature, pH, turbidity, total solids, dissolved oxygen, biochemical oxygen demand, phosphates, nitrate, and fecal coliform. A table (or graph) for each of the nine tests indicates the water quality value (or Q-value) corresponding to the data obtained. Once the Q-value for a test has been determined, it is multiplied by a weighting factor. Each of the tests is weighted based on its relative importance to overall water quality. The resulting values for all nine tests are totaled and used to gauge the health of the water source (excellent, good, medium or average, fair, or poor).

In this experiment, you will be performing five core WQI tests: temperature change, dissolved oxygen, pH, total dissolved solids, and turbidity. A modified version of NSF WQI Worksheet for these five tests will allow you to determine the general quality of the water source being sampled.


In the Preliminary Activity, you will gain experience using a Dissolved Oxygen Probe while Determining the concentration of dissolved oxygen (DO) in a water sample provided by your teacher and then using that DO to determine the percent saturation of DO. You will also gain experience using a Temperature Probe, a Conductivity Probe, a Turbidity Sensor, and a pH Sensor.

After completing the Preliminary Activity, you will first use reference sources to find out more about water quality issues before you choose and investigate a researchable question dealing with water quality.

Sensors and Equipment

This investigation features the following Vernier sensors and equipment.

Additional Requirements

You may also need an interface and software for data collection. What do I need for data collection?

Standards Correlations

See all standards correlations for Investigating Environmental Science through Inquiry »

Investigating Environmental Science through Inquiry

See other experiments from the lab book.

1Seasons and Angle of Insolation
2A Local Weather Study
3Investigating Dissolved Oxygen
4Water Quality
5Long Term Water Monitoring
6Water Treatment
7Investigating Salinity
8Soil Temperature
9Soil Salinity
10Soil pH
11Soil Moisture
12Soil and Acid Rain
13Managing Garden Soil Moisture
14Cell Respiration (CO2)
15Biodiversity in Ecosystems
16Biochemical Oxygen Demand
17Water Cycle Column Investigations
18Decomposition Column Investigations
19Ecocolumn Investigations
20Global Warming
21UV Investigations
22Comparing Sunscreens
23Primary Productivity
24Modeling Population Growth
25Insulation Study
26Fossil Fuels
27Energy Conversion
28Wind Power
29Photovoltaic Cells
30Investigation of Passive Solar Heating
31The Effect of Acid Deposition on Aquatic Ecosystems
32Measuring Particulates
33Investigating Indoor Carbon Dioxide Concentrations
34A Pollution Study

Investigation 4 from Investigating Environmental Science through Inquiry Lab Book

<em>Investigating Environmental Science through Inquiry</em> book cover

Included in the Lab Book

Vernier lab books include word-processing files of the student instructions, essential teacher information, suggested answers, sample data and graphs, and more.

Buy the Book

Dev Reference: VST0405

Go to top