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1. What is the workshop about?

The Computer Science department and Data & News Society have invited Shan He, a Guangzhou-based civic scientist as well as the project director of Chinese NGO Greenovation Hub, to hold a workshop on harvesting water quality data through simple chemical test kits and DIY water monitoring device for environmental investigation on the 18th of January, 2018. A dozen of mixed students from computer science and journalism background and some interested citizens attended and worked in groups.

Ms. Shan He

Shan He, a Guangzhou-based data scientist, as well as the project director of Chinese NGO Greenovation Hub and science community Public Lab, held the workshop on DIY water monitoring.

2. Inspiration behind the workshop

The workshop was inspired by the time when Shan visited the rural parts of Chinese cities such as Tianjin and Shandong, where inadequate and poor sanitation facilities there are the culprits of the water contamination.

Shen showed the appalling photos of rural villagers drawing brownish drinking water from communal standpipes, as well as water source being polluted by waste and chemicals. The government calmed the villagers that the water was drinkable despite it being turbid and yellowy. She determined to use simple devices to prove if the pollutants ever exist.

Waste Water

Villagers of Dazhangzhong village in Tianjin are forced to draw polluted drinking water from a communal pipe. Photo: Shang He


The neighbouring areas of the water source in Dazhangzhong village are stacked with waste. Photo: Shang He

3. Water-testing activities during the workshop?

Different water samples were used for the water quality testing activities, including tap water, boiled water, distilled water and domestic sewage.

3.1 Testing water quality using chemical testing kits

The water quality testing activities include measuring the following parameters:

a. pH value

Universal indicator paper can be used to test the pH value of water to show its level of acidity and basicity.


Universal indicator paper which exhibits colour changes over a pH value change, indicates the acidity and basicity of solutions.

The pH scale runs from pH 0 to pH 14. Red stands for strongly acidic while dark purple stands for strongly alkaline. Neutral pH 7 is indicated by green. Colour scale testing can also be applied to testing the levels of chlorine and nitrogen gas.

pH scale

The pH scale.

b. TDS (total dissolved solids)

TDS meter measures the concentration of total dissolved solids in water. The principle behind its measurement is the electrical conductivity (EC) of the solvent. Since water contains ionised solids such as salts and minerals, it can generate electrical conductivity.


The TDS meters.

To start the measurement, remove the cap of the electrode cells. Fill the cap by ⅔ and insert the electrodes into the cap. Then gently shake it and wait for the value of TDS in three seconds.

c. Nitrogen

Dip the test strip with two fields into the test solution for two seconds. Check the colour scale after two minutes. Hole the bottom of the strip and compare with the colour scale. The upper field and the lower field are for nitrate and nitrite comparison respectively.

Nitrate and nitrate scale.png

The colour scale of nitrate (top) and nitrite (below) in water. According to the Standards for Drinking Water Quality gb5749-2006, the level of nitrate and nitrite in water should be 10 milligrams and one milligram respectively.

3.2 Building a water quality testing device using Arduino and water sensors

To determine more accurate data, Arduino Create is used to analyse the data of water quality with a couple of chips, wires and sensors.

Arduino 1

Arduino Create can configure data imported from the connected sensor.

Arduino Create is a digital platform that allows code writing and data configuration. Arduino can be connected to sensors and import data into the central repository board. It also allows sketches to be uploaded from the web browser. In addition, users can import sketches using zip files share the sketches with other Arduino users.

Arduino 2

Arduino Create can configure data imported from the connected sensor.


Different parts of the IO expansion board are connected with wires and a sensor dipped in water sample. The board helps facilitate the import of data on water quality to the computer.


Activate the connection of the IO board to the Arduino site.

Arduino 4.jpg

Configuration of water quality data on Arduino site.

Arduino Create is not as difficult as it appears to be. Some students without computer science and programming background were able to follow suit.

Author/ Erin Chan

Editor/ Celia Lai