When Irrigation Association conducts water quality inspection, it mainly depends on pH value, DO (Dissolved Oxygen), EC conductivity, and temperature value, while in Huanggang Park of Yongxin Village, they also installed heavy metal detector.

(1) pH value

        pH value is a logarithmic scale used to specify the acidity or basicity of an aqueous solution; that is, the measure of the degree of acid-base. In general, when pH is less than 7, the solutions are acidic, and solutions with a pH greater than 7 are basic; when pH value equals 7, the solution is neutral. Usually in the science class experiment, litmus paper is used to detect pH value; but for Irrigation Association, professional instruments are required to detect pH value; water quality with pH value between 6~9 is suitable for irrigating farmland.

(2) DO (Dissolved Oxygen)

        It refers to the oxygen dissolved in the water, generally referred to as DO, which is expressed in units of concentration mg/L. Oxygen is the basic elements required for the biological survival (metabolism), so for the Irrigation Association, the amount of dissolved oxygen is regarded as the main indicators of water quality for good or bad; in general, the higher the concentration, the better the water quality. The best concentration range for irrigation is around 3 mg/L.

(3) EC Conductivity

         Conductivity is a physical quantity that describes the conductivity of electrolytes. Measuring the conductivity of electrolytes is a routine method for determining the content of solution ions in environmental monitoring, which is fast and reliable. Usually, when water is measured by the Irrigation Association, conductivity will be measured too, and conductivity is also one of the standards for measuring water quality. EC conductivity of water for irrigation must lower than 750 μS/cm25℃.

(4)Temperature

        From farmland irrigation to the growth of plants and animals in the water, the temperature needs to be moderate, and if the temperature is too low or too high, the irrigation association will have to understand. And the best temperature for irrigation should lower than 35 ℃.

(5) Heavy metal detector

         In Huanggang Park of Yongxin Village, heavy metal detector is installed, a powerful tool known as "time capsule ion exchange resin", developed by the team at the Department of Biological Environment System at National Taiwan University, to test heavy metal pollution in the river. With such a device, not only the cost is low, and it just takes 3 minutes to come up with results. According to leader Lin, although the Irrigation Association will be responsible mostly for the waterway with fewer responsibility for heavy metal pollution, but this device can provide regular information for water quality.。