"Where does tap water come from?" "Can the water left after washing vegetables still be used?" ... In the drinking water science mini-class, a unique "Knowing the Source of Drinking Water—Urban Water Supply Safety Science Popularization Activity" is underway.

In order to help children establish the awareness of saving water and protecting the water environment from an early age, the Drinking Water Safety Guarantee Engineering Technology Innovation Center of the Ministry of Housing and Urban-Rural Development recently took the opportunity of International Children's Day to invite more than 40 kindergarten and primary school children and their parents to participate in the activity. The activity was divided into four sections: the center's mobile laboratory, the water quality analysis laboratory, the drinking water science mini-class, and the tap water process mini-experiment. Through visits, explanations, and interactive formats, it popularized knowledge related to water quality testing and drinking water safety for young people and children, cultivated their practical ability and scientific literacy, and raised their awareness of drinking water safety.

On-site visit to testing sites

During the visit, the children walked into the mobile laboratory and the water quality analysis laboratory with curiosity, observing water quality analysis equipment up close. Under the patient explanations of the staff, the children carefully learned about the working principles of these devices and their important role in safeguarding drinking water safety. They actively asked questions and showed strong interest in scientific knowledge.

Afterward, the children entered the drinking water science mini-class. Engineers from the center used lively and interesting methods to tell the children about topics such as "what is domestic drinking water," "how do we test drinking water," and "what are the differences between different types of drinking water." "I know! Water is mainly used for washing hands, washing vegetables, and cleaning!" The children raised their hands enthusiastically and seriously answered questions about the difference between drinking water and water use, and sorted out the common uses of drinking water in daily life.

In the testing segment, the engineers first introduced the full process of routine water quality testing. To let the children participate personally in the testing process, an on-site water quality testing experiment was conducted. The children used portable turbidity meters and pH meters (acid-base meters) to test tap water and filtered purified water, including key indicators such as pH and chlorine content, and compared them with reference data. The engineers patiently explained to the children the reasons for the differences in the test results, giving them a more intuitive understanding of water quality testing. In addition, the children also took part in an odor identification test. It is reported that each page of the odor identification test book used in the test had a sniffing strip with a different scent embedded in it. With the help of their parents, the children used pencils to scratch the sniffing strips to release the scent, carefully sniffed, and chose the correct odor from four candidate answers. Each correct answer earned one point, and prizes were awarded according to the final scores.

The engineer said: "Through the experiments, children are encouraged to develop the good habit of protecting water resources from an early age, starting from small things, saving water, and protecting the rivers and lakes around them."

Intuitive experience of the water treatment process

In the tap water process mini-experiment segment, the center carefully planned a water purification experiment so that the children and parents could more intuitively experience the water treatment process and feel the charm of science.

First, engineers from the center demonstrated the coagulation-sedimentation process on site. After adding flocculant to a cup of muddy water and stirring, the children were surprised to find that the water became clear after a while. The engineer explained that impurities such as solid particles in water are generally negatively charged, while the added flocculant is positively charged. This is like putting a large number of "magnets" into dirty water, attracting the impurities to gather around them into "little clumps" that gradually settle to the bottom of the cup.

Next, the engineers led the children in a filtration mini-experiment. The children picked up the materials and, following the demonstration diagram, assembled a simple homemade filter step by step, carefully placing purification stones, ceramic sand, activated carbon, and quartz sand, separating each layer with filter gauze, and connecting a receiving device at the bottom. While assembling, the children observed and thought carefully, and from time to time expressed their expectations about whether the filter could successfully purify the dirty water.

The children slowly poured the dirty water into the filter and watched closely as the water flowed through each layer of filter material. Under the preliminary filtration of the filter gauze, large particles in the water were effectively intercepted. Then, the purification stones, ceramic sand, activated carbon, and quartz sand further adsorbed and filtered tiny particles and harmful substances in the water. After the fine treatment by the experimental apparatus, the originally turbid dirty water gradually became clear and transparent. When clear water slowly flowed out from the bottom of the filter, the children observed the magical changes, shared their discoveries with their companions, and wore joyful smiles on their faces.

The children said that this science popularization activity not only helped them understand the importance of drinking water safety, but also cultivated their ability to observe, think, and practice through hands-on experience. The parents also highly praised the activity, believing that in the process of participation, the children greatly stimulated their interest, enthusiasm, and creativity by discovering problems, raising questions, discussing problems, and solving problems.

The relevant person in charge said that the center will continue to give full play to its professional advantages, plan and hold more science popularization activities in diverse forms and with rich content, and provide more young people and children with a platform to learn about drinking water safety. It is hoped that through the "little hands holding big hands" approach, every child can establish the awareness of cherishing water resources and protecting the water environment, and jointly safeguard the precious source of life.