First of all, it should be clear that many people think that the drainage ditch may be similar to what we call sewer wastewater. However, the sewers in Japan are by no means the same as what we call sewers. The water in Japanese sewers can be used normally, while the sewage in China is domestic sewage, which is definitely not the same as that in China.
Japan, on the other hand, is narrow and sparsely populated and easy to manage. In addition, the local people generally attach great importance to environmental protection and garbage sorting, so the sanitation of Japanese drainage ditches is very good.
However, it is not spontaneous to raise koi fish in Japanese drains. In fact, Japan was also affected by water pollution at first. In order to solve this situation, the Japanese people spontaneously organized a movement to clean up rivers, and put more than 3,000 koi fish into drainage ditches, which not only urged them to pay attention to the environment, but also used these experiences to test the degree of environmental protection. After years of persistence and accumulation, the Japanese can make the drainage ditch and koi fish live in peace, which is also a much-told story between man and nature.
Japan introduced rivers outside the city into the city, which is what we now call a drainage ditch. The water in the drain is liquid, which will flow into the kitchen of every household, and the water in the kitchen will also flow into the drain. These food scraps naturally become fish feed. Japanese sewage will never be discharged into the drain. Other pipelines are dedicated to discharging sewage. In fact, the water in the drainage ditch in Japan collects surface water, which can be said to be a reservoir in Japan.
Then someone said, how did the Japanese ensure the healthy growth of koi fish? In fact, in this respect, Japan has also made relevant regulations to manage water quality problems. For example, urban greening is not allowed to spray pesticides or other medicines, and kitchens generally do not use chemical cleaning products for washing. The introduction of these measures not only ensures the cleanliness of water quality, but also facilitates the use of water by residents.