The results of a survey conducted by the Bureau of Waterworks, Tokyo Metropolitan Government for the 2018 Tokyo Taste-test campaign follows: "Tap water is tastier," 12,112 (40.4%); "Bottled water is tastier," 13,434 (44.8%); and ", where people were asked to taste and compare tap water and bottled water, are both are tasty," 4,450 (14.8%). In 1989, the Bureau of Waterworks, Tokyo Metropolitan Government began construction to upgrade the Kanamachi Water Purification Plant in Katsushika City into an advanced water purification facility. In 2013, all the water purification plants in the Tone River system achieved 100% advanced water purification treatment. In the Tokyo Taste-test campaign that started in the same year, nearly half of the people who participated in the campaign each year have said that tap water tasted better. ^*3

There was a time when tap water in Japan was not safe and tasty to drink due to the deteriorating quality of water sources. However, in order to secure safe and reliable water, water treatment plants in urban areas have been working for 30 years to develop advanced water purification facilities. As a result, the water quality has been improved to the point where the water coming out of taps is considered to taste just as good as bottled water. One of the advanced water purification technologies that made this possible was Kubota's Porous Bottom, an underdrain system for the activated carbon adsorption process. Kubota had been improving the quality of tap water through highly advanced water purification treatment, but there was still room for further technological improvement. This is why Kubota developed Porous Bottom. Cleansing with air and water at the same time, the device efficiently cleans away contaminants, such as activated carbon, which accumulate on the filtering media, making good-tasting tap water readily available.

Kubota Porous Bottom has been adopted by water treatment plants that use granular activated carbon treatment as a highly reliable underdrain system based on its extensive track record. The adoption rate of Kubota treatment equipment in advanced water treatment facilities in Japan is approximately 80%, an overwhelming market share. In 1999, Kubota received the President's Award in the Japan Society of Industrial Machinery Manufacturers Outstanding Environment Equipment Awards for its outstanding environmental equipment. Kubota will continue to make use of highly advanced water purification treatment systems such as Porous Bottom to pursue endless improvements in the quality of tap water. Kubota will also continue to contribute to the development of a sustainable society by supporting people's quality of life.