Japan is renowned for its clean water, with the majority of its surface and groundwaters meeting World Health Organization standards. This is due to a combination of strict regulations on industrial pollution, natural barriers like mountains which filter out pollutants before they reach larger bodies of water, and initiatives taken by both government authorities and citizens to preserve nature. Technology also plays an important role in maintaining high-quality waters in Japan through advanced wastewater treatment systems and monitoring systems that track changes in quality over time.