Japan’s Circular Economy Vision Under the Action Plan | Chapter 8Initiatives to Protect and Restore Water, Soil, Marine, and Air Environments

The covered fields include maintaining and restoring a sound water cycle, conserving water environments, conserving soil environments, conserving marine environments, conserving air environments, cross-media measures, creating favorable environments, and foundational initiatives. Measures combine regulations such as environmental standards and wastewater controls; continuous monitoring and research; development of wastewater treatment facilities and other infrastructure; cooperation with local governments, businesses, and residents; and collaboration with the Asian region.

In the water-cycle field, Japan implemented the Water Cycle Advisor System, revised the Guidelines for Using Groundwater during Disasters, and provided public-private information dissemination in FY2025, based on the Water Cycle Basic Act revised in June 2021 and the Water Cycle Basic Plan approved by the Cabinet in August 2024.

For water-quality assessment, the attainment rate for public-water-area environmental standards for health-related items was 99.1% in FY2024, while the rate for BOD or COD was 88.6%. The rates were 93.9% for rivers, 50.8% for lakes, and 78.2% for coastal waters, with lake attainment continuing to be low.

In the air-environment field, the PM2.5 environmental-standard attainment rates in FY2024 were 99.5% at general monitoring stations and 100% at roadside monitoring stations, whereas the attainment rate for photochemical oxidants was 0% at both types of stations, showing differing progress depending on the type of issue.

For residents, these measures affect the safety and comfort of familiar surroundings, including tap water, rivers, groundwater, coasts, air, and noise. Establishing water-quality standards for PFOS and PFOA, updating PFAS information, continuing radioactive-substance monitoring, and preventing asbestos dispersal support everyday decision-making by helping people understand health risks and access information.

Local governments are expected to undertake diverse practical tasks, including preparing watershed water-cycle plans, selecting and updating wastewater treatment facilities, monitoring groundwater contamination and land subsidence, collecting marine litter, and addressing noise and offensive odors. National advice, subsidies, guidelines, and joint study groups support implementation tailored to local conditions.

Businesses are expected to manage emissions of wastewater, soot and smoke, VOCs, and mercury; track information on PFAS and related substances; prevent marine plastic generation; disclose environmental information; and introduce environmentally considerate technologies. Tourism, local industries, and business partnerships that use waterfronts and satoumi can create opportunities to connect environmental conservation with regional economies and greater local appeal.

For policy management, it is necessary to address not only regulations for each environmental medium but also the circulation of nitrogen and phosphorus, climate change, ocean acidification, biodiversity, and disaster response across sectors. Japan established an action plan for sustainable nitrogen management in September 2024 and is building a continuous management system that includes international cooperation, digital technologies, and analytical quality control.

In watersheds, Japan dispatched advisors to local governments and other organizations, held study sessions, and provided technical advice on preparing and implementing plans. It also promoted the reuse of treated sewage, rainwater storage, infiltration, and reuse; Kawamachi Development, which integrates river and urban spaces; water-quality surveys by civic groups and others; and nationwide aquatic-organism surveys. The Good Practice School in November 2025 and the CDP Water and Ministry of the Environment co-hosted seminar in February 2026 promoted private-sector water-cycle activities and information disclosure.

Environmental standards cover 27 health-related items for public water areas and 28 items for groundwater, while 15 items were added as items requiring further investigation, bringing the total to 222 items. The classification designations and provisional targets for Lake Sagami, Lake Tsukui, and Lake Yachiyo were reviewed in October 2025, and consideration began on flexible operation of living-environment standards.

For wastewater treatment, Japan is developing septic tanks, sewerage systems, and agricultural community wastewater treatment facilities with completion in FY2026 in view. A July 2025 survey found that approximately 100 municipalities indicated an intention to shift from collective to individual treatment, and a study group on optimization and wider-area cooperation was established in March 2026. In FY2024, septic-tank development was promoted in approximately 1,300 of approximately 1,700 municipalities.

In enclosed coastal seas, total reductions of COD, nitrogen, and phosphorus were implemented for Tokyo Bay, Ise Bay, and the Seto Inland Sea, while a nutrient-management system was operated in the Seto Inland Sea. As of November 1, 2025, landfill licenses and approvals in the Seto Inland Sea totaled 5,027 cases and 13,782.7 ha; satoumi development supported a cumulative 41 organizations during FY2022–FY2024 and 8 regions from 2025.

For soil-contamination control, 1,680 surveys were conducted in FY2024; the cumulative totals reached 1,093 areas requiring measures and 6,506 areas requiring notification when altering land characteristics. In agricultural land, areas with cumulative detections at or above standards totaled 7,572 ha, while completed countermeasure projects covered 7,137 ha, equivalent to 94.3% of the area.

Marine-litter measures included financial support for local governments, subsidies of up to 10 million yen per prefecture for drifting and seabed litter collected by fishers and others, surveys of actual conditions, microplastic monitoring, and the dissemination of collection and source-reduction technologies. In October 2023, the Ministry of the Environment and 14 relevant prefectures launched the Seto Inland Sea Plastic-Waste Countermeasures Network.

In the air-environment field, the number of PM2.5 precautionary notifications was 0 in FY2025, total VOC emissions were reduced by approximately 60% from FY2000, and 737 fuel stations with fuel-evaporation-gas recovery functions had been certified by the end of March 2026. Electric vehicles were promoted based on targets including 100% new passenger-car sales by 2035 and 20–30% of new commercial-vehicle sales for vehicles of 8 tonnes or less by 2030.

For monitoring and response, ambient radiation dose rates were measured at 308 locations nationwide, and 649 cases of referrals for violations of marine-environment-related laws and regulations were recorded in 2025. Marine discharge of ALPS-treated water began in August 2023. Under the policy of diluting tritium concentrations to below 1,500 becquerels per liter, seawater, fish, and seaweed were measured, and interlaboratory comparisons were conducted with the IAEA and other organizations.