World’s cleanest countries 2025: fresh air, pure water, and waste management

A truly clean country is not defined solely by streets free of rubbish or the scent of fresh air. It must also have sustainable foundational systems in place, including good air quality, safe drinking water, effective waste management, and universal access to adequate sanitation and hygiene. 

These elements not only help prevent the spread of disease but also enhance quality of life, support the economy, and protect the environment in the long term. 

Countries that can maintain cleanliness at a structural level tend to enjoy healthier populations, a higher quality of living, and recognition as models of sustainable development in the eyes of the global community.

Scoring based on four key factors

Ultimate Kilimanjaro developed a “Clean Score” index using 2024 data across four main dimensions: air quality, water, sanitation (including hygiene), and waste management. The methodology is as follows.

• Air quality – Data from the 2024 World Air Quality Report by IQAir, which compiles information from over 40,000 air monitoring stations across 8,954 locations in 138 countries.
• Water, sanitation and hygiene – Based on the WHO/UNICEF Joint Monitoring Programme, which tracks global access to safe water, sanitation, and hygiene facilities.
• Waste management – Indicators drawn from Yale’s 2024 Environmental Performance Index (EPI), covering controlled waste disposal and recovery rates.

Data processing

For 2024, complete data across all four dimensions was available for 150 countries. The processing steps included,

• Normalisation – Converting each country’s score in every indicator to a 0–100 scale.
• Weighting – Assigning weights of 30% for air quality, 25% each for water and waste, and 20% for sanitation/hygiene.
• Composite score calculation – The lower the composite score, the cleaner the country is considered to be.

Countries with the lowest “Clean Score” rank as the cleanest in the world.

The world’s cleanest countries 2025

 

No. 10: Singapore

• Air: 8
• Water: 5
• Waste: 7
• Hygiene: 4

Overall Clean Score: 6.2

Singapore manages its urban environment with precision. Despite its small size, it controls car ownership growth and enforces strict Euro VI emissions standards to curb air pollution.

For water security, the country relies on desalination and NEWater, a high-grade recycled water system, to cope with droughts. All municipal waste from sealed bins is processed in four waste-to-energy plants with stringent emissions controls.

High-rise buildings use pneumatic waste conveyance systems to reduce pests. A deposit return scheme for beverage containers will launch in 2025 to boost recycling rates.

Public spaces are kept immaculate, with hawker centres inspected weekly to ensure food safety and promote handwashing.

Singapore’s drains and roadside areas are kept litter-free through strict fines and public naming of offenders. This balance of firm legislation, technology, and civic discipline ensures the city’s long-term cleanliness and liveability.

No. 9: Estonia

• Air: 6
• Water: 5
• Waste: 8
• Hygiene: 4

Overall Clean Score: 5.9

Estonia combines abundant natural resources with modern governance. Surrounded by dense pine forests and situated on the Gulf of Finland, the country has shifted from Soviet-era heavy industry to cleaner energy sources, including LNG, wind power, and reduced peat use, cutting the black smoke that once hung over cities.

A plastic bag tax introduced in 2017 swiftly reduced litter, while EU funding has modernised Tallinn’s underground sewer system and marine wastewater treatment plants.

Waste-to-energy facilities incinerate refuse for heat while keeping emissions under strict control. Communities nationwide hold monthly “clean-up days,” with schools, companies, and citizens taking part.

A GPS tracking system for waste trucks prevents illegal dumping in forests, making such offences rare. This combination of environmental regulation, technology, and public engagement has made Estonia one of the cleanest and most sustainable nations in modern Europe.

 

No. 8: Australia

• Air: 7
• Water: 5
• Waste: 7
• Hygiene: 3

Overall Clean Score: 5.7

Australia’s clean air and strong public infrastructure are helped by the fact that most of its population lives along well-ventilated coastlines.

Vehicle restrictions reduce PM2.5 dust levels, and one in three homes has rooftop solar panels, cutting reliance on gas. Advanced water facilities supply safe drinking water even to arid areas such as Alice Springs, showcasing robust infrastructure.

Waste management is equally impressive: a container return scheme has pushed recycling rates above 80%. Landfills are strictly regulated and equipped with methane capture for power generation.

Food waste collected in green bins is processed into biogas for buses. Major cities have road designs that prevent wastewater from flowing into the sea, keeping beaches pristine and protecting marine ecosystems for sustainable tourism.

 

No. 7: Sweden

• Air: 7
• Water: 4
• Waste: 5
• Hygiene: 3

Overall Clean Score: 5.0

From the southern city of Malmö to the northern town of Kiruna, Sweden relies primarily on hydropower for its electricity, ensuring clean air and low greenhouse gas emissions. Strict vehicle regulations, including mandatory exhaust filters and the promotion of biofuels, have successfully reduced urban smog.

Tap water sourced from natural glacial streams is of such high quality that it requires no chlorine treatment, delivering a fresh, clean taste that is safe to drink.

Sweden sends barely 1% of its waste to landfill, with the rest recycled or used in waste-to-energy plants that supply district heating. A landfill tax funds recycling centres, which are available free of charge even in small villages.

Schools play an active role in environmental awareness, with compost plots to teach food waste management and student monitoring of school-generated waste. In winter, public campaigns encourage handwashing on trams and other enclosed public transport to prevent the spread of illness, an example of Sweden’s integration of public health and sanitation culture.

 

Joint 4th: Norway

• Air: 6
• Water: 4
• Waste: 6
• Hygiene: 3

Overall Clean Score: 4.9

Norway scores an impressive 90.9 in the Environmental Performance Index’s air pollution category, reflecting exceptionally clean air and low pollution levels. Its sanitation and drinking water systems are also outstanding, earning a score of 97.6, indicative of excellent public health standards.

Bergen has pioneered underground pneumatic waste collection systems that transport rubbish from homes to central collection points without the need for collection trucks, reducing air pollution and boosting recycling rates by 15%.

Almost 100% of Norway’s electricity comes from renewable hydropower, a clean, zero-emissions energy source. The country also enforces strict environmental regulations, from controlling industrial emissions to promoting widespread adoption of electric vehicles.

 

Joint 4th: Denmark

• Air: 6
• Water: 4
• Waste: 6
• Hygiene: 3

Overall Clean Score: 4.9

Wind turbines along the North Sea generate more than half of Denmark’s electricity. In Copenhagen, every drop of wastewater is thoroughly treated, with sludge converted into biogas to power city buses.

Over 92% of bottles and beverage containers are returned to shops for recycling.

Separating food waste is mandatory, with organic matter sent for energy recovery. Tap water is filtered through deep sand layers, making bottled water purchases largely unnecessary.

In the city centre, cycle paths outnumber car lanes, reducing air pollution. Most waste is incinerated for energy, leaving almost nothing for landfill.

 

Joint 4th: Finland

• Air: 6
• Water: 4
• Waste: 6
• Hygiene: 3

Overall Clean Score: 4.9

Boreal forests cover three-quarters of Finland, effectively filtering fine particulate matter from the air. Combined heat and power plants run on biomass and operate with strict filtration systems.

Lake water is naturally filtered through sand, producing clean drinking water that flows directly to household taps.

Local communities accept batteries, electronic waste, and car tyres free of charge to ensure sustainable waste management. Holiday homes are required to have sealed dry toilets or be connected to full-scale wastewater treatment systems to prevent nutrient leakage into the environment.

Producer responsibility laws require companies to help collect and recycle packaging. Children learn composting from primary school and take part in monitoring litter in playgrounds, fostering a culture of cleanliness from an early age.

 

No. 3: New Zealand

• Air: 5
• Water: 4
• Waste: 6
• Hygiene: 3

Overall Clean Score: 4.6

Surrounded by the pure Pacific breeze, New Zealand benefits from winds that carry away smoke and pollutants from its shores.

The nation’s primary energy sources, hydroelectric dams and geothermal plants, keep industrial emissions to a minimum. Dairy herds graze under strict nutrient management standards to protect waterways.

To maintain the quality of rivers favoured by anglers, councils provide well-organised recycling bins for glass, paper, and food waste.

National parks strictly prohibit single-use plastics, keeping hiking trails pristine and peaceful for visitors.

Wastewater treatment systems are tightly monitored and sealed to protect rural groundwater supplies. The result is a tourism experience defined by lungs full of clean air and the ability to drink pure water straight from nature.

 

No. 2: Switzerland

Air: 5

Water: 3

Waste: 5

Hygiene: 2

Overall Clean Score: 3.9

In the Swiss Alps, freight is transported by electric trains rather than lorries, using base tunnels to reach the heart of the country.

A portion of electricity is generated from clean power sources, while pristine alpine lakes provide drinking water filtered through UV treatment. A nationwide “pay-as-you-throw” scheme encourages households to sort and recycle glass, paper, and metals.

Waste incineration plants capture exhaust gases and channel steam to nearby chocolate factories. Wastewater treatment plants add extra stages to remove antibiotics before discharge.

Mountain huts are required to bring all waste back down, helping to protect headwaters and snowy peaks. Even motorway rest areas remain spotless, reflecting the Swiss pride in environmental stewardship.

 

No. 1: Iceland

Air: 4

Water: 3

Waste: 5

Hygiene: 2

Overall Clean Score: 3.6

Situated on the Mid-Atlantic Ridge, Iceland makes exceptional use of geothermal energy, which not only heats homes but also melts snow from roads in winter.

Clean Atlantic winds help keep the air fresh, while tap water comes directly from naturally pure volcanic springs, requiring no chemical treatment.

The country has a highly efficient waste management system, with most waste converted into energy. Recycling points accept everything from fishing nets to car tyres, all processed using renewable energy.

Comprehensive sewage systems extend even into rural areas, ensuring streams remain clear and ideal for wild salmon habitats.