Cities

Improve urban waste management and transition to zero-waste cities

In 2023, more than half of the world’s population lived in cities, and urbanization is accelerating especially in developing countries. Coupled with growing income levels and increased consumerism, global waste generation rates are expected to grow at twice the rate of population growth between now and 2050. If these trends continue, global solid-waste-related emissions will increase from 1.6 billion tonnes of carbon dioxide equivalent (CO2e) in 2023 to 2.6. billion tons of CO2e by 2050 unless effective zero-waste policies and programs are implemented.

Domestic waste is high in organic matter from food and animal waste, as well as sludge, sullage, textiles and paper — all of which emit methane, a gas with 26 times the potency of CO2. Non-biodegradable wastes (notably in the form of construction wastes, plastics, metal, aluminum canes, tires, most chemicals and polystyrene fibers) do not degrade over time unless recycled or reused.

Achieving zero-waste outcomes will require shifts in the way biodegradable (organic) and non-biodegradable (inorganic) components are managed. Effective zero-waste programs promote circularity and reduction in resource usage instead of the linear-economy paradigm of “extract-produce-discard.” Transitioning to and maintaining zero-waste outcomes presents a win-win situation for cities, enabling them to contribute to climate mitigation while also offering citizens and regional ecosystems cleaner and healthier living environments.

Currently in developing countries, only some of these inorganic wastes can be reused in construction and the building of roads; the rest of them get deposited in dumpsites, burned or dumped into waterways. Simultaneously, electronic wastes (e-wastes) contain potentially toxic chemicals, and huge quantities of plastics get transported through waterways to the oceans, choking riverine and marine organisms. Harmful microplastics are now a part of the human food chain.

Achieving zero-waste outcomes can cause a myriad of benefits at the local, regional and global levels: local residents benefit from clean streets and healthy neighborhoods and waterways; regional ecosystems benefit from reduced stress and pollution; and the global economy benefits from the elimination of harmful impacts caused by uncontrolled greenhouse gas emissions, notably methane.

While the cities system is linked with the concept of circularity, the focus of circularity on organic waste is still a nascent area of study, with most research currently centered on inorganic waste (such as plastics, paper, glass, and other materials).

Data Insights

Is the world making enough progress toward the most important outcomes?

Systems Change Lab assesses progress made across 5 outcome indicators. Click a chart to explore the data.

What factors may enable or prevent change?

Systems Change Lab identifies 13 enablers and barriers that may help spur or impede change. Click a chart to explore the data.

Progress toward targets

Systems Change Lab tracks progress made across 5 outcome indicators. outcome indicator. Explore the data and learn about key actions supporting systems change.

Transition to zero waste

Proportion of solid waste segregated into organics, dry recyclables and residual wastes

Inorganic wastes — including paper, plastics, metal and aluminum wastes — have potential reuse or recycle value and are already incorporated as inputs in supply chains, to different degrees.

Zero-waste strategies can be formulated after analysis of the composition of solid waste generation, in terms of paper, plastics, glass, building materials, kitchen wastes, human and animal wastes. This composition varies across income levels and the social and cultural characteristics of cities.

In low- and middle-income countries, organic and food waste form higher proportions of solid waste generated — 56% in low-income and 53% in middle-income countries, respectively. Typically, as income levels rise, so does the share of inorganic or dry content wastes, such as plastics, paper, packaging materials, metal and glass. However, recycling and reuse of inorganic or dry content wastes in low- and middle-income countries are often undertaken by informal waste pickers, who usually represent the poorest of the urban poor.

There is currently no comprehensive data available on this indicator, but there are estimates indicating that barely 9% of solid waste (including inorganic waste) gets disposed of through sanitary landfills.

Share of daily municipal waste that is inorganic

Inorganic wastes — including paper, plastics, metal and aluminum wastes — have potential reuse or recycle value and are already incorporated as inputs in supply chains, to different degrees.

Zero-waste strategies can be formulated after analysis of the composition of solid waste generation, in terms of paper, plastics, glass, building materials, kitchen wastes, human and animal wastes. This composition varies across income levels and the social and cultural characteristics of cities.

In low- and middle-income countries, organic and food waste form higher proportions of solid waste generated — 56% in low-income and 53% in middle-income countries, respectively. Typically, as income levels rise, so does the share of inorganic or dry content wastes, such as plastics, paper, packaging materials, metal and glass. However, recycling and reuse of inorganic or dry content wastes in low- and middle-income countries are often undertaken by informal waste pickers, who usually represent the poorest of the urban poor.

There is currently no comprehensive data available on this indicator, but there are estimates indicating that barely 9% of solid waste (including inorganic waste) gets disposed of through sanitary landfills.

Proportion of generated solid waste volumes disposed in sanitary landfills

Urban waste should be safely disposed of in sanitary landfills; other forms of disposal lead to unsatisfactory health and environmental outcomes.

A successful shift toward zero-waste outcomes requires policies that encourage circularity in resource usage while minimizing residual waste disposal.

Ideally, residual wastes should be disposed of through sanitary landfills that are designed to safeguard against land and water pollution, with complementary investments in landfill gas collection systems that can capture greenhouse gasses like methane and nitrous oxide, as is common practice in most high-income countries.

However, in cities in developing countries, the predominant practice is the open dumping of waste, which leads to land and water pollution. In cities in most of the low-income countries of sub-Saharan Africa and South Asia, for instance, 93% of waste is disposed of through open dumping.

The current state of play can be described in terms of sustainable waste management by level of development. While waste collection by municipal agencies (or those designated by the municipality) in low-income countries is already grossly inadequate, poor waste management practices further endanger both the local ecosystem and the global commons. Waste disposal that takes place mainly through open dumpsites is harmful to the local ecosystem due to subsequent land and water pollution, and to the global commons through continuous methane emissions. Recycling is also considerably more limited in low-income countries compared to what is achieved in high-income countries.

Adequate waste management practices are almost exclusively seen in high- and upper-middle-income countries.

There is currently no comprehensive data available on this indicator.

Estimated volume of safely disposed wastewater

Onsite wastewater disposal is a significant source of organic waste in cities in developing countries and should be included in overall waste estimates.

Wastewater consists of water that is generated from sanitation facilities (black water) and water from kitchen sinks and bathing facilities (gray water). The total annual estimated wastewater generated globally in 2020 was 359 billion cubic meters. As populations continue to grow, both water consumption and wastewater volume will also increase.

In cities, the volume of wastewater mirrors the consumption of clean water by households and business establishments, since most water consumed by humans and animals cycles back into the ecosystem through sewers and drains (reticulated systems) or through septic tanks and pit latrines (onsite disposal systems). Fecal sludge from these onsite systems often contributes to most of the waste pollution.

For example, in Sub-Saharan Africa and many Asian countries, piped sewerage systems are absent in most cities. Fecal sludge emits significant volumes of methane on a continuous basis and is therefore a significant contributor to global warming, apart from causing significant environmental health problems locally.

Share of human waste treated in urban wastewater facilities

A low share of human waste processed through wastewater treatment plants reflects a significant problem of fecal sludge management.

As the global population grows, the volume of human waste inevitably grows as well.

In sewers and drains, this waste is “sewage;” in onsite sanitation systems, where it is primarily solid, it is “septage.” Treated wastewater contains solid residues known as sludge. The solid content of mechanically dewatered sludge typically ranges from 20%-45% solids by weight. Solid residues in onsite systems take the form of septage or fecal sludge, which needs to be emptied either manually or mechanically once the underground facility is filled.

These residues are high in methane content and are therefore a significant passive contributor to greenhouse gas emissions from cities, as methane seeps out from millions of small sources such as septic tanks, waste dumpsites, littered organic wastes, and others.

The massive volume of wastewater generated in cities is disposed of in two primary ways: either treated through public investments in piped sewerage systems and wastewater treatment plants, or through private investments in septic tanks, pit latrines and other infrastructure. In most low-income developing countries, capital investments in wastewater infrastructure is lacking, resulting in a patchwork of private and community solutions through on-site waste disposal.

There is currently no comprehensive data available on this indicator.

Enablers and barriers

We also monitor change by tracking a critical set of 13 enablers and barriers enabler or barrier that can help spur or impede change. Explore the data and learn about key actions supporting systems change.

Improve professional management of municipal solid waste utilities

Daily total weight of solid waste generated within municipal jurisdictions

The estimated total weight of solid waste generated daily by households and commercial establishments varies by city but is rapidly growing, especially in developing countries.

The worldwide amount of waste generated per person ranges from 0.11-4.54 kilograms/day, varying in line with the level of economic development in a given city. Due to a lack of adequate policy frameworks, institutional capacity and available financing, many cities in developing countries do not currently manage waste in an environmentally safe manner. In particular, the solid waste ecosystem infrastructure requires substantial capital investments.

Progress toward zero-waste outcomes is signaled when a city adopts and enforces circular economy policies, which incorporate three principles: eliminate waste and pollution by reducing resource usage; recycle and reuse products and materials; and regenerate nature rather than pollute land and water bodies with municipal wastes.

Currently there are no comparable city-level measurements of how municipal organic waste value chains can lead to circularity in resource usage through methane capture. Total citywide waste weights are estimated by multiplying average waste generated per person by the city’s total population. However, new technologies, such as inexpensive electronic sensors connected through Internet of Things (IoT) and big data analytics, could potentially be leveraged to improve data-gathering and tracking of waste supply chains. Value could be extracted through either methane capture or composting.

There are currently no specific, globally agreed-upon targets for reducing municipal waste. Current trends suggest that urban per-person waste generation in developing countries will reach at least the current worldwide average of 0.74 kg per person by 2030 (with overall volumes increasing because of urban population growth). With the endorsement of the international community and agreement of city leaders, a target could be set to slow down waste generation in each jurisdiction, increase circulation of materials through reuse and recycling, and track methane capture and regeneration of the local ecosystem.

Number of countries that completed zero-waste policy reforms

The absence of an adequately funded and professionally managed solid waste management system results in a large informal group of de facto waste service providers.

In many developing countries, informal waste pickers perform several waste management functions that are properly regarded as the responsibility of local governments. Some recycle household wastes such as paper and plastics, while others focus on dumpsites and landfills to selectively harvest discarded items that have recyclable value. Another group consists of septic tank and pit latrine emptiers, again in situations where this service simply cannot be provided in a timely manner by municipal agencies.

These people represent the poorest of the urban poor, struggling for living wages, working under highly unsanitary conditions and frequently littering urban ecosystems with non-recyclable wastes. The World Bank estimates that there are about 24 million urban waste-pickers working in developing countries worldwide. Eighty percent of these people provide informal but vital waste management services, and constitute about 1% of urban employment in many countries.

Policy reforms have the potential to significantly change the roles of informal workers and improve their lives. Brazil’s 2010 National Solid Waste Policy, for example, recognized the role of informal waste-pickers as low-income participants who are engaged in “recyclable material collection, sorting, processing, transformation and commercialization.” Through policy reforms, municipal governments are incentivized to support organizations such as recycling cooperatives to enable these informal workers to earn living wages, as in Morocco.

There is currently no comprehensive data available on this indicator.

Effective management of waste

Share of onsite septage volume disposed by informal latrine emptiers

Onsite sanitation places the onus on individual households to ensure that human waste is removed in a timely manner when a septic tank or pit is full. This service is often provided by informal sector workers, heightening health risks and often leading to degradation of the local ecosystem.

Onsite sanitation describes the use of pit latrines, septic tanks, aqua privies, and other systems that accumulate fecal sludge within underground receptacles. These storage areas for human wastes gradually digest the organic materials and emit methane on a continuous basis. They require regular desludging, and ideally the fecal sludge should be transported to treatment facilities (either wastewater treatment plants or dedicated fecal sludge treatment plants).

If the supply chain process is conducted through a transparent system of payment for services, the outcomes can be comparable with piped wastewater systems. However, in many cities in developing countries, informal workers are engaged in the physically demanding and socially degrading work of emptying the sanitary pits, which is often done onto the nearest water body or unused land.

Unless resources are available to build sewer systems in cities in developing countries, onsite sanitation systems will only grow. The trendline in this indicator therefore could go either up or down. There is currently no comprehensive data available on this indicator.

Percent of human waste collected through piped sewer systems

The share of liquid waste collected through piped wastewater collection and treatment systems provides an indicator of how effectively utilities collect and dispose of human and kitchen waste.

If the percentage of human waste collected through piped wastewater infrastructure is low, fecal sludge is generated principally through onsite sanitation systems. A fecal sludge collection and disposal process follows a similar process as in solid waste. Both processes share some common features, such as high organic content in the waste, but fecal sludge management is particularly degrading when the reliance is on manual emptying of septic tanks and pit latrines.

The trend in the percentage of human waste collected via piped sewer systems can either rise or fall, contingent upon the level of capital investment allocated to sewerage infrastructure at the city level.

Some municipal governments have tried to remedy the situation by encouraging public-private-community partnerships that can improve conditions. These include, for example, providing conservancy workers with vacuum trucks that can desludge the latrines and transport the contents to designated fecal sludge treatment and disposal sites. For instance, in Dhaka, Bangladesh, the municipal government procured a vacuum tanker and leased out the equipment to a private operator for cleaning onsite systems. In Kumasi, Ghana, the Kumasi Metropolitan Assembly invested in a dedicated treatment plant and shared some of the operating costs of collection and treatment. In Kampala, Uganda the local government and the water utility established partnerships with nonprofits, community groups and small businesses to improve access to sanitation services. This resulted in the amount of human waste treated increasing by more than 30 times between 2003 and 2015, despite barely increasing sewer connections in the city.

Raise awareness and improve zero-waste programs

Number of cities that have zero-waste management programs

City networks and local leaders can serve as important advocates and messengers for zero-waste solutions.

Stakeholders around the world have increasingly recognized the importance of implementing zero-waste strategies. United Nations (UN) Secretary-General António Guterres presided over the first International Day of Zero Waste at a meeting of the UN General Assembly on March 30, 2023. He also announced the formation of the Advisory Board of Eminent Persons on Zero Waste. Also at the global level, the Global Methane Initiative supports a Zero Waste and Organic Cycle initiative in partnership with non-governmental organizations to better capture methane from organic waste.

National policy frameworks that detail zero-waste strategies also play a crucial role in facilitating the creation of municipal action plans with specific zero-waste objectives. Countries are increasingly adopting national policy frameworks for solid waste management and methane capture, and other aspects of transition to zero-waste cities.

At the same time, the potential impact of leadership at the city level is evident through initiatives like the C40 Pathway Towards Zero Waste, “a city-level strategy that supports Global South cities to improve waste management practices and reduce methane emissions.” Signatories as of 2023 include Accra, Amman, Buenos Aires, Curitiba, Dar es Salaam, Dhaka South, Durban, Ekurhuleni, Freetown, Nairobi, Quito, Rio de Janeiro and Tshwane. These cities have committed to reduce their emissions using indicators that are consistent with C40’s Towards Zero Waste Accelerator.

There is currently no comprehensive data available on this indicator.

Number of cities implementing restrictions on single-use items and non-recyclable materials

Among single-use items, plastics have been a significant source of pollution. Many countries have banned single-use plastics, but other non-recyclable materials remain in circulation that require attention at the city level.

Non-recyclable inorganic waste includes single-use plastics, packaging materials, wet paper, plastic straws and even coffee pods. National regulatory agencies such as the U.S. Environmental Protection Agency have developed detailed regulations to be applied at the state or city level. The European Union has similarly issued waste directives, based on the waste hierarchy principles and aimed at minimizing waste flows to landfills, and has implemented restrictions in some cities.

Some developing countries have adopted similar regulations but enforcement is often a challenge. Mismanagement of these wastes has become a serious health and environmental issue in many developing countries.

There is currently no comprehensive data available on this indicator.

Establish a Monitoring, Reporting and Verification (MRV) system

Number of cities that have launched zero-waste programs focusing on methane capture evidence

The digital revolution is generating vast amounts of geo-referenced data that can be utilized by regulators and service providers for tracking and managing methane emissions from urban wastes, which could enable cities to significantly reduce their carbon footprints.

There are growing opportunities to use digital technologies to monitor methane from waste because electronic sensors have become ubiquitous, now present in infrastructure, vehicles and mobile telephones. Connecting these sensors through the Internet of Things (IoT) vastly enhances the opportunity for big data analytics to assist policymakers in tracking methane capture trends.

For example, the California Air Resources Board oversees and supports emitters implementing a methane reduction program based on the principle of “measuring what needs to be managed.” This involves a tiered observation system that “conducts measurements at many different scales to identify emission sources,” including satellite-based remote sensing mechanisms that can be used to identify high-methane-emitting geographies, which can in turn be validated by ground verification, utilizing existing air quality modeling data and regional inventory analysis.

High-resolution observations of atmospheric methane concentrations are also now available from several platforms, such as the European Space Agency, the World Bank and the Global Methane Initiative. World Bank applied research, for instance, has developed an easily-updated template for tracking atmospheric methane (CH4) concentrations at local and regional scales, with resolution at 2.5 square kilometers. This open access database enables the prioritization of actions to reduce methane emissions from the waste subsectors whose spatial distributions are highly non-uniform across and within countries.

Once this information is ground-truthed by data collection through sensors and by modeling, an accurate sensor-based digital dashboard could provide the basis for creating a digital twin that is an interactive virtual replica of a waste collection and disposal system made possible by connecting electronic sensors. This would provide an automated source of reliable information accessible to all stakeholders.

There is currently no comprehensive global data available on this indicator.

Number of city-level zero-waste campaigns involving civil society organizations and occurring on a monthly basis

Community engagement and buy-in are critical in fostering successful zero-waste campaigns.

Media reports and discussions of the need for zero waste on social media indicate the extent of community engagement and political buy-in for the concept of promoting zero waste. For instance, the success of India’s Swachh Bharat initiative to construct 100 million toilets has been attributed to a sustained campaign of raising awareness that included mobilizing Bollywood celebrities from television, cinema, radio and social media.

Gauging the level of community and leadership engagements helps indicate how far zero-waste values have been internalized by city stakeholders.

There is currently no comprehensive data available on this indicator.

Access to substantial long-term capital flows

Per capita availability of capital funds from national, state and municipal levels

Zero-waste investments can have benefits that extend beyond city bounds, as, for example, pollution often has adverse effects on an entire geographic region or larger ecosystem.

Zero-waste investments represent a public good that extends beyond a city, as pollution often has adverse effects on a geographic region or larger ecosystem. Any successful program therefore requires committed funding in the form of public finance, private finance and cost recovery from service users.

Solid waste management is an expensive, capital-intensive activity and typically absorbs a larger portion of a city’s budget in low-income countries compared to cities in more advanced economies.

Climate funds that prioritize capturing methane and other greenhouse gasses can attract additional funding if investors can be convinced that the institutional and regulatory structures — including contributions from higher levels of government — signal an adequate national commitment to the program. National policies remain key enablers for local actions.

There is currently no comprehensive data available on this indicator.

Number of cities with volume-based waste collection fees or other incentives

Cost recovery from users and the extent to which user fees are indexed to inflation rates inform potential investors of the economic health of the city waste management system.

The chronic financial challenge faced by cities in all income categories is how to cover operational expenditures for labor, fuel and the servicing of equipment. The city of Istanbul, for example, allocates 58% of waste management operational costs toward labor wages and another 31% toward fuel with only 11% available to amortize past loans or update equipment.

With inflation and rising energy costs, the ability of a municipal government to finance basic operations becomes limited over time unless it is able to increase revenues either through taxes or waste-service fees. In 2020, average annual user fees in sampled cities of Organisation for Economic Co-operation and Development (OECD) and upper-middle-income countries were over $80, while in South Asia it was $34 and in Africa it was between $10 and $40, according to the World Bank. In most developing country cities, the political will to raise user fees for waste management is absent. Cities like Curitiba, Brazil, have adopted incentives to engage communities in waste management by creating reliable incomes for the poor through recycling, providing green bus tickets, and more.

There is currently no comprehensive data available on this indicator.

Annual flow of international funding toward waste management

Implementing a zero-waste program requires a substantial commitment of concessional financing, including from voluntary carbon markets. However, thus far, the flow of international finance to this sector — even from official development assistance (ODA) — has been limited in scope.

Zero-waste programs require significant upfront investment to streamline systems for collection, conveyance and disposal, including systems designed for the capture of methane. Some of these aspects require improved institutional processes and regulatory oversight. Others — notably methane capture projects and the regulatory oversight — require private financing that is currently unavailable. Potential investors are often discouraged by the perceived political risks inherent in long-term engagement with city-level stakeholders.

While private financial flows have been absent, official development assistance (ODA) has been largely directed toward cities, with a bias toward cities in upper-middle-income countries. The World Bank, which is the largest international financier of solid waste management infrastructure, directed over $3 billion in financing to middle-income countries between 2010 and 2020 for waste management. Tanzania was the only low-income country that received financing from the World Bank for waste management in that period.

There is currently no comprehensive data available on this indicator.

Number of registered companies with environmental, social, governance (ESG) commitments to zero-waste targets

As of 2023, 10 of the largest multinational companies have made environmental, social and governance (ESG) commitments, as determined by the Science Based Targets initiative.

As of 2023, 10 of the largest multinational companies have made environmental, social and governance (ESG) commitments, as these are determined by the Science Based Targets initiative.

The current practice is to only list individual company commitments to zero wastes from its environmental, social and governance (ESG) budget; such companies include Unilever, Proctor and Gamble, Pepsi Cola and Coca Cola. To get a complete picture on private sector engagement to achieve zero-waste targets, it is necessary to account for the overall increase in registered companies including zero-waste targets in their ESG monitoring indicators is required. Since 2019, the number of companies has been steadily increasing.

Ensuring these funding sources are vetted through fully validated zero-waste indicators enables cities to access financing from these kinds of business enterprises.

Transition to circularity in resource usage

Annual renewable energy generation through methane capture from urban wastes

Successful methane capture signifies sustainable reductions in organic wastes generated by a city. The potentials for renewable energy generation from urban wastes are well recognized, but the volume of urban wastes currently generating renewable energy is largely in OECD and middle-income cities.

The actual amount of urban organic wastes repurposed for renewable energy generation predominantly occurs in cities within Organisation for Economic Co-Operation and Development (OECD) countries and those at middle-income levels. Typically, the heat from combustion of the wastes generates steam, which in turn produces electricity through turbogenerators. This process also relieves landfills of significant volumes of wastes that would have otherwise ended up there.

Waste-to-energy technologies can therefore convert non-recyclable and organic wastes into energy that can then be fed to the electricity grid, or be used as an alternative fuel for automobiles (as compressed natural gas). Methane capture is the significant climate co-benefit from this process.

There is currently no comprehensive data available on this indicator.

Data Challenges

Data gathering in a format that would assist this shift would require global acceptance of a methodology that systematizes measurements, reporting and verification through the leadership of the United Nations and other global advocates for climate.

This shift is subject to a series of data challenges because of an absence of standardization.

Photo credits

By Ivan Bandura via Unsplash