We all do it, some of us more than others. But how many of us think about the impact we are having on the environment, the health care system, and indeed the global economy every time we flush the toilet? 

Governments across the globe have been accused of “turning a blind eye” to the billions of dollars being drained from economies and the great cost to agriculture, fisheries, and health systems suffered as a result of sewage and wastewater mismanagement.

These economic and social burdens – suffered as a direct result of poor sewage treatment – have all been laid bare in a new report launched at the World Ocean Summit in Japan this week, revealing the extent of the reverberations felt of a mismanaged sewage system, including upon depleting food sources and overwhelmed health care systems globally.

The study – brought together by the ocean health initiative Back to Blue in partnership with the Ocean Sewage Alliance – has calculated the cost of wastewater management inaction across five low, middle, and high-income countries; Brazil, India, Kenya, the Philippines, and the UK.

It marks a milestone moment for the subject, being the first time that both sanitation and the environment have been presented from an economic perspective on the global stage. The World Ocean Summit has hosted not one but two sessions on the subject during its two-day conference this week, presenting what industry hopes could be a step-change in the global approach to addressing the subject of sewage head-on. 

It’s no secret that untreated or inadequately treated wastewater released into the environment is a major source of pollution and disease. The report reveals that in some of the most extreme cases, such as in Kenya where some 15.5 million people are still exposed to contaminated drinking water and 84% of the population relies on on-site sanitation, as little as 11% of wastewater is adequately treated. As a result, improperly treated wastewater enters rivers, oceans, and drinking water supplies with severe consequences.

The study finds that contaminated water used for irrigation is severely reducing crop yields while fisheries are collapsing due to polluted rivers and coastal waters. In the last year, Kenya has lost 5% of its fishery value to sewage mistreatment.

in India, those losses are more severe, with some $2.15 billion knocked off its fishery sector. India’s fishing industry is heavily dependent upon freshwater sources, many of which are severely polluted.

“It’s no new revelation that wastewater has serious consequences, but it is not often thought of as an economic burden, nor as a burden on health systems, but as an environmental problem,” said Richard Damania, chief economist of the Sustainable Development Practice Group at the World Bank.

“Inadequate sewage systems are leaving populations sick and starving, all the while costing the economy billions. Clean water systems are necessary for human health, strengthening livelihoods, and fuelling economies.”

Back to Blue has been able to calculate the economic and social costs endured by agricultural, fisheries, and health sectors in each of the five countries examined. 

Brazil’s agricultural sector suffers the greatest losses, with untreated wastewater leading to decreased yields of staple crops like corn and soybeans. As the world’s largest exporter of soy and sugarcane, its economy loses $16 billion a year from these crops, jeopardising food security, exports, and sustainability.

India, meanwhile, faces the highest financial losses from fisheries collapse, with contaminated waterways costing its fisheries sector more than $2 billion each year. 

In the UK, greater emphasis is on the environmental impact of sewage mismanagement, particularly the increasing frequency with which water companies are allegedly exploiting an infrastructure that allows them to release untreated wastewater into rivers during periods of heavy rainfall to prevent sewage backup in people’s homes.

This is having a detrimental impact on the UK’s biodiversity and the industries it supports. In 2017, an emergency sewage overflow killed approximately 5,000 fish in the River Great Ouse, while fish deaths from water pollution have surged. Between 2023 and 2024, some 216,000 fish deaths were recorded – a fivefold increase from the previous year.

The wastewater discharge data used in the report does not, however, account for the wastewater discharged through the Combined Sewer Overflows system, meaning real-world impacts are likely far worse than estimates suggest.

Chief among the concerns of all this sewage mismanagement, of course, is its impact on human health. Diseases associated with inadequately treated sewage present a significant health risk resulting in substantial economic losses. 

While most cases can be mild, some are life-threatening, causing hospitalisations that further strain healthcare systems, incomes, and economies. This is a particular concern in countries of lower economic income, where current lack of infrastructure exposes populations to far greater risks.

Dr Amelia Wenger, conservation scientist and water pollution programme lead at Wildlife Conservation Society, said: “It is often the local communities that suffer the most from sewage pollution. Lost wages and expensive medical bills put an enormous strain on families.

“Yet these financial losses caused by poor infrastructure and failed policies are entirely avoidable. This report puts a clear economic price on these consequences – which can drive action to bring about meaningful change.”

The report highlights, in real terms, the economic burdens suffered by nations over the course of the last year owing to mishandled sewage. The potential continued impact across the globe, of course, is a far weightier figure. 

According to the Reef Resilience Network, it’s estimated that coral reefs provide $375 billion a year around the world in goods and services, providing a crucial ecosystem for marine life that helps fuel a global fisheries industry. 

While projects around the world continue to address the symptoms of mismanaged sewage through conservation and restoration efforts, the report maintains that addressing the issue at the source will provide huge benefits both near-term and long-term.

It is hoped that by presenting the economic impact of mismanaged sewage governments and businesses will be better informed of those benefits.

“There’s lots of reasons why we’re not addressing sanitation, but it’s not because people are fundamentally opposed to the idea – it’s just that it’s expensive,” Dr Wenger told Oceanographic Magazine.

“It requires system strengthening, it’s not just a technology fix, it requires governments to prioritise it. But at the moment, nobody is.”

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