Wastewater Pollution Introduction
Wastewater pollution is a growing threat to people and marine life and makes up the largest percentage of coastal pollution worldwide. ref Globally, an estimated 80 percent of wastewater – which includes human sewage – is discharged into the environment without treatment, releasing an array of harmful contaminants into the ocean and causing direct harm to people and coral reefs. ref Research shows that wastewater pollution often occurs in proximity to coral reefs around the world due to nonexistent or inadequate wastewater management. ref
Terminology: Sewage vs Wastewater
Sewage and wastewater are terms that are often used interchangeably, but there are important differences between the two. Sewage (human waste transported through sewers) is a major component of wastewater, which is a collective term for the used water of a community or industry. Wastewater contains dissolved and suspended matter from a variety of domestic, commercial, or industrial sources including chemicals, soaps, heavy metals, nutrients, and effluent from sewered and non-sewered systems (like septic treatment tanks).
We recognize that marine managers and practitioners are likely more familiar with the term sewage when considering the major impacts to coral reefs, however, we will be using the term wastewater throughout the toolkit since it accurately describes various sources of pollution impacting coral reefs. Using consistent terminology helps facilitate partnerships with other sectors, like the sanitation sector.
Wastewater Pollution Around the World
While major coastal cities in low-income countries are a significant source of wastewater pollution, high-income nations are not exempt. The United States alone annually discharges more than 1.2 trillion gallons of effluent (including untreated raw sewage, stormwater runoff, and industrial waste) into waterways every year. ref
Documented coastal wastewater pollution in 104 of 112 areas with coral reefs. Source: Wear and Vega Thurber 2015
When wastewater enters the ocean and mixes with seawater, pollutants are dispersed and diluted. This has led to a persistent assumption that “the solution to pollution is dilution”. However, increases in novel, unregulated contaminants as well as increasing volumes of wastewater limit the ocean’s capacity to dilute those contaminants and render the consequences of pollution more severe. Geography, population, infrastructure, and climate change can all influence the severity of wastewater pollution impacts. Wastewater pollution can result in (Our Shared Seas):
- Physical and biological damage to coral reefs, seagrasses, and salt marshes. ref
- Loss of coastal ecosystem services, like erosion control, storm buffering, and nursery grounds for juvenile fish. ref
- Harmful algal blooms that kill marine life, close beaches, and cause human disease. ref
- Human and animal diseases resulting from pathogens, heavy metals, and toxic chemicals. ref
- Contaminated fisheries, increased fish and shellfish mortality, and reduced species diversity. ref
Watch the webinar on Addressing the Threat of Ocean Sewage Pollution:
Sanitation and Wastewater
Although progress is being made, much of the global population does not have access to adequate sanitation to protect public health. According to the World Health Organization, in 2020, 45% of the world's population did not have access to safely managed sanitation services, and 6% were practicing open defecation. ref
Breakdown of sanitation coverage by region (top left) and sanitation ladder definitions (top right). Global sanitation coverage from 2015-2020 (bottom). Source: JMP
Water, Sanitation, and Hygiene (WASH) Sector
Contact with human waste represents an urgent challenge and has led to the development of the Water, Sanitation, and Hygiene (WASH) sector. The WASH sector is a field dedicated to protecting public health and the environment by providing equitable access to safe, reliable drinking water and sanitation services. There are many organizations that work toward this goal, including:
- Global agencies like the World Health Organization (WHO), United Nations Children's Emergency Fund (UNICEF), and the World Bank.
- Government agencies like Centers for Disease Control and Prevention (CDC) and United States Agency for International Development (USAID).
- Nonprofit organizations like the WHO international Reference Center on Community Water Supply (IRC) and Sustainable Sanitation Alliance (SuSanA).
While the issue of wastewater pollution can seem daunting, the global effort to address this challenge has resulted in a steady increase in the number of people with access to safe sanitation over the past five years. This progress can be attributed to:
- Increased recognition of the importance of sanitation.
- Technological advances in improved sanitation systems, and
- More organizations helping communities access these systems.
As awareness, research, and funding continue to grow and the WASH sector’s efforts expand, marine managers can help shape these efforts to benefit both people and reefs.
