In upper income countries, these Phases occurred over several decades or even centuries, tracking industrialisation and technological advances. This enabled development of infrastructure such as wastewater treatment facilities and capacity to monitor and regulate contaminants in Phases 1 and 2. Today, many lower- and middle-income countries (LMICs) are facing pressures from compressed and overlapping water pollution phases. Sanitation challenges from rapid urbanisation coincide with industrial development fueled by outsourcing of manufacturing and agriculture from UICs to LMICs. With even the highest income countries struggling to reduce Phase 2 and 3 pollutants, it is unsurprising that many countries lack the resources to address the multiplicative pressures of all three Phases simultaneously.
‘Invisible’ but impossible to ignore
With water technologies at an all-time high, what accounts for this lack of progress and even degradation of water quality worldwide? While water quantity challenges have attracted attention due to their visually dramatic manifestation (floods, drought), water quality issues are often inconspicuous or invisible. Several converging factors are making the three Phases of water pollution increasingly visible and impossible to ignore:
We are polluting more rapidly and diversely than ever
Thousands of pollutants now exist at detectable concentrations in the environment. Agricultural applications (fertilisers, pesticides, pharmaceuticals) are increasing worldwide, and freshwater environments are affected by salinization due to irrigation and sea level rise. Meat consumption continues to increase, with its associated nutrient and pharmacological burdens. Surges in pollution are generated by unforeseen global crises, such as plastic pollution linked to personal protective equipment against COVID-19 (Prata et al., 2020).
Environmental change and globalisation are focusing impacts of pollution in space and time
Land use and climate change are short-circuiting the water cycle (Levia et al., 2020). Extreme storms and altered surface and subsurface drainage accelerate pollution transport and reduce ecosystem removal processes. Moreover, human disturbance can result in long-term release of legacy contaminants (Van Meter et al., 2018). At the same time, abrupt increases in global trade have supercharged global transport of livestock, crops, manufactured goods, and waste. This has resulted in imbalances in nutrients, metals, plastics, and other contaminants. As LMICs, typically have less capacity to treat waste, this results in more water pollution per tonne and much higher human exposure.
Growing pollutant knowledge has improved regulation with more stringent standards
Although the widespread detection of long-banned pollutants such as PCBs could signal worsening pollution, often it reflects improved measurement capabilities. Sensitive methods now detect a wide array of pollutants at low concentrations. In some cases, our failures are a consequence of better-informed and increasingly stringent standards rather than absolute decreases in water quality.
From crisis to solutions
The last two centuries of water problems and solutions demonstrate that we must be proactive in managing river pollution rather than create new pollution legacies for future generations. In the face of intermeshed phases of pollutants, we need compressed and overlapping solutions that:
Integrate understanding of human activity into holistic water management
To address complex water quality challenges, rivers and their hinterlands must be managed as connected systems. This requires improved understanding of linkages between human activities on the landscape and water quality across space-time scales. Knowledge of water science is needed to balance public expectations and inform policy. Short-term interventions may take decades to result in improvements, while mismanagement may trigger new issues far into the future (Van Meter et al., 2018).
Move beyond regulating individual chemicals
To date, most chemicals are regulated individually. This can initiate a legislative wild-goose chase whereby slight changes to chemical composition circumvent regulation. A new EU model is emerging whereby chemicals are regulated based on their combined impact, as opposed to individual compounds. For this approach to be effective for more emerging contaminants, we need improved knowledge of potential acute and chronic toxicity of multi-contaminant cocktails.
Leverage long-term and novel data sources
Environmental regulation has been informed by manual sampling and in situ monitoring. Insights from satellite imagery and unoccupied aerial vehicles are expanding monitoring in inaccessible areas, enabling detection of sources and consequences of pollution (Huang et al., 2018). Yet, there is a parallel need to extend long-term monitoring to track progress and ground-truth newer methods. However, these records’ integrity is threatened by declining funding for monitoring networks, inconsistent approaches to data collection and lack of open data sharing (Lovett et al., 2007). A combination of conventional and cutting-edge monitoring methods is needed.
Engage and empower communities and decision-makers
Working directly with impacted communities to monitor water quality improves observational capabilities and empowers local people (Nardi et al., 2021). Stakeholder engagement and citizen science initiatives can lead to improved decision-making and behavioural change.
Share knowledge to boost human wellbeing
If knowledge and management actions are aligned with well-designed, effectively implemented and enforceable regulations, we can illuminate invisible water challenges, producing healthier river environments for the benefit of ecosystems and society.
