Protecting Oceans Begins Upstream
Why source-to-sea is the missing layer in blue finance.
Much of the harm done to the ocean does not begin there. Around 80% of marine po lution originates from land-based activity, and an estimated 11 mi lion tonnes of plastic enter the ocean each year (UNEP, 2026a). Investor attention, by contrast, sits largely at sea. In the European Commission's 2026 BlueInvest survey, shipping and ports (46%) and blue renewable energy (41%) ranked highest for financial potential (European Commission BlueInvest, 2026).
A growing market
The blue economy is expanding. In 2025, Phenix Capital tracked 186 blue economy funds with €69 billion in commitments, up from 26 funds in 2015 (Phenix Capital, 2025). The European Commission groups it into seven established sectors: marine living resources, marine non-living resources, marine renewable energy, port activities, shipbuilding and repair, maritime transport and coastal tourism (European Commission, 2025). However, none of them covers the prevention of pollution on land. This gap reflects a broader funding imbalance, as SDG 14 is among the least funded goals, with less than US$10 billion invested between 2015 and 2019 against an estimated US$175 billion a year needed to achieve it by 2030 (UNEP, 2026b).
Source-to-sea management treats land, freshwater, estuaries, coasts and the open ocean as one connected system. The approach was formalised by the Action Platform for Source-to-Sea Management, a network launched in 2014 and hosted by SIWI, whose partners include UNEP, UNDP, IUCN and IOC-UNESCO. Its practitioners' guide builds on a framework developed for the Global Environment Facility to manage the flows that link upstream activity to coastal outcomes (SIWI, 2019). For investors, it offers a way to trace an upstream intervention to a measurable downstream result, rather than treating water and ocean outcomes as separate markets.
Blue capital is growing, but Wellers Impact’s market mapping finds it fragmented. Geographically, it is concentrated in OECD economies, Europe in particular, rather than the Global South. By sector, it goes mainly to fisheries, aquaculture, blue technology, ports and conservation. It tends to fund early-stage ventures or large infrastructure, rather than growth-stage companies with proven revenue that need capital to scale. It also arrives as grants, concessional debt or late-stage equity. Appetite for emerging-market SME risk remains limited. The market does not lack blue capital in aggregate. It lacks capital structured for emerging-market companies that prevent pollution upstream.
WASH capital, aligned to SDG 6, focuses on water access, sanitation and service delivery, and rarely follows outcomes downstream. The result is a visibility gap: upstream sanitation and waste businesses fall outside blue mandates, while WASH funds rarely count their ocean benefit. Between the two sits a growth-stage missing middle: small and medium-sized enterprises (SMEs) in the Global South seeking US$0.5 million to US$5 million. Many already intercept pollution or treat wastewater at source, with paying customers and scalable models. They are too mature for grants, and too small or complex for infrastructure finance. Reaching them depends on three components coming together: recognition that upstream businesses deliver ocean outcomes, vehicles able to source them, and growth capital on terms that fit their stage.
The missing pipeline
Investor appetite exists and is shifting upstream. In the BlueInvest survey, the share of investors citing water management's financial potential rose from 6% in 2023 to 38% in 2026, placing it third of eight sectors (European Commission BlueInvest, 2023; 2026). Yet few vehicles invest upstream in emerging markets.
Water Unite Impact (WUI) invests in water sector SMEs using a Water+ framework. Three of its five pillars focus directly on ocean outcomes: sanitation services, wastewater circularity and plastic waste circularity. Because investees report KPIs quarterly, such as tonnes of sludge treated or plastic collected, those metrics provide a measurable indicator of activity that reduces the risk of pollution reaching rivers and coastal waters.
Four pathways to the sea
Four pathways carry the largest land-based pressures to the coast, and each contains growth-stage businesses addressing them.
Coastal sanitation and faecal sludge
In 2015, human wastewater delivered more than 6 million tonnes of nitrogen to coastal waters, exposing 58% of the world's coral reefs and 88% of its seagrass beds (Tuholske et al., 2021). In Kenya, less than 10% of human waste is treated before it enters the environment (UNEP, 2018). Along the coasts of Kenya, Tanzania and Mozambique, untreated faecal sludge flows into rivers, mangroves and reefs.
Sanivation, WUI's first investee in 2021, works where sewers do not reach. Its plants dewater, sterilise and heat faecal sludge from pit latrines and septic tanks into biomass fuel briquettes, sold to industrial customers as an alternative to firewood. On paper, it looks like a conventional WASH business, closing a sanitation gap on land. Its relevance to the ocean lies in where that sludge would otherwise go. Every tonne treated reduces the risk of nutrients and pathogens reaching rivers, mangroves and reefs, and over WUI's investment period Sanivation safely managed 6,203 tonnes (Wellers Impact, 2026b). Ocean funders have reached the same conclusion. In December 2025, the Global Fund for Coral Reefs and UNCDF agreed US$540,000 of financing to bring Sanivation's model to Malindi National Marine Park, to reduce the nutrient and pathogen loads entering its coastal waters (UNCDF, 2025).
Plastic and solid-waste circularity
More than 1,000 rivers carry around 80% of the plastic that rivers deliver to the ocean. Small urban rivers in coastal cities are among the worst polluters (Meijer et al., 2021). Intercepting plastic in those cities, before it enters drains and rivers, reduces the risk of it reaching the sea. Across the Global South, businesses are already building commercial models around this. In Kenya, for example, Mr Green Africa buys post-consumer plastic from 2,450 informal collectors and collected a recorded 4,526 tonnes in 2025 (Wellers Impact, 2026a). In Mexico, #tide México, now known as H2OLA, collects marine plastic through coastal hubs with support from the Global Fund for Coral Reefs (GFCR, 2026). In Indonesia, an accelerator backed by the Australian Government and the Alliance to End Plastic Waste has supported 85 plastic-waste ventures since 2022 (Australian Embassy Indonesia, 2025).
Industrial wastewater and resource recovery
Industrial effluent is the least visible pathway. In the countries that report on it, only 27% of industrial wastewater is safely treated (UN-Water, 2024). In the river basins of South and Southeast Asia, including Indonesia, Vietnam and Bangladesh, food processing, palm oil and textile industries line rivers that drain to estuaries and coasts. Treating that effluent at the factory, before it reaches the river, can turn a pollutant into a resource. In Indonesia, GREE Energy, which reports that 90% of the country's food processors lack proper waste treatment, converts their effluent into biogas and removed 5,072 tonnes of chemical oxygen demand pollutants in 2025 (Wellers Impact, 2026a).
Water resilience in coastal and island systems
Small island developing states and water-stressed coasts in the Caribbean, Pacific and Indian Ocean face a different pressure. Their challenge is too little freshwater, often met by desalination. These plants worldwide produce around 142 million cubic metres of hypersaline brine a day, and its disposal carries environmental costs (Jones et al., 2019). Here the pressure on the coast comes from infrastructure rather than upstream pollution, so the link to the source-to-sea theme is less direct. The concern, however, is the same: limiting what is discharged into shallow coastal waters. Flocean, a Norwegian-based company in the WUI portfolio, desalinates at depth using natural hydrostatic pressure below 400 metres. This avoids discharging brine into shallow and sensitive ecosystems and uses up to 50% less energy and 95% less coastal land than conventional desalination (Wellers Impact, 2026a).
Why Wellers Impact
Since 2021, the fund has screened more than 500 opportunities and made seven investments across water, sanitation and circular-economy businesses in the Global South.
The Sanivation exit shows the model at work. Risk-tolerant capital arrived when commercial investors could not engage, and in January 2026 PIDG committed US$3.3 million of equity (Wellers Impact, 2026b).
How LPs can engage
For blue economy investors, the upstream segment offers a way to reach pollution at its source. Wellers Impact works with investors through co-investment, allocations within the Water+ mandate and partnerships on sourcing and technical assistance.
“The ocean's health is decided upstream. Every tonne of sludge treated or plastic collected on land is pollution that never reaches the sea. Water Unite Impact has spent five years backing the businesses doing that work, and we see a clear role for blue economy investors alongside us.” - Neil Sandy, CEO
Wellers Impact welcomes conversations with investors working on pollution prevention, circularity and water infrastructure.
Australian Embassy Indonesia (2025). Prominent Indonesian entrepreneurs present solutions to plastic waste at IPPIN Indonesia Chapter Demo Day, 28 October 2025. indonesia.embassy.gov.au
European Commission BlueInvest (2023; 2026). BlueInvest Investor Reports.
European Commission (2025). The EU Blue Economy Report 2025.
GFCR (2026). #tideMéxico (H2OLA), REEF+ finance solutions. globalfundcoralreefs.org
Jones, E., Qadir, M., van Vliet, M. T. H., Smakhtin, V. and Kang, S. (2019). The state of desalination and brine production: A global outlook. Science of the Total Environment, 657, 1343–1356.
Meijer, L. J. J. et al. (2021). More than 1000 rivers account for 80% of global riverine plastic emissions into the ocean. Science Advances, 7(18).
Phenix Capital (2024; 2025). Blue Economy Impact Report. Fund counts reflect the Phenix database, not the full global universe.
SIWI (2019). Implementing the Source-to-Sea Approach: A Guide for Practitioners, which builds on GEF STAP, A Conceptual Framework for Governing and Managing Key Flows in a Source-to-Sea Continuum.
Tuholske, C. et al. (2021). Mapping global inputs and impacts from human sewage in coastal ecosystems. PLOS ONE, 16(11).
UNCDF (2025). GFCR and UNCDF launch new coral reef positive investments in Kenya.
UNEP (2018). Make 'em move: your bowels' hidden power.
UNEP (2026a), Source-to-sea approaches (unep.org, accessed October 2026), for both figures. The 80% estimate dates from UNEP's State of the Marine Environment report (2006). The plastic figure originates in The Pew Charitable Trusts and SYSTEMIQ, Breaking the Plastic Wave (2020).
UNEP (2026b). Ocean finance (accessed October 2026), citing World Economic Forum (2022).
UN-Water (2024). Progress on Wastewater Treatment: 2024 Update.
Wellers Impact (2026a). Annual Impact Report 2025.
Wellers Impact (2026b). Impact Investment Review: Water Unite Impact Completes Exit From Sanivation, May 2026.
ABOUT WELLERS IMPACT
Wellers Impact is an FCA-regulated impact investment firm based in the UK. The team's investment models are centred on using fair economics to pursue SDGs-aligned impact. Wellers Impact has two core business activities; real estate development in partnership with land-owning not-for-profits and Water Unite Impact. wellersimpact.com
This article is for informational purposes only and does not constitute an offer to sell, a solicitation of an offer to buy, or a recommendation of any security or any other product or service. Past performance is not indicative of future results. Impact investing involves risks, including the possible loss of principal. Wellers Impact is authorised and regulated by the Financial Conduct Authority (FCA).
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