What If Your Waste was actually Worth Something?
Once you flush, your waste travels through a network of underground pipes that most cities have spent decades and
Every day, without thinking about it, you flush a toilet. The water swirls, the bowl clears, and you walk away. That moment, that completely ordinary, forgettable moment, is actually the beginning of the wastewater treatment industry: one of the largest and least talked about sectors in global commerce.
The journey nobody thinks about
Once you flush, your waste travels through a network of underground pipes that most cities have spent decades and billions of dollars building. It moves through local sewers, into trunk mains, and eventually arrives at a wastewater treatment plant. A large facility might process hundreds of millions of litres every single day. Most people have never seen one.
At the plant, solids are separated from liquids. The water goes through multiple stages of filtration, biological treatment, and chemical processing before being returned to a river, a bay, or in some cases a drinking water reservoir. The solids, known in the industry as biosolids or sewage sludge, get handled separately. And this is where things start to get commercially interesting.
A quiet industry doing enormous work
The wastewater treatment industry was valued at around $370 billion in 2025. By 2034, it is projected to reach more than $650 billion, growing at roughly 6.5 percent per year. That is not a niche sector. It is one of the most consistently expanding industries on earth, driven by population growth, rapid urbanisation across Asia and Africa, and tightening environmental regulations in nearly every major economy.
The companies doing this work are large and largely invisible to the general public. Veolia, the French multinational, reported revenue of EUR 44.7 billion in 2024. It operates across 56 countries with 215,000 employees and provides drinking water to 111 million people. In a single year, the company treated 65 million tonnes of waste and produced 42 million megawatt hours of energy from the process. By almost any measure, it is one of the most operationally significant companies in the world. Most people could not name it.
Other major players include Xylem, Ecolab, and Black and Veatch, all of whom design, build, and operate treatment infrastructure for governments and industrial clients. The business model is stable by design. Municipalities sign long-term contracts with private operators, often running ten to twenty-five years, under public-private partnership arrangements known in the industry as design-build-own-operate models. Revenue is recurring, contracts are long, and the service cannot be switched off. For investors hunting predictable cash flows, that combination is nearly impossible to find elsewhere.
Turning what you flush into something worth selling
The real commercial story is not in the treatment. It is in what comes out the other side.
Biosolids, once treated, are rich in nitrogen, phosphorus, and organic matter. They are, in other words, fertiliser. According to the National Biosolids Data Project, over half of all wastewater solids generated in the United States are now recycled as fertiliser or soil amendments rather than going to landfill or incineration. For the treatment facilities producing them, this creates a revenue stream from what was previously a disposal cost.
Energy recovery is the other major value driver. As organic material breaks down in large sealed tanks called anaerobic digesters, it releases biogas, primarily methane. The US Environmental Protection Agency reports that over 1,200 water resource recovery facilities in the United States now operate anaerobic digesters. More than half of those facilities use the biogas they capture as an energy source rather than burning it off as waste.
The numbers at individual plants tell the real story. Boston’s Deer Island Wastewater Treatment Plant, the second-largest facility in the United States, runs 12 anaerobic digesters that reduce sludge volume by around 60 percent and produce biogas continuously. That biogas powers steam boilers and a turbine generator, covering more than 97 percent of the plant’s thermal energy demand and around 17.5 percent of its electricity needs. The savings amount to roughly $17.5 million in energy costs per year. The digested sludge itself is piped to a separate facility, dried into pellets, and sold commercially as fertiliser. One plant is simultaneously a wastewater processor, a power generator, and a fertiliser producer.
Facilities in Scandinavia and the United Kingdom have pushed this further, using advanced digestion technologies to reach full energy neutrality. Some now produce more electricity than they consume and sell the surplus back to the grid.
The liability hiding inside the revenue stream
The biosolids business comes with a serious and growing commercial risk that investors and operators cannot afford to ignore.
PFAS, commonly called forever chemicals, are synthetic compounds found in everyday products from non-stick cookware to food packaging. They do not break down during wastewater treatment. That means they accumulate in biosolids, and when those biosolids are spread on farmland as fertiliser, they can move into soil, groundwater, and the food chain. It is one of the most pressing liability questions now facing the wastewater treatment industry.
In February 2024, five farmers in Johnson County, Texas, filed a lawsuit against Synagro Technologies, one of the largest biosolids managers in the United States. The company processes 6.5 million tonnes of biosolids annually under contracts with more than 1,000 wastewater facilities across North America. The farmers alleged that Synagro’s biosolid fertiliser contaminated their water, their soil, and their livestock. Testing found PFAS concentrations far above EPA health advisory levels in soil samples and in the tissue of fish and livestock on affected properties.
The legal exposure is spreading. By early 2026, at least sixteen US states had enacted statutes or regulations addressing PFAS in biosolids. Maine banned land application entirely after more than sixty farms were found to have unsafe contamination levels. Connecticut followed with its own ban. More than 350 PFAS-related bills were introduced across US state legislatures in 2025 alone. For operators whose business model includes selling biosolids as a revenue-generating product, that regulatory shift is not a distant threat. It is already changing what is commercially viable and what is not.
Why institutional money is pouring in
Despite the PFAS uncertainty, the broader investment case for the wastewater treatment industry has never looked stronger. In 2025, global infrastructure fundraising hit a record of nearly $200 billion, a 60 percent increase on the prior year, according to McKinsey. Water assets were a significant driver of that momentum.
According to a 2025 survey by White and Case, infrastructure funds deployed around $1.3 billion each into the water sector in 2024, approaching the levels of public sector investment. Ninety-six percent of respondents said they planned to maintain or increase their water investments in 2025. KKR has been among the most active, building water-focused platforms including Axius Water, which focuses on nutrient management in wastewater treatment, and exploring a multi-billion pound investment in Thames Water in the United Kingdom. In January 2025, Ridgewood Infrastructure closed its Water and Strategic Infrastructure Fund II at $1.2 billion, surpassing its initial target.
The attraction is structural. Water and wastewater assets generate contracted, inflation-linked revenues. They serve non-discretionary demand. They are, by definition, monopoly services in the geographies they serve. In a period of volatile equity markets and geopolitical uncertainty, those characteristics command a premium.
Water scarcity as a business tailwind
There is a broader commercial logic tightening behind all of this. Water is becoming scarcer in more places, faster than most policy discussions acknowledge.
The UN estimates that global freshwater consumption doubles roughly every twenty years as populations grow and industry expands. More than 40 percent of the world’s population already lives in regions experiencing significant water stress. As scarcity intensifies, the value of treated and recycled water rises, and so does the pricing power of the operators producing it.
Singapore’s NEWater programme illustrates what that looks like in practice. The city-state, which has almost no natural freshwater of its own, built a system that takes treated used water through microfiltration, reverse osmosis, and ultraviolet disinfection to produce water that exceeds World Health Organisation drinking standards. The programme now has a supply capacity of 760,000 cubic metres per day and can meet up to 40 percent of Singapore’s current water needs, with a target of 55 percent by 2060. That is not environmental policy. It is a government reducing a strategic dependency on imported water through the same logic a business uses to reduce reliance on a single supplier.
A newer pressure is making the scarcity argument more urgent in unexpected places. AI data centres are extraordinarily water-intensive. Google reported that its data centres consumed 6.1 billion gallons of water in 2023, a 17 percent increase year on year. As data centre construction accelerates globally, the demand for treated and recycled water is increasing in regions that were not previously considered water-stressed. That is a structural tailwind for the wastewater treatment industry and the operators who can supply it.
The industry that holds things together
The wastewater treatment industry is more complicated than it looks. On one side, you have long-term contracted infrastructure assets generating stable returns and growing institutional interest. On the other, you have a fertiliser revenue stream under regulatory and legal pressure from PFAS, and an energy-from-waste model that still has room to mature. In the middle, you have an accelerating global need for water that is making everything the sector produces more valuable.
It is an industry that runs underground, out of sight, without recognition. It employs engineers, lawyers, financial analysts, agronomists, and operators. It connects to agriculture, energy, real estate, and technology in ways that are only starting to be priced into markets.
The value was always there. It is the rest of the world that is catching up to it.The question now is who gets in before the rest of the market does too.
Sources
- Veolia Environnement. *2024 Annual Results.* Business Wire, February 2025.
- McKinsey and Company. *Infrastructure: Investing to Support Global Growth, Global Private Markets Report 2025.*
- White and Case. *Currents of Capital Report 2025: Rising Tide.*
- PUB, Singapore’s National Water Agency. *NEWater.*
