Removing hormones from water requires a combination of treatment methods because no single technology eliminates them all. Natural and synthetic estrogens rank among the most potent endocrine-disrupting compounds found in municipal wastewater, and conventional sewage treatment plants remove many of them but let a stubborn fraction pass through, particularly the synthetic estrogen ethinylestradiol found in birth control pills.1PubMed. Fate and removal of estrogens in municipal wastewater Activated carbon, advanced oxidation with ozone, membrane filtration, and newer biological approaches each tackle the problem from a different angle, and the best results come from layering these strategies together.
Where the Hormones Come From
When people think of hormones in water, they usually picture pharmaceutical estrogen from contraceptive pills. That is part of the story, but not all of it. Municipal wastewater contains a cocktail of natural estrogens that every human excretes daily, including estrone, estradiol, and estriol, plus synthetic hormones from medications. Sampling at three treatment plants in southeastern Pennsylvania detected estrone in every plant, with estradiol and estriol showing up at two of the three, and the synthetic ethinylestradiol appearing at one.2PubMed. Free synthetic and natural estrogen hormones in influent and effluent of three municipal wastewater treatment plants
Agriculture is the other major contributor, and in some regions it dwarfs the human one. Livestock excrete large quantities of steroid hormones, and research in the United Kingdom estimated that a single dairy cow produces roughly a hundred times more estrogens than a single person on a body-weight-adjusted basis. The combined farm animal population in the UK likely generates about four times more estrogens than the entire human population, with dairy cows being the single largest contributor on the animal side.3PubMed. The potential steroid hormone contribution of farm animals to freshwaters, the United Kingdom as a case study These hormones enter waterways through direct excretion into streams, farmyard drainage, and manure-spread fields. Field studies have confirmed that estrogens from manure are mobile enough in soil and persistent enough to reach both surface water and groundwater.4PubMed. Manure-borne estrogens as potential environmental contaminants: a review
Concentrated animal feeding operations add a focused source. Wastewater lagoons at these facilities have been found to contain estrone, testosterone, and other steroid hormones, with some of those compounds leaching into shallow groundwater underneath the lagoons at concentrations up to hundreds of nanograms per liter.5PubMed. Occurrence of steroid hormones and antibiotics in shallow groundwater impacted by livestock waste control facilities
Why It Matters
The concern is not hypothetical. Steroid estrogens in sewage effluent have been directly linked to the feminization of male fish in English rivers. The Environment Agency of England and Wales found that the severity of feminization correlated with the proportion of treated sewage effluent in receiving waters, and concluded that the weight of evidence was sufficient to develop a risk management strategy for estrogenic effluents.6PubMed Central. Assessment of feminization of male fish in English rivers by the Environment Agency of England and Wales These effects extend beyond fish. A broad review of the evidence found that chemicals interfering with reproductive hormones are particularly pronounced in aquatic species including fish, amphibians, and birds, with laboratory experiments frequently confirming what field observations suggest.7PubMed. Impacts of endocrine disrupting chemicals on reproduction in wildlife and humans
For humans, the picture is less dramatic but still worth paying attention to. A systematic review examining estrogens as emerging contaminants from a global health perspective linked chronic exposure to contaminated drinking water with disrupted hormonal balance, increased cancer risk, fertility problems due to impaired sperm production, and complications during pregnancy.8PubMed Central. A Systematic Review of Estrogens as Emerging Contaminants in Water: A Global Overview Study from the One Health Perspective A separate risk analysis of estrogenic compounds in drinking water classified the non-cancer health risk as high for ethinylestradiol and one common plasticizer, though it found no unacceptable carcinogenic risk from estrogenic activity for any of the compounds evaluated.9PubMed. Estrogenic compounds in drinking water: A systematic review and risk analysis The concentrations in finished drinking water are generally extremely low, but the concern is chronic, lifelong exposure at those low levels, not a single glass of water.
What Conventional Sewage Treatment Accomplishes
Standard wastewater treatment plants were never designed to target hormones, yet they do remove a substantial share through biological processes that happen to break down some of these compounds. The catch is that performance varies enormously depending on operating conditions like how long the microbial sludge stays in the system and whether conditions favor aerobic or anaerobic bacteria.10PubMed. Treatment and removal strategies for estrogens from wastewater
A pilot-plant study put numbers on this unevenness. Testosterone, androstenedione, and progesterone were effectively eliminated, dropping to detection-limit concentrations. The natural estrogens fared reasonably well: estradiol was removed by about 99% and estrone by about 82%, for a combined natural-estrogen removal averaging 89%. But synthetic ethinylestradiol, the one found in oral contraceptives, proved far more stubborn, with an average removal of only about 42%.11PubMed. Fate of sex hormones in two pilot-scale municipal wastewater treatment plants: conventional treatment A full-scale plant study confirmed that while androgens hit removal rates of 98–99% and most other hormone classes ranged from roughly 73–99%, there was real variation across individual compounds and across different zones of the treatment process.12PubMed. Behaviors of glucocorticoids, androgens and progestogens in a municipal sewage treatment plant: comparison to estrogens
The practical takeaway is that conventional treatment does a lot of the heavy lifting for natural hormones but leaves a gap, especially for synthetic estrogens. That gap is what the advanced methods below are designed to close.
Activated Carbon Adsorption
Activated carbon works by trapping hormone molecules onto its enormous internal surface area. The more carbon you add, the more hormones it captures, and at sufficient doses, removal can be essentially complete for estrogens in controlled experiments. When ozone was used alongside activated carbon, removal was also complete, with ozone additionally lowering other organic contaminants.13PubMed. Removal of estrogens from water using activated carbon and ozone In full-scale water treatment, activated carbon is already widely used, either as granular beds that water flows through or as powder added directly to the treatment stream. Its effectiveness for hormone removal depends on the dose and contact time, the amount of competing organic matter in the water, and how often the carbon is regenerated or replaced. When competing compounds are present, as they always are in real wastewater, each hormone gets slightly less surface area to latch onto, which means removal rates drop compared to clean laboratory conditions.
Membrane Filtration
Reverse osmosis and nanofiltration membranes act as physical barriers, and their tighter versions can reject hormone molecules quite effectively. Tight nanofiltration and reverse osmosis membranes retained the natural hormone estrone well, though the mechanism is more complex than a simple sieve. Adsorption of the hormone onto the membrane surface plays a significant role alongside size exclusion, meaning that the membrane’s chemical properties matter as much as its pore size. Changes in water chemistry, like shifts in salt concentration or pH, can alter how well the membrane holds onto hormone molecules.14Environmental Science & Technology. Removal of the Natural Hormone Estrone from Aqueous Solutions Using Nanofiltration and Reverse Osmosis Looser, more porous nanofiltration membranes are less reliable; their retention depends heavily on maintaining adsorptive capacity at the membrane surface, and once that saturates, hormones break through.15Journal of Membrane Science. Estrogenic hormone removal from wastewater using NF/RO membranes
For municipal and industrial applications, reverse osmosis is one of the most effective single-step hormone removal technologies available, but it comes at a high energy and maintenance cost and produces a concentrated waste stream that still needs handling. Nanofiltration uses less energy but offers less consistent hormone rejection.
Ozone and Advanced Oxidation
Advanced oxidation processes use powerful reactive species, most often generated from ozone, hydrogen peroxide, ultraviolet light, or combinations of these, to chemically break apart hormone molecules. A comparative study of several advanced oxidation approaches found that all of them achieved high removal of estrone itself, and that ozonation came out as the most cost-effective option at roughly $0.34 per thousand gallons when both capital and operating costs were included. Ozone also outperformed UV-based methods at removing total organic carbon and reducing the overall estrogenic activity of the treated water.16PubMed. Degradation of estrone in water and wastewater by various advanced oxidation processes
UV-driven photocatalysis using titanium dioxide is another approach that has attracted research interest, particularly because it can be powered by sunlight. When titanium dioxide was used as a photocatalyst in a solar-powered reactor to treat tap water spiked with four estrogens, removal reached about 85% after three hours of treatment under optimized conditions.17Journal of Environmental Chemical Engineering. Degradation of hormones in tap water by heterogeneous solar TiO2-photocatalysis: Optimization, degradation products identification, and estrogenic activity removal Increasing the amount of titanium dioxide boosted the degradation rate, but only up to a point; too much caused light scattering that reduced effectiveness.18PubMed. Titanium dioxide mediated photocatalytic degradation of 17beta-estradiol in aqueous solution
The Byproduct Problem
Destroying the parent hormone molecule does not automatically make the water safe, and this is an underappreciated complication. When ozone or chlorine attacks a hormone, it breaks it into smaller fragments called transformation products. These fragments sometimes retain estrogenic activity, and in certain cases their toxicity is actually higher than the original compound. Researchers monitoring ozone treatment of bisphenol A observed that estrogenic activity initially increased before tapering off, likely because early breakdown products were more estrogenic than the starting material. A separate study of ethinylestradiol ozonation found that while the byproducts had lower estrogenic activity, they were more toxic overall.19The Open Biotechnology Journal. Removal of Endocrine Disruptors from Urban Wastewater by Advanced Oxidation Processes (AOPs): A Review
Chlorine treatment showed a similar pattern in a drinking water simulation study, where individual hormone concentrations dropped anywhere from less than 10% to over 90% depending on the compound, but the hormones were transformed into oxidation byproducts rather than truly eliminated.20PubMed. Fate of endocrine-disruptor, pharmaceutical, and personal care product chemicals during simulated drinking water treatment processes The solar photocatalysis study mentioned earlier ran into the same wall: even after nine hours of treatment, the estrogenic activity of the treated water was not completely eliminated, despite substantial removal of the target hormones themselves.17Journal of Environmental Chemical Engineering. Degradation of hormones in tap water by heterogeneous solar TiO2-photocatalysis: Optimization, degradation products identification, and estrogenic activity removal This is why measuring hormone concentration alone can be misleading. A treatment method that destroys 95% of estradiol has not necessarily eliminated 95% of the estrogenic risk.
Constructed Wetlands
Engineered wetlands offer a lower-tech, nature-based alternative. These systems use combinations of gravel beds, aquatic plants, and microbial communities to break down contaminants as water flows slowly through them. For steroid hormones, biodegradation by microbes is the dominant removal mechanism, with plant uptake and adsorption onto the substrate playing smaller supporting roles.21Journal of Environmental Chemical Engineering. A review on the occurrence, fate and removal of steroidal hormones during treatment with different types of constructed wetlands
Performance depends heavily on design. A study testing four different constructed wetland configurations found steroid hormone removal ranging from about 15% to 100% depending on the compound and the system. Adding artificial aeration and connecting multiple wetland stages in series significantly improved results. The best-performing setup paired two aerated stages in sequence and brought ecological risk from most of the detected hormones down to acceptable levels.22PubMed. Optimized constructed wetlands enhance the removal and reduce the risks of steroid hormones in domestic wastewater Aerobic conditions generally favor hormone breakdown, which is why vertical-flow wetlands, which naturally pull in more oxygen, tend to outperform horizontal-flow designs.21Journal of Environmental Chemical Engineering. A review on the occurrence, fate and removal of steroidal hormones during treatment with different types of constructed wetlands
A separate lab-scale study testing subsurface constructed wetlands planted with different species found that removal of ethinylestradiol ranged from about 9% to 96% depending on the design, while the progestin levonorgestrel reached up to 100% removal in the best-performing system.23PubMed. Removal of the endocrine disruptors ethinyl estradiol, bisphenol A, and levonorgestrel by subsurface constructed wetlands The enormous range underscores the point that a poorly designed wetland may accomplish very little, while an optimized one can rival more expensive technologies for certain hormones.
What You Can Do at Home
If you are on a municipal water supply, most of the hormone removal has already happened at the treatment plant before water reaches your tap. The concentrations remaining in finished drinking water are typically at the parts-per-trillion level, far below anything you could taste or smell. Still, people interested in an extra layer of protection do have options.
A home reverse osmosis system is the most effective household technology for rejecting hormone molecules, for the same reasons it works at the industrial scale. Countertop and under-sink RO units are widely available and relatively affordable, though they waste some water and remove beneficial minerals along with contaminants.
Activated carbon filters, the kind found in standard pitcher filters and faucet-mount units, can adsorb some hormone residues, but their effectiveness depends on carbon quality, flow rate, and how often you replace the cartridge. A saturated filter stops working. Granular activated carbon block filters generally outperform loose granular ones because they force water through more tightly packed carbon with longer contact time.
A more surprising finding involves household chlorine bleach. One study tested a simple slow sand filter paired with bleach addition at different chlorine concentrations. The sand filter alone removed less than 15% of the endocrine-disrupting compounds tested. But when chlorine was added to the filter effluent at concentrations above 5 milligrams per liter, removal exceeded 98% for all three compounds. Even at much lower chlorine doses of about 2 milligrams per liter, removal reached nearly 70%.24PubMed. Assessing an intermittently operated household scale slow sand filter paired with household bleach for the removal of endocrine disrupting compounds This approach is more relevant for people in developing regions using point-of-use water treatment than for someone on a treated municipal supply, but it demonstrates that even simple oxidation chemistry can make a real dent.
Biological and Enzymatic Approaches
One of the more promising frontiers involves using fungi and their enzymes to break down hormones. White-rot fungi produce an enzyme called laccase that efficiently oxidizes estrogens. Researchers have tested laccase from the fungus Trametes versicolor on both natural and synthetic estrogens in real municipal wastewater, finding it effective at catalyzing their breakdown.25PubMed. Laccase-catalyzed conversion of natural and synthetic hormones from a municipal wastewater A systematic review of fungal treatment for endocrine disruptors confirmed that laccase-based approaches show high efficiency and position fungal treatment as an environmentally friendly alternative to conventional chemical methods.26Water. Bioremediation of Endocrine Disruptors (EDs): A Systematic Review of Fungal Application in ED Removal from Wastewater
The appeal here is that enzymes work under mild conditions, do not require high energy inputs, and can be produced renewably. The challenge is keeping enzymes active and stable in the messy, variable environment of real wastewater over long periods. Immobilizing the enzymes on solid supports helps, and several research groups are working on making these systems durable enough for continuous operation. This technology is not yet mainstream at treatment plants, but it is further along than many emerging approaches.
Molecularly Imprinted Polymers
A more experimental class of materials takes a lock-and-key approach to hormone capture. Molecularly imprinted polymers are synthetic materials molded around a template molecule, in this case an estrogen, so that when the template is removed, the polymer retains cavities shaped exactly to recapture that same molecule from a water sample. Magnetic versions of these polymers allow the material to be scattered into a water sample and then retrieved with a magnet, making separation simple.27PubMed Central. Molecularly Imprinted Polymers and Magnetic Molecularly Imprinted Polymers for Selective Determination of Estrogens in Water by ESI-MS/FAPA-MS
Mesoporous versions of these polymers, engineered with tiny internal channels to maximize surface area, have achieved adsorption capacities in the hundreds of milligrams of hormone per gram of material for both estrone and estriol.28Colloids and Surfaces A: Physicochemical and Engineering Aspects. Mesoporous molecularly imprinted polymer for removal of hormones from aqueous medium A magnetic mesoporous version tested for estradiol and ethinylestradiol showed similarly strong adsorption performance at a neutral pH, with the imprinted material outperforming its non-imprinted control, confirming that the molecular shaping genuinely improves selectivity.29Journal of Molecular Structure. Experimental and theoretical studies of a magnetic mesoporous molecularly imprinted polymer for selective adsorption of estrogens from aqueous solutions These materials are still primarily in the lab-research phase, but they point toward a future where adsorbents could be custom-designed for whichever hormone contamination profile a particular water source presents.
Why No Single Method Is Enough
Every removal technology has a blind spot. Activated carbon adsorbs hormones well but eventually saturates and needs replacement or regeneration, and it does not destroy the captured molecules. Ozone and UV oxidation destroy hormones but generate transformation products that may carry their own risks. Membranes reject hormones physically but produce a concentrated waste stream. Constructed wetlands work cheaply and at scale but are sensitive to design details and climate. Biological methods are elegant but still maturing.
The most effective real-world approaches stack multiple barriers. A treatment train might use conventional activated sludge to handle the bulk of natural hormones, followed by ozonation or activated carbon polishing to catch the synthetic estrogens that slip through, and membrane filtration as a final safeguard for drinking water production. Each layer compensates for the weaknesses of the others. Increasingly, water utilities in Europe and parts of Asia are adding an advanced treatment step specifically to address micropollutants including hormones, though many facilities worldwide still rely on conventional treatment alone. For anyone concerned about hormones in their own tap water, a home reverse osmosis unit provides the strongest additional defense, paired with regular filter replacement to prevent saturation from undoing the benefit.