The presence of pharmaceutical compounds in water bodies has become one of the most significant environmental concerns of the past two decades. Traces of analgesics, antibiotics, hormones, psychiatric drugs and other active pharmaceutical ingredients are being detected in rivers, groundwater and even treated drinking water supplies across the globe, raising serious questions about long-term impacts on ecosystems and human health.
Our work in water quality assessment and treatment has given us first-hand insight into the growing challenge posed by these emerging contaminants. This article examines the sources, pathways and risks associated with pharmaceutical contamination in water, along with the technologies currently available to address it.
How Do Pharmaceuticals End Up in Water?
Pharmaceutical compounds enter the water cycle through multiple pathways, most of which are linked to everyday human activity and industrial processes:
Human excretion and domestic wastewater
The primary source of pharmaceutical contamination in water is human metabolism. After ingesting a medicine, the body absorbs and metabolises only a fraction of the active ingredient. The remainder is excreted, either as the parent compound or as metabolites, through urine and faeces. These substances enter the sewage system and reach wastewater treatment plants (WWTPs), which were not originally designed to remove pharmaceutical micro-pollutants.
Improper disposal of unused medicines
Flushing expired or surplus medicines down the toilet or discarding them in household waste constitutes a direct, avoidable route of contamination. Despite public awareness campaigns and pharmacy take-back schemes in many countries, improper disposal remains a widespread practice that contributes measurably to pharmaceutical loads in wastewater.
Hospital and healthcare facility effluents
Hospitals and care facilities generate wastewater with particularly high concentrations of pharmaceuticals, including antibiotics, contrast agents, anaesthetics and cytotoxic drugs. In many jurisdictions, hospital effluent is discharged directly into the municipal sewer network without pre-treatment, adding to the burden on downstream WWTPs.
Agricultural and veterinary use
The use of veterinary pharmaceuticals —particularly antibiotics, antiparasitics and growth promoters— in livestock farming results in the release of these compounds into the environment through animal manure applied to agricultural land. From there, they can leach into groundwater or be carried by surface runoff into rivers and reservoirs. Aquaculture operations represent an additional source, as drugs administered to farmed fish dissolve directly into the surrounding water.
Pharmaceutical manufacturing
Although manufacturing discharges are typically regulated, industrial effluents from pharmaceutical production facilities can contain elevated concentrations of active ingredients. This issue is particularly acute in regions with less stringent environmental oversight, where production wastewater may receive insufficient treatment before discharge.
Which Pharmaceutical Compounds Are Most Frequently Detected?
Environmental monitoring programmes across Europe and North America consistently identify several categories of pharmaceuticals in surface water and groundwater:
- Non-steroidal anti-inflammatory drugs (NSAIDs): ibuprofen, diclofenac and naproxen are among the most ubiquitous pharmaceutical contaminants in European rivers, owing to their high consumption rates and incomplete removal in WWTPs.
- Antibiotics: compounds such as amoxicillin, ciprofloxacin, sulfamethoxazole and erythromycin are detected with increasing frequency. Their presence in the environment is of particular concern due to its contribution to antimicrobial resistance (AMR), which the WHO has identified as one of the top ten global public health threats.
- Hormones and endocrine disruptors: synthetic oestrogens from oral contraceptives (notably ethinylestradiol) and natural hormones excreted by humans and livestock are found at biologically active concentrations in many water bodies, causing feminisation of fish and disruption of reproductive processes in aquatic organisms.
- Psychiatric and neurological drugs: antidepressants (fluoxetine, venlafaxine), anxiolytics (diazepam) and antiepileptics (carbamazepine) are highly persistent in the aquatic environment. Carbamazepine, due to its resistance to biodegradation, is often used as a marker compound for anthropogenic contamination of water sources.
- Cardiovascular drugs: beta-blockers (atenolol, metoprolol) and lipid regulators (bezafibrate, gemfibrozil) are routinely detected in WWTP effluents and downstream water courses.
Health Risks of Pharmaceuticals in Drinking Water
The concentrations of individual pharmaceutical compounds typically found in treated drinking water are extremely low, generally in the range of nanograms to low micrograms per litre —orders of magnitude below therapeutic doses. However, several aspects of this exposure warrant serious attention:
Chronic low-dose exposure
Unlike therapeutic use, exposure to pharmaceuticals through drinking water is involuntary, continuous and lifelong. The long-term health effects of sustained exposure to trace levels of dozens of active compounds simultaneously are still poorly understood. Conventional toxicological risk assessment, based on individual substances and short-term exposure, may not adequately capture the cumulative risk.
Mixture effects
Drinking water consumers are not exposed to a single pharmaceutical but to a complex cocktail of compounds that may interact in ways that are difficult to predict. Additive, synergistic or antagonistic effects between different substances are an active area of research, with early evidence suggesting that mixtures may exert biological effects at concentrations where individual compounds would not.
Vulnerable populations
Infants, pregnant women, the elderly and immunocompromised individuals may be disproportionately affected by pharmaceutical residues in water. Developing organisms are particularly sensitive to endocrine-disrupting compounds, even at very low concentrations.
Antimicrobial resistance
The continuous release of sub-therapeutic concentrations of antibiotics into the environment exerts selective pressure on microbial communities, promoting the development and spread of antibiotic-resistant bacteria. Water bodies receiving WWTP effluent have been identified as hotspots for the horizontal transfer of resistance genes, with implications that extend far beyond the aquatic environment.
Regulatory Framework: the EU Approach
The European Union has progressively strengthened its regulatory response to pharmaceutical contamination in water:
- The EU Water Framework Directive (2000/60/EC) established the principle of monitoring and controlling priority substances in surface water, including certain pharmaceutical compounds.
- Directive 2013/39/EU added diclofenac, 17-alpha-ethinylestradiol and 17-beta-estradiol to the Watch List of substances requiring EU-wide monitoring.
- The revised Drinking Water Directive (2020/2184) introduced, for the first time, provisions for monitoring micro-pollutants —including pharmaceuticals— in drinking water sources and supplies. It also established parametric values for PFAS compounds, signalling a broader shift towards regulating emerging contaminants.
- The proposal for a revised Urban Wastewater Treatment Directive (2022) includes requirements for advanced treatment (quaternary treatment) at larger WWTPs to remove micro-pollutants, under the Extended Producer Responsibility principle, whereby the pharmaceutical and cosmetics industries would contribute to the costs of upgrading treatment infrastructure.
In Spain, the transposition of the Drinking Water Directive through the Real Decreto on drinking water quality has introduced new monitoring requirements for emerging contaminants, including certain pharmaceutical compounds.
Treatment Technologies for Removing Pharmaceuticals from Water
Conventional wastewater treatment processes (primary sedimentation and secondary biological treatment) achieve variable and often incomplete removal of pharmaceutical compounds. While some substances are partially biodegraded or adsorbed onto sludge, many persist in the treated effluent. Effective removal requires the application of advanced treatment technologies:
Ozonation
The injection of ozone (O₃) into water produces highly reactive oxidant species that break down the molecular structure of pharmaceutical compounds. Ozonation is one of the most effective and widely implemented advanced treatment methods, achieving removal rates above 90 % for most pharmaceuticals. Its main limitation is the potential formation of transformation products whose toxicity must be assessed, and the energy cost of ozone generation.
Activated carbon adsorption
Granular activated carbon (GAC) filters and powdered activated carbon (PAC) dosing are effective at removing a broad spectrum of pharmaceutical compounds through adsorption. These technologies are well established in drinking water treatment and can be integrated into existing infrastructure with relative ease. The main considerations are carbon regeneration or replacement costs and the management of spent carbon.
Advanced oxidation processes (AOPs)
Processes combining UV radiation with hydrogen peroxide (UV/H₂O₂) or other oxidants generate hydroxyl radicals with extremely high reactivity towards organic micro-pollutants. AOPs are particularly useful for degrading persistent compounds that resist conventional treatment and ozonation. Their energy requirements are higher, and they are typically applied as a polishing step.
Membrane filtration
Nanofiltration (NF) and reverse osmosis (RO) membranes provide a physical barrier capable of rejecting pharmaceutical molecules based on size exclusion and charge repulsion. These technologies achieve very high removal rates but generate a concentrated reject stream that requires management, and their energy consumption is significant.
Nature-based and hybrid solutions
Constructed wetlands, managed aquifer recharge systems and soil-aquifer treatment can achieve partial removal of pharmaceutical compounds through a combination of biodegradation, adsorption and photodegradation. While less effective as standalone solutions, they offer a low-energy complement to engineered treatment systems, particularly in rural or decentralised contexts.
Litoclean’s Approach to Pharmaceutical Contamination in Water
We address the challenge of pharmaceutical contamination in water through a combination of analytical expertise, regulatory knowledge and practical project experience:
- Assessment and monitoring of emerging contaminants, including pharmaceuticals, in surface water, groundwater and drinking water supplies.
- Evaluation of treatment performance and identification of upgrade options for WWTPs facing new regulatory requirements.
- Research and innovation through our Innovation Centre (CIL), where we develop and test advanced treatment solutions adapted to specific water quality challenges.
- Technical advisory services to water utilities, industrial operators and public authorities navigating the evolving regulatory landscape for emerging contaminants.
The presence of pharmaceuticals in water is a challenge that requires the combined efforts of regulators, water utilities, healthcare systems and environmental specialists. If your organisation needs support in assessing or managing pharmaceutical contamination in water, contact our team.
Frequently Asked Questions
How do pharmaceuticals get into drinking water?
Pharmaceuticals enter drinking water primarily through human excretion after medication use. The compounds pass through wastewater treatment plants, which were not designed to remove them completely, and reach rivers and aquifers that serve as drinking water sources. Improper disposal of medicines and agricultural runoff are additional pathways.
Are pharmaceuticals in drinking water dangerous?
The concentrations found in treated drinking water are far below therapeutic doses. However, the long-term effects of continuous exposure to complex mixtures of pharmaceutical residues are not yet fully understood. Vulnerable populations such as infants and pregnant women may face higher relative risk. The contribution to antimicrobial resistance is a separate and well-documented concern.
Can water filters remove pharmaceuticals?
Standard domestic water filters (jug filters, basic carbon filters) provide limited removal of pharmaceutical compounds. More advanced systems using activated carbon blocks, reverse osmosis or a combination of both can achieve significantly higher removal rates. However, the most effective approach is treatment at the source, through advanced technologies applied at water treatment plants.
What does the EU require regarding pharmaceuticals in water?
The revised EU Drinking Water Directive (2020/2184) introduced monitoring requirements for micro-pollutants including certain pharmaceuticals. The proposed revision of the Urban Wastewater Treatment Directive includes requirements for advanced (quaternary) treatment at larger plants. Member states are at different stages of transposing these requirements into national legislation.
What treatment technologies are most effective?
Ozonation and activated carbon adsorption are currently the most widely adopted and effective technologies for removing pharmaceuticals from water. Advanced oxidation processes and membrane filtration (nanofiltration, reverse osmosis) provide additional options for specific applications. The optimal solution depends on the water matrix, target compounds and operational context.
