Filtering medicine residues from tap water: what really works?

Filtering Medicine Residues in Tap Water: What Really Works?

The RIVM has detected over 30 pharmaceutical substances in Dutch drinking water sources. Painkillers, hormones, antibiotics, antidepressants: they end up in wastewater via human excretion and pass through wastewater treatment plants that are not designed to remove them. Which filter effectively removes medicine residues in tap water? And what makes the PureFilter Mineral+ different from the rest?

What are medicine residues in tap water?

When people take medicines, the body does not absorb 100% of the active substance. The remainder leaves the body via urine and faeces, flows through the sewer to a wastewater treatment plant (WWTP), and partly ends up in rivers and lakes. Annually, an estimated minimum of 190,000 kilograms of medicine residues enter Dutch surface water through this system, according to the Dutch government.

WWTPs are designed for nutrients, organic matter, and bacteria, but not for the molecular size of pharmaceutical substances. The result: traces of medicines eventually reach tap water.

Which medicine residues are found in Dutch tap water?

The RIVM, together with drinking water companies, has detected over 30 pharmaceutical substances in Dutch drinking water sources. The most common groups are:

• Painkillers and anti-inflammatories: diclofenac, ibuprofen, and naproxen. Diclofenac is almost universally found in Dutch surface water.
• Hormones: ethinylestradiol (from the contraceptive pill), testosterone, and other steroids. Hormone-disrupting effects in fish have been demonstrated at concentrations as low as 1 nanogram per litre.
• Antibiotics: sulfamethoxazole, amoxicillin, and trimethoprim. The presence of antibiotics in water contributes to antibiotic resistance. The WHO has declared this one of the ten biggest threats to global health.
• Antidepressants and psychotropic drugs: carbamazepine, venlafaxine, and fluoxetine. Carbamazepine hardly degrades in the environment and serves as a marker substance for pharmaceutical contamination.
• Beta-blockers: metoprolol and atenolol, commonly used for cardiovascular diseases.
• Diabetes medication: metformin, the most prescribed diabetes medicine worldwide, found in high concentrations in surface water.
• X-ray contrast agents: iomeprol and iopromide are excreted in large quantities after hospital use and are chemically very stable.

Concentrations in purified tap water are generally in the order of nanograms per litre. For comparison: a standard aspirin tablet contains 500,000,000 nanograms of active ingredient. The detected values are millions of times lower than a therapeutic dose.

How dangerous are medicine residues for health?

The RIVM states that the concentrations in Dutch tap water are too low to cause direct health damage with normal consumption. Therefore, there are no legal limit values for medicine residues in drinking water. Dutch drinking water companies supply water that is well within all applicable standards.

That's the good news. At the same time, scientists add two caveats. Firstly, the long-term effects of daily exposure to a cocktail of dozens of substances simultaneously have been insufficiently studied. Secondly, certain groups may be particularly vulnerable:

• Pregnant women and foetuses (hormone-disrupting substances)
• Babies and young children (still developing hormonal system)
• People with impaired kidney or liver function
• People already taking medication (cumulative effect)

Environmental effects have been more clearly demonstrated. In English rivers, more than a third of male fish were found to have developed feminisation characteristics due to hormone disruption. Antibiotics in water encourage bacteria to develop resistance, which poses a growing global risk.

The cocktail effect: the unknown risks

Toxicology traditionally assesses substances individually: how dangerous is substance X at dose Y? In practice, the human body is daily exposed to a mixture of dozens of pharmaceutical substances simultaneously. This is called the cocktail effect or combination effect.

Scientific research shows that substances in combination can act synergistically: they enhance each other's effect, even if each individual is well below the safe threshold. The RIVM acknowledges that this is a blind spot in current policy: there are standards per substance, but no standards for combinations.

What does NOT work against medicine residues?

There are many misconceptions about methods that supposedly remove medicine residues but in reality do not, or hardly do:

• Boiling: medicine residues are heat-resistant above 100°C. Due to evaporation, the concentration in the remaining water actually increases.
• UV light: disinfects bacteria and viruses, but has no effect on chemical molecules. Medicine residues are not living organisms.
• Simple GAC filters (loose carbon granules): the contact time between water and carbon is too short for effective adsorption of pharmaceutical molecules. This applies to many cheap tap filters and filter jugs.
• Sediment filters: trap particles, but medicine residues are dissolved in the water. Compare it to straining sugar from tea.
• Water softeners: remove limescale (calcium and magnesium) but leave pharmaceutical substances completely untouched.
• Kettles and dispensers without filters: heat or cool water but filter nothing.

Which filter technology really works?

Three proven technologies effectively remove medicine residues from drinking water:

1. Pressed Activated Carbon Block (Carbon Block)

Activated carbon block is the most effective method for home use. The carbon is compressed into a solid block, guiding water through microscopic channels. One gram of activated carbon has an internal surface area of up to 3,000 m², larger than half a football field. Via adsorption, pharmaceutical molecules adhere to the carbon surface and remain in the filter.

The difference with loose carbon granules (GAC) is the contact time: with a pressed carbon block, it is much longer, significantly increasing removal efficiency. This is the technology PureFilter applies in the Mineral+.

2. Ceramic Filtration with Activated Carbon Core

Ceramic filters work by gravity. Water slowly seeps through a ceramic element (pore size 0.2 to 0.9 micrometres) with an activated carbon core. The low flow rate provides optimal contact time. Effective against bacteria, cysts, and pharmaceutical substances, but requires a freestanding system and offers less convenience than an inline filter.

3. Ion Exchange (5-stage)

Ion exchange removes almost all dissolved substances, including medicine residues, via synthetic resin beads that exchange ions. The TDS (total dissolved solids) drops to 0 ppm. Disadvantage: useful minerals like calcium and magnesium are also removed, and the filter quickly saturates with hard water.

How does PureFilter remove medicine residues AND add minerals?

The PureFilter Mineral+ combines two functions that other filters do not offer simultaneously: purification and mineralisation.

Most filters, such as ion exchange and reverse osmosis, remove not only contaminants but also beneficial minerals like calcium, magnesium, and potassium. PureFilter solves this with a two-step approach:

• Step 1: Filtration the pressed activated carbon block removes over 100 contaminants, including PFAS, microplastics, medicine residues, heavy metals, chlorine, fluoride, and nitrates. The filter is certified according to NSF 42, NSF 53, NSF 61, and NSF 372, the international gold standard for water filtration.
• Step 2: Mineralisation via Swedish Mineral Rock™ calcium, magnesium, and potassium are added to the filtered water. The result is clear, mineral-rich water without unwanted substances.

At PureFilter, we see that customers primarily choose the Mineral+ because they don't want to make compromises: pure and mineral-rich water, without plastic bottled water and without complicated installation.

Comparison: PureFilter vs. other filter options

Buying guide: which filter is right for you?

• Do you want to filter medicine residues, PFAS, and microplastics AND retain minerals? The PureFilter Mineral+ is the only option that combines all of this in one system, without removing minerals.
• Do you want maximum removal of all dissolved substances? Reverse osmosis removes the most, but also all minerals and requires a plumber for installation.
• Do you not need a water connection under the sink? A gravity filter like the Berkey works freestanding, but is larger, slower, and not Quooker-compatible.
• Are you looking for a temporary, cheap solution? A Brita filter tap is affordable but only partially filters medicine residues and quickly runs out of filter cartridges.

For most Dutch households who want extra assurance about medicine residues, PFAS, and microplastics, and also want to enjoy mineral water, the PureFilter Mineral+ is the most complete and cost-effective choice in the long term.

Frequently Asked Questions about Medicine Residues and Water Filters

Conclusion

Medicinal residues in tap water are a measurable reality in the Netherlands: the RIVM has found more than 30 pharmaceutical substances in drinking water sources. Concentrations are low and do not pose an acute health risk, but the long-term effects of the cocktail effect are unknown.

Not every filter works. Boiling, UV light, and simple tap filters fall short. What does work: a compressed activated carbon block with sufficient contact time. The PureFilter Mineral+ combines effective removal of over 100 contaminants, including medicinal residues, PFAS, and microplastics, with the unique advantage of adding calcium, magnesium, and potassium via Swedish Mineral Rock™. It's the only filter that filters and mineralizes.

With a capacity of 15,000 to 20,000 liters per filter cartridge, an installation time of 5 to 10 minutes, and a price of €149.90, the PureFilter Mineral+ is the most complete and cost-efficient choice for Dutch tap water. View the full product page on purefilter.nl or read more about the best water filters for your situation.