What can happen between the waterworks and the glass of water

The journey of water to your tap

German tap water is considered to be among the best regulated in the world. The Drinking Water Ordinance (TrinkwV), most recently comprehensively amended in June 2023, sets strict limits for over 50 parameters. Our waterworks do an excellent job. That’s the good news.

The lesser-known side: the waterworks’ control ends at the property connection. What happens on its way through your home’s pipes lies outside the utility companies’ remit – and is the responsibility of the property owners. And there are substances that even the most modern waterworks cannot remove completely.

What might be found in tap water?

Nitrate: In agricultural areas, nitrate enters the groundwater through fertilisation. The limit is 50 mg/l and has remained unchanged since the last amendment. Elevated levels are regularly measured, particularly in rural regions with intensive agriculture. In the body, nitrate can be converted into nitrite and potentially into carcinogenic nitrosamines – a risk that is particularly relevant for infants and pregnant women.

PFAS – the ‘forever chemicals’: Per- and polyfluoroalkyl substances have only been regulated at all since the 2023 amendment to the Drinking Water Ordinance. From January 2026, a total limit of 0.1 µg/l will apply to 20 PFAS substances relevant to drinking water. From 2028, the limits for four particularly critical compounds (PFOA, PFOS, PFHxS, PFNA) will be tightened to 0.02 µg/l. PFAS are extremely persistent – they practically do not degrade in the environment and accumulate in the human body.

Heavy metals: Lead, copper and nickel can leach from older pipes and fittings – particularly when water stands in the pipes for long periods, such as overnight or whilst on holiday. The Drinking Water Ordinance stipulates that all lead pipes must be replaced or decommissioned by January 2026. The limit value for lead will be reduced from 10 µg/l to 5 µg/l in 2028. Nevertheless, lead pipes are still installed in many older buildings.

Medication residues: Antibiotics, hormones, painkillers, blood pressure-lowering drugs – traces of these enter the water cycle via wastewater. Sewage treatment plants cannot completely eliminate these substances. To date, there are no limit values for most medication residues in the Drinking Water Ordinance.

Microplastics: A study found plastic particles in 72% of German tap water samples. A study by the Technical University of Berlin detected microplastics in almost all samples of Berlin tap water examined, with concentrations ranging from 0.3 to 9.2 particles per litre. Currently, there is no limit value for microplastics in the German Drinking Water Ordinance. Of particular concern: studies from 2024 show that microplastic particles smaller than 0.2 micrometres can cross the blood-brain barrier. In a further study, microplastics were found in all placenta samples examined.

Chlorine and disinfection by-products: In some regions, chlorine is used for disinfection. This can result in the formation of so-called trihalomethanes (THMs), compounds considered to be potentially carcinogenic. Chlorine also affects the taste and smell of the water, something many people find unpleasant, even if the quantities may be harmless to health.

Limescale (calcium and magnesium compounds): Limescale in water is not generally harmful to health; on the contrary, calcium and magnesium are important minerals. However, very hard water can affect the taste, cause appliances to become encrusted with limescale and make skin care more difficult. Water hardness varies greatly in Germany depending on the region and groundwater source.

Origin makes the difference

Water is not the same everywhere in Germany. In regions where raw water is extracted from deep groundwater layers, contamination levels are generally lower than in areas where surface water from lakes and rivers is treated. Areas with intensive agriculture are more likely to have problems with nitrates and pesticides. Urban areas with older buildings tend to struggle with heavy metals from outdated pipes. And near industrial sites or military bases, PFAS contamination can be particularly high.

The issue of limit values

Limit values are an important tool, but they have their limitations. A limit value does not mean that a substance is harmless. It means that a certain quantity is considered tolerable. What is within acceptable limits for individual substances may have a different effect when combined with many other substances. This is because interactions between different substances – the so-called cocktail effect – are not taken into account in the limit values.

Furthermore, limit values are regularly tightened as new findings emerge. What is considered safe today may be assessed differently tomorrow. The reduction of the arsenic limit value from 10 to 4 µg/l (effective from 2036) or the introduction of PFAS limit values demonstrate that science is constantly learning.

The issue of bottled water

Some people turn to bottled water out of concern for tap water. But there are concerns here too. A widely cited study by Columbia University from 2024 found an average of around 240,000 nanoplastic particles per litre in bottled water, significantly more than in tap water. These originate primarily from the PET bottles themselves and are so small that they can penetrate cells and tissue. Added to this is the environmental footprint: transport, packaging and disposal make bottled water one of the most environmentally damaging forms of water supply.

What you can do

A good water filter removes contaminants where they last enter the system – right in your own home. This closes the gap between the waterworks and your glass of water. And you are not dependent on whether your home’s pipes are up to date or whether a landlord is fulfilling their obligations to replace them.

It is important to understand that a water filter is not a vote of no confidence in the waterworks. It is a sensible addition, the final step on the path to truly good water. Because the waterworks ensure that your water is safe. A good filter ensures that it is also good.

If you would like to know exactly how MAUNAWAI Pi technology works and which substances it specifically removes, read on in the ‘Our Technology’ section.