When talking about drinking water quality, treatment technologies and limit values are usually at the forefront. A crucial factor often goes unnoticed: the age of the pipes through which the water is transported. In many cities, these pipes are several decades old – with direct effects on water quality.
Water does not remain unchanged after treatment. The pipe network becomes part of the contamination chain.
Old Infrastructure is the Norm
Large parts of the drinking water networks in Europe were built in the last century. Many pipelines are significantly older than their originally planned service life. Even if they are still hydraulically functional, their material and chemical properties change over time.
These changes occur gradually and usually remain invisible.
Corrosion and Material Aging
With increasing age, the inner surfaces of pipelines change. Metallic pipes form corrosion layers, coatings lose their protective effect, and plastics age. This changes the interaction between water and pipe material.
Corrosion can release metals such as iron, copper, or lead. Material degradation can lead to increased particle load or altered chemical reactions in the water.
Biofilms in the Pipe Network
Aging pipelines promote the formation of biofilms. These microbial structures adhere to the inner walls of the pipes and are normal even in treated water systems. However, biofilms change the chemical dynamics of the water.
They can degrade disinfectants, release metabolic products, and, with changes in flow, release material into the water, leading to fluctuating quality at the tap.
Why Flushing Alone Is Not Enough
Water suppliers regularly flush pipe networks and adapt the treatment. These measures are important, but can only limit the effects of aging infrastructure. Flushing can temporarily dislodge deposits and thus cause temporary peak loads.
Centralized treatment does not have complete access to the interior of old pipes.
The Relevant Contamination Occurs at the Tap
From a health perspective, what actually comes out of the tap is crucial. Aging pipes influence precisely this last section. Even with standard-compliant treatment, distribution-related changes can determine the final water quality.
Pipe age is therefore a silent but central risk factor.
Why the Focus on the Household is Crucial
Drinking water quality cannot be assessed solely at the source. The conditions in the pipe network and in the building play a significant role. A household-level view considers the water as it is actually used.
Drinking water safety does not end at the waterworks.
It arises – or changes – on the way there.
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