Hygiene and material safety of pipes for drinking water: what you need to know
Hygiene and material safety of drinking water pipes: what you need to know
When I talk to customers about water distribution in a house or apartment, most of them focus primarily on price, pipe diameter and the method of installation. Few raise the issue of hygiene and material safety – and yet it is a topic that directly affects the health of every member of the household every day. The water you drink, cook with, and use to brush your teeth – that water passes through your pipes. What can pass from them into it? Which materials are safe? What do the certificates mentioned by manufacturers on their products mean? And why should you pay attention not only to the price per meter but also to the overall material quality? This article answers all these questions with the professional depth the topic requires.
Why the material of the drinking water pipe is so important
Drinking water is not a chemically inert substance – it reacts with the materials it comes into contact with. Although most modern pipe materials have undergone long-term development towards hygienic safety, not all materials are equal and not every product on the market meets the same standards. Contamination of drinking water from within the pipe can take several forms:
- Migration of chemical substances – monomers, stabilizers, plasticizers or other additives used in the production of plastic materials can migrate into the water
- Release of metals – copper, zinc, lead or other metals from metal distribution systems or joints can dissolve into the water, especially at low pH values or higher temperatures
- Biological growth – some materials provide better nutrient conditions for bacteria, biofilm or legionella than others
- Odor and taste – even if the concentrations of migrating substances do not exceed hygienic limits, they can affect the sensory properties of water
This is precisely why there are strict regulatory frameworks in Europe and in Slovakia that determine which materials are allowed to come into contact with drinking water and what they must meet to obtain the appropriate certificates.
Legislative framework and certification: what materials for drinking water must meet
In Slovakia, the issue of hygienic safety of materials for drinking water is enshrined in several key regulations. Act No. 355/2007 Coll. on the protection, promotion and development of public health and Government Regulation No. 247/2017 Coll. of the Ministry of Health of the Slovak Republic on requirements for drinking water set limit values for substances that may be present in drinking water. In addition, manufacturers of pipe materials must comply with European standards and in many cases also national technical approvals.
At the European level, the key directive is Directive 98/83/EC on the quality of water intended for human consumption, which has been revised by the new EU Directive 2020/2184, implemented since 2023. This new directive introduced the so-called European list of approved materials for products in contact with drinking water – representing a significant step towards harmonizing requirements across the entire EU.
EN standards and technical approvals
Different standards apply to specific materials. Plastics for drinking water must meet the requirements of the EN ISO 15874 (PP), EN ISO 15875 (PEX), EN ISO 15877 (CPVC) or EN ISO 21003 (multi-layer pipes) series, with each material having to undergo migration testing. For copper, EN 1057 applies, including requirements for the content of corrosive and other harmful substances.
In France, Germany, the Netherlands and the United Kingdom, there are long-standing national approval systems (WRAS, DVGW, ACS, KiWa), which are often stricter in practice than the minimum European standard. Products bearing these certificates are generally a guarantee of high hygienic quality – and it is precisely these that you should ask for when choosing a piping system.
Overview of main materials and their hygienic profile
Multi-layer pipes (PEX-Al-PEX, PE-RT-Al-PE-RT)
Multi-layer pipes are probably the most widespread solution for domestic drinking water distribution today. Their basis is an inner layer of cross-linked polyethylene (PEX) or polyethylene with increased thermal resistance (PE-RT), a middle layer of aluminum and an outer protective plastic layer. From a hygienic point of view, the inner layer that comes into direct contact with the water is decisive.
PEX (cross-linked polyethylene) is a chemically very stable material. Unlike non-cross-linked plastics, monomers of polyethylene do not migrate from it, because the macromolecular structure is firmly bound. Studies carried out within the WRAS and DVGW approval processes confirm that properly manufactured PEX pipes have minimal migration of organic substances and do not cause changes in taste or odor of water. The aluminum layer also serves as an oxygen barrier, which is important when combined with heating systems, but from a hygienic point of view it mainly prevents degradation of polyethylene due to UV radiation and oxidation.
An example of proven products in this category is multi-layer pipe IVAR Turatec 16×2 mm or its larger variant, multi-layer pipe IVAR Turatec 20×2 mm, which are dimensioned for operating conditions PN10 at temperatures up to +70 °C or +95 °C. These parameters are directly related to hygienic safety, as higher temperatures accelerate potential substance migration – and certification includes testing at maximum operating temperatures.
Copper pipes
Copper is a historically proven material in the field of plumbing with demonstrated reliability. From a hygiene perspective, copper has an interesting dual nature: on one hand, it has natural antimicrobial properties (Cu²⁺ ions inhibit the growth of bacteria including Legionella pneumophila), on the other hand, it can be released into water under certain conditions in concentrations that may be problematic.
The EN 1057 standard for copper pipes defines a maximum lead content in the medium below 0.1 % – which is important because older brass fittings and soldered joints contained lead in much higher concentrations. Modern copper systems for drinking water use lead-free solder (Sn-Ag or Sn-Cu) and fittings certified for drinking water.
For drinking water distribution, it is important to monitor the pH value of the water: acidic water (pH below 7.0) significantly accelerates copper corrosion and the release of Cu²⁺ ions. The WHO limit for copper in drinking water is 2 mg/l, the Slovak decree copies the European limit of 2.0 mg/l. With neutral to slightly alkaline pH (7.0–8.5) and continuous use of the system, these limits are not exceeded in practice by copper pipes. Problems arise with long-term water stagnation and aggressive water with low pH or high CO₂ content.
Copper pipe HEPWORTH 15 mm and HEPWORTH 22 mm are classic solutions for apartment and single-family house installations, where copper demonstrates its value especially in sanitary applications with excellent resistance to high temperatures and mechanical influences. When properly installed (lead-free solder, certified fittings), it is a hygienically safe solution.
PPR and other plastic pipes
Polypropylene (PPR) is another widely used material. Certified PPR pipes for drinking water have relatively low migration, but compared to PEX, they are often less stable at higher temperatures in terms of long-term release of organic compounds. An important variable is the quality of the raw material and the presence of stabilizers, antioxidants and other additives, whose migration potential depends on the specific plastic formulation.
In no case should pipes without certification for contact with drinking water be used for drinking water distribution, for example, plastic pipes intended for technical water, irrigation systems or sewage. This mistake occasionally occurs in DIY renovations, when the type of pipe is confused based on visual similarity.
When and where is the real risk? Practical scenarios from practice
Over the years of work in the field of sales and advisory for piping systems, several situations have emerged where hygiene risks are not just theoretical, but real and measurable, manifesting in specific problems.
Scenario 1: Old installation with galvanized pipes
Galvanized steel pipes were the standard in apartment buildings constructed before 1990. The internal zinc coating gradually corrodes – first a protective corrosion layer forms, but after 20–30 years it starts to flake off and clog. In practice, this looks like water from the tap in the morning having a yellow-brown color and a metallic smell. These are corrosion products mixed with water. In such an installation, there may also still be lead-containing solder from the original installation. Reconstructing a galvanized installation is a hygiene necessity, not just an aesthetic matter.
Scenario 2: Low-quality plastic pipe without certification
It sometimes happens that during a bathroom renovation, where the customer or builder orders materials based on the lowest price, the piping ends up being non-certified for drinking water. It looks visually identical to certified products. After a few months, the customer reports that the water smells like "plastic" after prolonged stagnation (for example, after a vacation). Analysis may reveal elevated levels of organic compounds. The solution is always the same: replacement of the entire piping system.
Scenario 3: New installation with multilayer piping, but unsuitable fittings
This is a tricky scenario that occurs quite often in practice. The pipe is of high quality and certified – for example, multilayer pipe IVAR Turatec 18×2 mm – but the installer uses cheap fittings from an unknown source that do not meet hygiene requirements. Rubber seals in the fittings are a particular risk area: cheap seals made from recycled rubber may contain aromatics and other compounds that migrate into the water and cause a characteristic rubbery smell. Always require that the fittings come from the same manufacturer as the pipe and have NSF 61 or WRAS/DVGW certification.
Scenario 4: Legionella in an insufficiently circulated system
The bacterium Legionella pneumophila is dangerous precisely because it multiplies optimally in warm water at temperatures of 25–45 °C and in stagnant water. In a single-family home where hot water is heated to 55–60 °C and the system is sufficiently dimensioned with regular circulation, the risk is minimal. Problems arise in buildings with long branches without circulation, where the temperature drops into the critical range, or in recreational buildings that are closed for long periods. Here, the risk is not directly related to the pipe material, but to the system design – and that is why every hot water system should include a circulation branch and thermostatic valves maintaining a minimum temperature of 55 °C.
What to check when selecting piping from a hygiene perspective
When selecting piping for drinking water, you should systematically verify the following points:
- Certificate for contact with drinking water – the manufacturer must be able to provide a certificate from an accredited laboratory authority (WRAS, DVGW, ACS, KiWa, or Slovak RÚVZ). The marking on the pipe or in the technical documentation is sufficient.
- Material composition and standard – for PEX, you need to know which crosslinking degree it is (PEX-a, PEX-b, PEX-c) and whether the material meets EN ISO 15875. A higher crosslinking degree (over 70 %) means less migration.
- Temperature and pressure – the certification should cover real operating conditions, not just nominal laboratory conditions.
- Fittings and seals – it is essential that the accessories also meet hygiene standards. Rubber seals must be certified according to EN 681-1 or EN 549 for drinking water.
- Storage and handling – piping for drinking water must be protected from contamination during transport and on the construction site. A pipe that has been contaminated by oils from machines or other liquids is not suitable for drinking water.
- Flushing before commissioning – even if the piping is certified, it is necessary to flush the entire system with sufficient water before first use to remove any residues from production, cutting, or handling.
Hygienic safety during and after installation
Even if you have the highest quality certified piping in your hands, incorrect installation can significantly reduce the hygiene safety of the system. This is an area that customers underestimate even more than material selection.
Cleanliness during installation
Pipe ends should be protected against contamination with dirt throughout the entire installation process. On construction sites, dust from plaster, wood shavings, and floor sanding dust can get into open pipes. All of this can microbiologically contaminate the inner surface. Serious installers use pipe caps or adhesive film to cover open ends during work breaks.
Lubricants, seals and threaded connections
If threaded connections are used with Teflon tape or hemp, it is important to ensure that these materials are approved for potable water. Teflon tapes (PTFE) are generally inert and safe. Problems can arise when using various secondary sealing pastes – some contain antimicrobial biocides or organic solvents that are not approved for potable water. Always read what is written on the label.
Disinfection after installation
During extensive reconstruction or new construction, it is recommended to disinfect the entire pipe system before putting it into operation. The most common procedure is to flush the system with chlorinated water at a concentration of 10–50 mg/l free chlorine for at least 30 minutes, followed by a thorough rinse with clean water. This procedure is standard practice for installations in apartment buildings, hotels and healthcare facilities – it is carried out less systematically in single-family homes, but is equally justified.
First start-up and flushing
Even without formal disinfection, each new system should be thoroughly flushed before the first filling. Recommended procedure: open each outlet individually and let at least 5 minutes of water flow at full flow. Start with the outlets closest to the inlet pipe and proceed towards the more distant points. This ensures that the entire volume of water inside the pipe is replaced and any residues from production or installation are removed.
Water stagnation: an underestimated threat in new and old installations
One of the less discussed, but actually important hygiene factors is water stagnation in pipes. Stagnant water – that is, water that remains in the pipe without flow – is problematic from a hygiene point of view for several reasons:
- Increased microbial activity occurs in cold water at temperatures above 20 °C
- Legionella can multiply in warm water at temperatures below 55 °C
- Residual disinfection (chlorine) is depleted after several hours of stagnation, reducing water protection
- More organic substances are released from plastic pipes during stagnation than during flow, because the contact time of water with the material is longer
This means: if you have been on vacation for two weeks, the water in the pipes in your apartment is hygienically questionable upon your return – it is not dangerous in terms of acute poisoning, but it is not in the same condition as fresh water from the water supply network. Therefore, the standard recommendation is to let all outlets run for at least 2–3 minutes before drinking water after a longer absence.
When designing the piping system, it is therefore advisable to minimize dead legs – pipe sections where water remains stagnant for a long time. Each branch should be as short as possible and, ideally, the system should be designed as a loop system with circulation for hot water. This issue is discussed in more detail in the article Dimensioning pipes for potable water: how to calculate diameter and length in our Knowledge Center.
Material compatibility: what should not be mixed
In practice, we often encounter situations where it is necessary to connect different materials – for example, during partial reconstruction, where a new multi-layer system is connected to an old copper system. In such cases, several things should be taken into account.
Galvanic corrosion is a problem when two different metals are directly connected in the presence of water. Copper and galvanized steel form a galvanic cell, where zinc dissolves much faster. Therefore, it is not recommended to directly connect copper pipe to galvanized steel – a dielectric transition (plastic, special fittings) must be placed between them. Multi-layer pipe is neutral in this respect – PEX plastic does not cause galvanic corrosion, so the transition from copper to multi-layer is safe with standard direct fittings.
Another aspect is chemical compatibility: some plastic materials are sensitive to certain chemicals. For example, chlorinated water with high concentration can degrade certain types of PEX under certain conditions – this is why disinfection instructions for pipes before putting them into operation are so important and should be followed precisely according to the manufacturer's recommendations, not arbitrarily.
A more detailed comparison of both main types of pipes in this category can be found in the article Multi-layer pipe vs. HEPWORTH: which is better for your system.
Water quality control in the home piping system: when and how to test
For a household connected to the public water supply, it is not mandatory to test water quality at the point of use. The responsibility for water quality at the point of entry into the house lies with the public water supply operator. However, the responsibility for water quality after the meter (i.e. in the internal piping system) lies with the building owner – and if the water seems suspicious to you (smell, color, taste), it is appropriate to have it tested.
Accredited laboratories perform potable water analysis for basic quality indicators (pH, hardness, nitrate content, coliform bacteria, Escherichia coli, heavy metals including lead and copper) at a cost usually ranging from 40–100 € depending on the scope of the analysis. Water sampling is carried out from the tap after a 2–3 minute flushing flow, or from the first morning draw when testing for stagnation. If you have recently renovated the installation and want to confirm that everything is in order, such testing is a reasonable investment.
Signs that indicate a potential problem with the piping system are: yellowish or brownish water color (corrosion), metallic taste (heavy metals), plastic or rubber smell (unsuitable material or stagnation), cloudy water after longer stagnation (microbiological activity or corrosive products).
Final recommendations for practice
From everything we have covered, several specific practical recommendations emerge that should be kept in mind when making any decision about a piping system for potable water:
- Always buy pipe with verifiable certification for contact with potable water – WRAS, DVGW, ACS or equivalent national certification
- Do not combine certified pipe with low-quality fittings – fittings and seals are as important as the pipe itself
- With old installations with galvanized pipes, consider a comprehensive renovation rather than just patching
- Design the piping system to minimize dead legs and maximize flow – for hygiene reasons as well as hydraulic ones
- Always thoroughly flush the entire system before putting a new system into operation
- Always flush the water before drinking after a longer absence
- If you have doubts, have a water laboratory analysis done
Most frequently asked questions (FAQ)
Is multi-layer pipe safe for potable water? Migration from plastic?
Yes, quality multi-layer pipes with certification for potable water (WRAS, DVGW and others) are hygienically safe. The PEX material in the inner layer is chemically stable – due to the cross-linked structure of macromolecules, migration of organic compounds is very low and is well below the applicable hygiene limits. Problems could arise with low-quality products without certification or with pipes intended for technical applications – therefore, verification of certification is essential.
Is copper dangerous for health or not?
Copper in trace amounts is actually essential for the human body. The problem would be excessive intake – the valid limit for potable water is 2.0 mg/l. A properly installed copper pipe does not exceed this limit under normal conditions when the water has a neutral to slightly alkaline pH. The risk increases with aggressive (acidic) water, long stagnation and old solder joints containing lead. Modern lead-free solder and certified fittings eliminate this problem.
How can I tell if my pipe is not suitable for drinking water?
The pipe should have the marking "drinking water" or the appropriate certification symbol embossed on it. In the product's technical documentation, look for a mention of WRAS, DVGW, ACS certification or the EN ISO standard for plastic pipes for drinking water. If there is no such marking on the pipe or the manufacturer cannot provide proof, do not use the pipe for drinking water. A practical sign of a problem during operation is an unusual smell or taste of the water – this should always lead to further investigation.
Do I need to disinfect a new pipe before first use?
For ordinary family homes, it is not a legal requirement, but it is a sensible practice. At a minimum, thoroughly flush each outlet before first use. Formal disinfection with chlorinated water is recommended for larger projects (apartment buildings, offices, hotels), where the risk of contamination during long construction periods is higher, or for reconstructions after accidents. The procedure, concentrations, and exposure times can be found in the project documentation or in most technical manuals for piping systems.
Can I use a pipe labeled as "for water" for a drinking water supply?
Not necessarily – "for water" is a broader term that includes technical water, irrigation water, or utility water. Look for an explicit marking of "drinking water" (drinking water, Trinkwasser, eau potable) or the appropriate certificate. The most reliable indicator is a WRAS (UK), DVGW (Germany), or ACS (France) certificate stated directly on the product or in the accompanying documentation.
How long will multilayer or copper pipe last while meeting hygiene requirements?
Certified multilayer pipes are designed for a minimum lifespan of 50 years when operating conditions (temperature, pressure) defined by the manufacturer are followed. Copper pipes, when properly installed and with neutral pH water, typically last 50–70 years. A key factor is that the entire system – pipe, fittings, seals – must be of the same high quality and installed according to regulations. The weakest component determines the overall lifespan of the system.
Conclusion
Hygiene and material safety of pipes for drinking water are not abstract technical terms – they are parameters that daily affect the health of you and your family. Modern certified materials – whether multilayer pipes with a PEX inner layer or copper pipes HEPWORTH – provide a high level of hygiene safety when properly selected, installed, and operated. The decisive factor is always a holistic approach: the right material, verified certification, quality fittings, professional installation, and proper system operation. An investment in quality at the beginning is much smaller than the costs of reconstruction when problems are discovered later. And in the case of drinking water, it is also about health – an argument that should always take precedence over saving a few cents per meter of pipe.
If you want to know more about specific aspects of pipe selection, we recommend further articles in our Knowledge Center: How to choose a pipe for a drinking water supply: multilayer vs. copper vs. plastic, Installation of multilayer pipes step by step: tools, procedure, mistakes and Pressure classes PN10 and temperatures +70 °C vs. +95 °C: what they mean for your system.
Do you have a question about this topic?
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