Stainless Steel Pipes and Drinking Water – Certificates, Safety, What to Watch For

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Stainless steel hoses and drinking water – certificates, safety, what to look for

When an installer or a DIY enthusiast, even a highly experienced home handyman, connects a faucet under the sink, most of the attention is directed at ensuring that the connections do not leak and that the hose has the correct length. Rarely does anyone stop to consider a question that is far more important from a hygiene perspective: is this particular hose actually intended for contact with drinking water? Is it certified? What material are its internal parts made of? And what about the seals – can they affect the taste or safety of the water?

These questions are not arbitrary or paranoid. In practice, it can happen that hoses made from materials certified only for technical water, not for drinking water, reach the market – and the customer is completely unaware of it, because the product looks exactly the same as a certified one. The difference is not visible to the eye. It is found in the documentation, in the composition of the rubber, in the quality of the stainless steel, and in whether the manufacturer can prove testing in an accredited laboratory.

In this article, we will break down the entire issue into smaller parts – from the legislative framework through specific certificates to practical tips on what to check when purchasing and installing.

Why is certification for drinking water even necessary?

Water in households is not chemically neutral. It contains dissolved salts, chlorides, in some regions increased amounts of calcium and magnesium, and possibly trace amounts of chlorine added during treatment. These substances react with the materials through which the water flows. If the material is unsuitable, it can lead to:

Migration of heavy metals (lead, cadmium, nickel) into the water,
Release of organic compounds from plastics or rubber seals,
Microbiological growth on porous inner surfaces,
Corrosion of connections and subsequent changes in the color or odor of the water.

That is why legislation exists that clearly defines which materials are allowed to come into contact with drinking water and what tests the products must pass. It is not just a formality – it is direct protection of health.

Legislative framework – which standards apply in Slovakia and the EU

In Slovakia, the issue of materials in contact with drinking water is governed by several legal provisions and technical standards. The foundation is formed by:

Act No. 355/2007 Coll. on the protection, promotion and development of public health and its implementing regulations, which set hygiene requirements for drinking water and materials that come into contact with it.
Government Regulation No. 247/2017 Coll. on the details of the quality of drinking water – defines quality indicators and limit values for monitored substances including metals.
EU Directive 98/83/EC on the quality of water intended for human consumption (revised by Directive 2020/2184/EU), which introduces harmonized rules at the European level for materials in contact with water.
Regulation (EU) 2020/2184 – the new directive on drinking water, which significantly strengthens the requirements for materials and products in contact with drinking water. Member states had the obligation to transpose it by January 2023.

From the technical standards, the following are key:

EN 15664 – testing of metal migration from materials into drinking water,
EN 16421 – organic materials in contact with drinking water,
EN 13280 and related standards for stainless steels in sanitary applications.

In practice, this means that a serious manufacturer of hoses for drinking water must have test protocols from accredited laboratories proving that their product meets the migration limits for metals and organic substances set by the standards.

Specific certificates and what they mean

On the European market, there are several certification systems that you may encounter when choosing hoses. Not all are equal and not all are relevant to the Slovak market. Here is an overview of the most important ones:

WRAS (Water Regulations Advisory Scheme)

A British certification system managed by the Water Regulations Advisory Scheme organization. It is one of the most prestigious in Europe and is recognized in many countries outside the UK as well. WRAS certification includes testing of materials according to strict British standards BS 6920 and includes:

Testing for toxicity (sensory properties – taste, odor, color of water),
Microbiological support of growth (whether the material supports the multiplication of bacteria),
Migration of substances into water at various temperatures and pH levels.

The WRAS certificate is time-limited and must be renewed, which means the manufacturer is under continuous control.

KTW (Kunststoffe und Trinkwasser)

A German system for assessing plastic materials in contact with drinking water. Managed by the Federal Institute for Risk Assessment (BfR). For hoses, it is relevant mainly regarding the plastic braiding or the plastic outer layer of the hose. The KTW positive list contains a list of approved polymers and additives.

DVGW (Deutsche Vereinigung des Gas- und Wasserfaches)

The German technical and scientific association for gas and water. DVGW certification (according to work sheets W 270, W 543 and others) is very widespread in German-speaking countries and Central Europe. For hoses for drinking water, DVGW W 270 is essential – it tests the microbiological safety of materials.

ACS (Attestation de Conformité Sanitaire)

French certification system. Similar to WRAS, it includes comprehensive testing of organoleptic properties (taste, odor), substance migration, and microbiological safety. It is mandatory on the French market and is considered a quality proof in other EU countries.

Hygienic assessment / Hygienic certificate

In the Slovak and Czech markets, you may also encounter the term "hygienic certificate" or "hygienic assessment" issued by the relevant public health authorities. It refers to the evaluation of a specific product to determine whether it meets the hygienic requirements for contact with drinking water according to current legislation. This document should be available from the manufacturer or importer.

CE marking – what it says and what it doesn't

CE marking is mandatory on the EU market for many product categories, but by itself it says nothing about suitability for drinking water. CE marking indicates conformity with the essential requirements of the relevant directives (e.g., the Construction Products Directive, the Pressure Equipment Directive), but it does not test the hygienic safety of materials in contact with water. A hose with CE marking can be certified for drinking water – or it may not be. CE marking alone is not sufficient.

Materials of the hose and their impact on reliability

Stainless steel hose is not made of one material – it consists of multiple layers and components, each of which can potentially affect water quality. Let's go through them one by one:

Inner hose – rubber or EPDM

In most braided stainless steel hoses, the inner tube is made of EPDM rubber (ethylene-propylene-diene monomer) or, less commonly, NBR rubber. EPDM is the preferred choice for drinking water – it has good resistance to chlorine, UV radiation, and a wide temperature range. A certified EPDM inner tube must be tested for migration of organic substances (plasticizers, antioxidants, vulcanization accelerators) and for microbiological safety.

Cheaper hoses may contain an inner tube made of NBR or PVC with an unsuitable composition – these can release substances with unpleasant odors or potential health risks into the water. The problem is usually visible (or noticeable) in that the water from the device smells like rubber, especially after a long period of inactivity.

Stainless steel braid – type of steel

The outer stainless steel braid primarily has a mechanical function – it protects the inner hose from damage and transmits the pressure load. It usually does not have direct contact with drinking water, but in the case of a leak in the inner tube or condensation, it may come into contact with moisture. The key parameter is the type of stainless steel:

AISI 304 (1.4301) – standard stainless steel, 18 % chromium, 8 % nickel. Suitable for most installations with normal water.
AISI 316 (1.4401) – contains an additional 2–3 % molybdenum, which significantly increases resistance to chlorides. More suitable for areas with hard or highly chlorinated water and in more aggressive environments.

In normal household conditions, AISI 304 is sufficient. For industrial or food industry applications, AISI 316 is preferred.

End fittings – brass or stainless steel

This is where the most action happens in terms of drinking water. End fittings are in direct and continuous contact with water – water flows through them, and it stagnates in them when the flow stops. Therefore:

Brass fittings – contain copper (60–70 %) and zinc (30–40 %), possibly trace amounts of lead. Older brasses contained up to 3 % lead as a machinability additive. Modern brasses (so-called "lead-free" or "low-lead") must meet limits according to EN 12165 and must be tested for lead and zinc migration. When purchasing, check whether the manufacturer declares brass OT58, CW617N (common brass) or CW511L (low-lead brass) and whether there is a certificate confirming compliance with migration limits.
Stainless steel fittings – more hygienically advantageous, they do not contain lead or zinc. Metal migration is minimal. The disadvantage is the higher price and sometimes worse machinability when producing complex shapes.

Learn more about this comparison in the article Stainless steel vs. brass fittings – what's the difference and what to choose in our Knowledge Center.

Seals (O-rings, flat seals)

Seals are made of rubber or synthetic elastomer. Even with a fully certified hose, replacement seals may be unsuitable if made from the wrong material. For drinking water, it is recommended to use seals certified according to WRAS or KTW, made from materials such as EPDM or NBR with a hygiene certificate. Always use replacement parts from the same manufacturer or explicitly certified for drinking water when replacing seals.

What to specifically ask when buying – practical checklist

From practice, I know that most customers when buying a hose don't pay attention to anything except length and thread diameter. Yet, a few minutes spent on the following points can clarify the differences between products in a significant way:

Is the hose explicitly labeled "for drinking water"? Some manufacturers sell visually identical hoses in two versions – for drinking and for technical water. Check the name or technical specifications.
What certificate does the hose have? Ask for WRAS, KTW, DVGW or a national hygiene certificate. If the manufacturer/seller cannot provide any, treat the product as not certified for drinking water.
What material is the inner hose made of? A declaration of "EPDM" is a good start, but the quality of EPDM is not determined by the type of rubber alone – key are the additives. Look for "certified EPDM for drinking water" or a direct reference to a standard.
Type of brass fittings – for brass fittings, look for a declaration of "lead-free" or a specific alloy designation (CW511L).
Maximum pressure and temperature – certification for drinking water refers to defined conditions. Common household hoses are typically certified up to 10 bar and 70 °C. For higher parameters (e.g. solar systems), the conditions differ.
Is the manufacturer available and traceable? Find the manufacturer, check their website and availability of technical documentation. Anonymous distributors without an identifiable manufacturer are a risk.

Specific products – what does the PROFI range offer on atria.sk

In the category of stainless steel hoses on atria.sk, you will find products of the PROFI range, which are explicitly intended for drinking water. Let's look at them from the perspective of this article:

The flagship product in terms of material quality is Stainless steel extendable hose PROFI S for drinking water with stainless steel fittings (1/2" FF, 50–100 cm). This hose has stainless steel (not brass) fittings, making it the most hygienically clean option – no brass in contact with water, no risk of lead or zinc migration. For customers who want maximum hygiene without compromises, this is the right choice. The extendable system in the range of 50–100 cm makes it practical even in situations where the exact distance is not clear in advance.

For standard installations in the bathroom and kitchen, various versions of the PROFI MW range – plastic-coated hoses with brass fittings – are available in various dimensions and thread sizes. Version 3/8" FF in the range of 30–60 cm is a typical choice for connecting a sink trap or a faucet with a smaller thread, while version 1/2" FF, 40–80 cm covers most standard installations under the sink or to a WC fill valve.

For situations where the distance between the connection and the faucet is significantly greater – for example, in the case of a non-standard location of the faucet or during a bathroom renovation – there is PROFI MW 1/2" FF in the range of 80–160 cm. Such a length is suitable, for example, for connecting a freestanding sink or in the case of a non-standard arrangement of the manifold and the faucet.

If you are deciding whether to choose a plastic-coated stainless steel hose or a bare stainless steel hose, I recommend reading the article Plastic-coated stainless steel hose vs. bare stainless steel – which is better. In short: the plastic coating protects the braid from mechanical damage and condensation, and has no effect on the internal hygiene properties of the hose.

Water stagnation in the hose – an underestimated risk

One of the less discussed topics is the microbiological safety of water that stagnates in the hose for a longer period. This happens, for example:

after a vacation, when water has not been used for several days or weeks,
in rarely used spaces (summer homes, rentals between tenants),
in blind branches of the piping (forgotten outlets).

Stagnant water in the hose leads to the growth of microorganisms, in the worst case even to the multiplication of Legionella. Key factors influencing this:

Water temperature – Legionella multiplies most intensively at 25–45 °C, which is a range typical for cold water in a warm environment (e.g., in summer in a poorly insulated space under the sink).
Material of the inner wall – porous or chemically inappropriate materials promote the formation of biofilm, on which bacteria attach.
Length of the hose – shorter hose = smaller volume of stagnant water = lower risk.

Certified hoses (WRAS, DVGW W270) are tested precisely for their resistance to the growth of microorganisms. Hoses without certification may have an inner surface that actively promotes biofilm formation. For this reason, never use hoses certified only for central heating or technical water for drinking water – their inner surface is not tested for microbiological safety.

Practical tips for installation from a hygiene perspective

Even a certified hose can cause hygiene problems if it is improperly installed or stored. From practice, here are a few recommendations:

Rinse the hose before installation – after storage or a long time in the store, there may be remnants of talcum powder (used in the production of rubber tubes) or other impurities inside. A quick rinse with clean water before first use is a good habit.
Do not use Teflon tape on compression fittings – if the hose has a rubber gasket, it does not need Teflon tape. Improper winding can cause leakage and at the same time deform the gasket.
Do not over-tighten the connections – with aluminum or brass threads, over-tightening can crack the thread or deform the gasket. A tight thread should be tightened by hand and then tightened with a wrench by a maximum of a quarter turn.
After installation, let the water run for at least 30 seconds – to flush out any residues from the inside of the new hose.
Regularly check the condition of the hoses – the recommended replacement is every 5–10 years, or immediately in the case of any mechanical damage to the braiding or water leakage. More about the lifespan can be found in the article How long does a stainless steel hose last and when to replace it.

Typical mistakes from practice – what actually happens

Over the years in the industry, I have encountered several recurring scenarios worth noting:

A customer bought a cheap hose from a bargain e-shop. After two weeks, he reported that the water from the shower smelled like rubber. The hose was not certified for drinking water – it had an NBR inner tube apparently full of unsuitable plasticizers. Replacing it with a certified EPDM hose immediately solved the problem. The price difference was just a few euros. The quality difference was significant.

A plumber used a heating hose for drinking water. Visually identical hoses, same appearance, different inner material. Hoses for heating are often made from materials optimized for hot water in a closed circuit – they may contain antioxidants and corrosion inhibitors that do not belong in drinking water. Always check what the specific hose is intended for.

A customer was looking for a specific thread size but did not check the certification. He came with an exact requirement: „1/2 inch, length 60 cm“ – and that is fine. But when we started to talk about what he was actually buying, it turned out that he had chosen a hose with no information on its certification. After supplementing the documentation, we compared the products and redirected him to a certified variant. You can read about the thread size and length in the articles 3/8" or 1/2" thread – how to find out what you need and What length of hose suits me – fixed or extendable? Here I want to emphasize: even if you have the parameters right, certification must always go hand in hand.

Residential house with long-uninstalled hoses. During the bathroom renovation, 15-year-old hoses were found under the old sink. They looked good visually – the braiding was undamaged, no visible corrosion. However, the inner rubber was degraded after 15 years, brittle, with micro-cracks. Such a hose can burst at any time and cause water damage. A general recommendation is to replace them every 10 years regardless of their visual condition.

How pressure and temperature are considered in certification

Certification for potable water is always tied to specific operating conditions. In a typical apartment building, the pressure of cold water is 2.5–5 bar, and the temperature of hot water at the tap is typically up to 65 °C. Standard hoses for household use are tested for:

maximum working pressure: 10 bar (typical range 8–10 bar),
maximum temperature: 70–90 °C (depends on the specific product),
pressure test: typically 20 bar (double to triple the working pressure).

For special applications – for example, direct connections in solar systems or high-pressure circuits – standard hoses are not sufficient. Special hoses certified for higher temperatures and pressures are required there. However, common hose connections in the bathroom and kitchen are well below these limits and standard certified hoses fully meet the requirements.

Most frequently asked questions (FAQ)

Can I use a stainless steel hose without a potable water certification if it looks good?

No – this approach is unreasonable in a plumbing installation with potable water. The external appearance says nothing about the internal material. A low-quality inner hose can release organic compounds into the water, promote bacterial growth, or degrade over time and cause a failure. The price difference between certified and low-quality hoses is minimal, while the risk is disproportionately high. Always insist on products explicitly designed for potable water.

Is CE marking sufficient to guarantee that a hose is suitable for potable water?

No. CE marking confirms compliance with relevant EU directives (construction products, pressure equipment), but does not test the hygienic safety of materials in contact with potable water. For potable water, look for specific certifications such as WRAS, DVGW, KTW, ACS, or a national hygiene certificate. CE marking and potable water certification are two different things that do not automatically complement each other.

Are brass fittings safe for potable water?

Yes, if they are made of brass certified for potable water. Modern brass with low lead content (marked as CW511L or "lead-free brass") meets European limits for metal migration into drinking water. The problem can be old or low-quality brass with higher lead content. When buying a hose with brass fittings, check whether the manufacturer declares low-lead brass or has a certificate confirming compliance with migration limits according to EN 15664.

How long is a hose certification valid – does it need to be renewed?

Certifications such as WRAS are valid for a limited time (usually 5 years) and must be renewed, which includes retesting. This is beneficial for the consumer – the manufacturer is under continuous control. Manufacturers with old certifications or certifications from unknown organizations can be problematic. You do not need to track the validity of the certification for your specific product – it is the manufacturer's responsibility towards the certification body. As a buyer, you only need to ensure that the product currently has a valid certification.

What to do if the hose smells after installation or the water has an odd taste?

The first step is to let the water run for 2–3 minutes – if the problem disappears, it is likely residue from the manufacturing process that has been flushed out. If the problem persists, the hose is likely not suitable for potable water or has a low-quality inner material. In this case, replace the hose with a certified product. Never drink water that has a persistent rubbery or chemical smell – at minimum it is unpleasant, in the worst case it may indicate the migration of undesirable substances.

Do I need a different type of hose for cold and hot water?

Standard certified hoses for potable water are designed for both circuits – cold and hot water up to temperatures typically around 70–90 °C. In a household, the hot water from the tap does not reach higher temperatures, so one type of hose can handle both. You need to differentiate only in special applications (solar systems, industrial equipment), where temperatures can be higher – in those cases, special hoses for higher temperatures are required.

Conclusion – the hygiene of potable water also depends on small details

A stainless steel hose under the sink is a small component that receives minimal attention. And yet – every day water flows through it that you drink, cook with, and use to brush your teeth. This is not a reason for panic, but it is a reason to spend a few moments checking the certification and materials when purchasing.

Summary of the most important points: always buy hoses explicitly designed for potable water, with a verifiable certificate (WRAS, DVGW, KTW, ACS or hygiene certificate), with an EPDM inner tube and fittings made of certified brass (low-lead) or stainless steel. Hoses from the professional range at atria.sk meet these criteria and are available in various lengths and thread sizes for different types of installations.

If you are still unsure about the right length or thread for your installation, I recommend reading other articles in this Knowledge Center – for example How to choose the right stainless steel hose for potable water or Installation of a stainless steel hose under the sink or at the tap. You can also find a whole range of practical information in Common questions about stainless steel hoses – threads, lengths, pressure, replacement.

Do you have a question about this topic?

Are you unsure or dealing with a specific situation in your home? Write to us – we are happy to help.