Reverse Osmosis Systems

Table of Contents

1. What exactly is a reverse osmosis system?
2. How does a reverse osmosis system work?
3. What is the difference between reverse osmosis systems and conventional water filters?
4. What are the advantages of a reverse osmosis system?
5. Who can benefit from a reverse osmosis system?
6. How does reverse osmosis water taste?
7. What should you consider when buying a reverse osmosis system?
8. Where is a reverse osmosis system connected?
9. How much does a reverse osmosis system cost?

What exactly is a reverse osmosis system?

A reverse osmosis system is a special water filter that cleans tap water particularly thoroughly. Unlike conventional filters, it not only removes coarse particles, but also dissolved substances such as heavy metals, nitrates, drug residues, and microplastics. The core of the system is a semi-permeable membrane that only allows water molecules to pass through and retains almost all other substances. Often, the term "osmosis system" is used, but it almost always refers to a reverse osmosis system. The term "osmosis" is colloquially used in a shortened form, although technically only reverse osmosis is used for water filtration. Reverse osmosis systems are often used in households to obtain drinking water of particularly pure quality – comparable to spring or distilled water. They are also suitable for sensitive applications, e.g., for baby food, aquariums, or for preparing coffee and tea.

How does a reverse osmosis system work?

The purification process in a reverse osmosis system

The following step-by-step guide shows in detail how a typical reverse osmosis system works.

1. Pre-filtration

   In the first stage, coarse particles such as sand, rust, and chlorine are removed by a pre-filter. This protects the sensitive membrane in the next stages and also improves the taste of the water.

2. Fine filtration

   Further filter stages ensure that even finer impurities are removed from the water – an important intermediate step towards optimal water purity.

3. Optional: Limescale pre-filter for heavily contaminated water

   In regions with very hard or calcareous tap water, we recommend using an additional limescale pre-filter. This protects the sensitive reverse osmosis membrane from premature calcification and significantly extends its lifespan. We install such limescale filters relatively frequently, especially for customers with highly mineralized water – a simple measure with a great effect on the efficiency and longevity of the system.

4. Reverse Osmosis Membrane

   The heart of every reverse osmosis system is the reverse osmosis membrane – a wafer-thin, semi-permeable layer that only allows water molecules to pass through. Under pressure, water is forced through this membrane. Almost all dissolved substances, including limescale, nitrate, heavy metals, microplastics, and drug residues, are retained.

5. Post-filtration (optional)

   Some systems also have an activated carbon post-filter or a remineralization stage. These ensure a particularly pleasant taste or specifically rebalance missing minerals.

6. Freshly drawn osmosis water

   The purified water is then directly available – either via a separate tap or integrated into the existing kitchen tap. It is clear, tasteless, and free of undesirable substances – ideal for daily enjoyment.

What is the difference between reverse osmosis systems and conventional water filters?

Conventional water filters – such as pitcher filters with activated carbon or simple faucet filters – primarily improve the taste and odor of tap water. They mainly reduce chlorine, limescale, and coarse impurities, but leave many dissolved substances such as nitrates, heavy metals, fluoride, or drug residues in the water. Reverse osmosis systems work much more thoroughly: through reverse osmosis technology, even the smallest dissolved substances are almost completely removed from the water. The result is significantly higher water purity that cannot be achieved with conventional filters. Another difference lies in the installation: while simple filters can be used without much effort, reverse osmosis systems are usually permanently installed under the sink. However, they deliver large quantities of filtered water at the touch of a button – without refilling or waiting.

What are the advantages of a reverse osmosis system in the household?

1. Highest water purity

Reverse osmosis systems reliably remove up to 99% of all dissolved substances from tap water. The result: clear, tasteless water of top quality.

2. Better taste and smell

Thorough filtration removes unpleasant odors and tastes. Especially when preparing tea, coffee, or baby food, the difference is clearly noticeable.

3. Fresh drinking water anytime

The filtered water is available directly at the tap – without carrying bottles, refilling, or waiting times. This saves time and increases convenience in everyday life.

4. Sustainability in the household

With a reverse osmosis system, you significantly reduce the consumption of single-use plastic bottles. This is not only environmentally friendly, but also cost-saving in the long run.

5. Protection for sensitive appliances

Pure water protects kettles, coffee machines, and other household appliances, as it is almost scale-free and does not cause deposits.

Who can particularly benefit from a reverse osmosis system?

Health-conscious households

Those who consciously want to avoid pollutants and eat as naturally as possible benefit from almost residue-free osmosis water – ideal for cooking, drinking, and preparing food.

Families with children and infants

Baby food, formula, or tea for toddlers should ideally be prepared with pollutant-free water. A reverse osmosis system offers an additional level of safety here.

People with allergies or sensitive gastrointestinal systems

In cases of intolerances or sensitive digestion, purified water can help to avoid irritation – especially if tap water contains chlorine, nitrate, or other residues.

Aquaristics enthusiasts and plant lovers

For sensitive ornamental fish, corals, or exotic plants, osmosis water is often a prerequisite for stable water values and healthy development.

Gourmets and coffee lovers

Soft, neutral water brings out the taste of tea, coffee, or high-quality foods better – free from foreign tastes and limescale.

How does filtered osmosis water taste?

Osmosis water tastes particularly neutral – free from foreign tastes, chlorine, limescale, or other interfering substances. Many users describe it as "soft", "clear", or even "smooth".

Those who are used to heavily calcareous water may notice a change at first – however, the filtered water is usually quickly perceived as pleasant and high-quality.

Especially tea drinkers, coffee lovers, or people with a fine sense of taste appreciate the purity of osmosis water. It does not distort flavors and allows food or drinks to show their natural taste.

What should you consider when buying a reverse osmosis system?

The market for reverse osmosis systems is diverse – so it is all the more important to pay attention to certain features and quality criteria when buying. Ongoing operation also plays a role if you want to benefit from clean water permanently.

Number of filter stages

Many devices work with 3 to 6 filter stages. Multi-stage systems can filter more effectively and often offer additional functions such as remineralization or UV disinfection. However, the pure number of filter stages does not say anything about the actual quality of the water treatment. Even if the impression is often given that more filter stages are automatically better, it primarily depends on the type, arrangement, and quality of the individual filters.

Quality of the membrane

The reverse osmosis membrane is the heart of the system. Look for tested brand quality and a rejection rate – ideally over 97%.

Flow rate and tank size

Depending on the household size, the system should be able to deliver enough water in a short time. Direct flow systems (also called "Direct Flow") are particularly convenient as they provide filtered water directly without intermediate storage. However, they are usually more expensive to purchase and require electricity.

Installation type: countertop or under-sink

Countertop systems are flexible and easy to install, but are more visually prominent. Under-sink systems disappear discreetly under the sink and often have a separate tap.

Maintenance & filter change

Regular filter changes are crucial for water quality. If required, we are happy to take care of the filter change for all systems we offer – uncomplicated and reliable.

Certifications & materials

Important seals of approval (e.g., NSF, TÜV) and food-grade, BPA-free materials provide safety – especially if the water is consumed daily.

Countertop or under-sink reverse osmosis system?

Most reverse osmosis systems are installed as under-sink systems directly under the kitchen sink. There, they are connected to the cold water line and the drain. The purified water is provided either via an additional tap or via a 3-way faucet system that carries both tap and osmosis water.

Alternatively, there are , which do not require a permanent installation. These are simply connected to the faucet and are ideal for rented apartments or temporary use.

How complex is the installation?

The installation effort depends on the system:

Good to know:

Many modern systems are now designed to be low-maintenance and user-friendly – including quick-release couplings, color-coded hoses, and easily replaceable filter modules.

What are the costs for a reverse osmosis system?

The cost of a reverse osmosis system depends heavily on the model, features, and installation effort. Basically, the price can be divided into three categories:

1. Countertop systems – mobile & compact

These simple systems are available from €1000. They are suitable for rented apartments or occasional use, but usually offer lower flow rates and less convenience.

2. Under-sink systems – permanently installed

High-quality systems for permanent use start at approx. €1000. Models with multiple filter stages, direct flow function, or remineralization can cost up to €2500 or more.

3. Operating costs – filter change & maintenance

The running costs mainly arise from regular filter changes – depending on the model and use, these amount to approx. €50-150 per year. High-quality systems require less frequent maintenance and are often cheaper to maintain in the long run. The Evofilter, for example, only requires a filter change every 3 to 5 years – which saves time and follow-up costs.

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