Five systems, honestly reviewed. So you can find the filter that really suits your household.

Choosing the right option from five different methods

Anyone looking to buy a water filter is faced with a bewildering array of choices. Jug filters, activated carbon block filters, reverse osmosis, gravity filters or whole-house systems: each method has its own strengths and limitations. In this water filter comparison, we present the five most common filtration methods objectively. Not to pit one system against another, but to help you make a decision that suits your household.

The most important factors to consider are household size, the range of contaminants, mineral retention, available space and running costs. Below, we present each system along with its strengths and limitations so that you can compare them for yourself.

Ion-exchange jug filters

How they work

The principle is simple: inside the cartridge are small synthetic resin beads that exchange electrically charged particles in the water. Calcium and magnesium ions are bound and exchanged for sodium or hydrogen ions. This makes the water softer and reduces limescale build-up in the kettle. A second layer of activated carbon granules reduces chlorine and taste-altering substances. The jug simply sits on the table; no installation is required and it is ready for immediate use.

Where the limits lie

The entry-level price is low, but the range of contaminants removed remains limited. Heavy metals, pharmaceutical residues and microplastics are only captured to a limited extent. Above all, the ion exchange process removes precisely those minerals that your body needs. Depending on the manufacturer, the cartridges need to be replaced every four to eight weeks, and that adds up.

Activated carbon block filters

How they work

Activated carbon is one of the oldest and most proven filter media. It is derived from coconut shells or wood and activated at high temperatures. This creates an extremely porous surface: a single gram of activated carbon has an internal surface area of up to 1,000 square metres. Contaminants adhere to this surface (adsorption) whilst the water flows through. As a compressed block filter, often fitted under the sink, activated carbon reliably removes chlorine, pesticides and organochlorine compounds. Some models also reduce heavy metals and pharmaceutical residues. A major advantage over ion exchangers: the natural minerals in the water are fully preserved.

Where the limits lie

Nitrate and dissolved salts are not removed. A fixed water connection and installation are required, which can be an obstacle in rented properties. Filter performance decreases over time, which is why regular cartridge replacement is important. When purchasing, also pay attention to the quality of the activated carbon block: loose activated carbon granules, as found in cheaper models, filter significantly less reliably than compressed blocks.

Reverse osmosis

How it works

In reverse osmosis, tap water is forced through an extremely fine membrane under pressure. The pores of this membrane are so small that practically only water molecules can pass through. Everything else – whether pollutants, salts or minerals – is retained and flushed out with the waste water. The result is virtually pure H₂O, free from pollutants but also free from minerals. Some systems remineralise the water afterwards, but the quality of this remineralisation varies greatly depending on the manufacturer.

Where the limits lie

Depending on the system, two to five litres of waste water are produced for every litre of drinking water. Many systems require electricity and a fixed water connection. The systems are space- and cost-intensive, and the membrane must be replaced regularly. Pre- and post-filtration stages are generally recommended, which further increases complexity.

Added to this is a fundamental question: is water from which everything has been removed really the best water? The World Health Organisation points out that, in the long term, demineralised water is not ideal for supplying essential minerals. You can find a detailed comparison under MAUNAWAI vs. Osmosis.

Gravity filters with mineral ceramics

How they work

In the mountains, rainwater seeps through layers of rock. In the process, it is naturally filtered, absorbs minerals and regains its natural structure. Gravity filters utilise precisely this principle: the water is poured into an upper reservoir and flows slowly downwards through several layers of ceramic and natural minerals, driven solely by gravity. The slow flow rate is not a disadvantage, but a key factor: the longer the water is in contact with the filter media, the more thoroughly pollutants are retained. At the same time, calcium, magnesium and trace elements are preserved and, depending on the system, can even be supplemented.

Where the limits lie

Filtration takes time. Water flows gently by gravity, not at the push of a button. Capacity is limited by the upper tank, and gravity filters are not designed for large volumes of water at once. However, they require neither electricity nor a fixed water connection, making them flexible and easy to use.

Home connection systems

The all-round principle

A domestic water supply system is installed directly behind the water meter in the main pipe. All water flowing into the house first passes through the filter before reaching the individual taps. Most systems operate in several stages: a sediment filter traps coarse particles such as sand and rust, followed by activated carbon and, depending on the system, mineral ceramic stages for finer impurities. The result: filtered water at every tap in the house, whether in the kitchen, bathroom or washing machine.

Where the limits lie

Ideal for homeowners and multi-person households who want filtered water at every tap. It offers a high level of convenience in everyday life: once installed, filtered water flows everywhere. However, the one-off investment is correspondingly higher, often ranging from several hundred to several thousand francs depending on the system and the size of the house. Professional installation by a specialist firm is required, as is regular maintenance. For tenants, a whole-house filtration system is generally not an option.

What matters when making a decision

Before comparing systems, it is worth taking a look at your own situation. Four points will help narrow down the choice.

Know your water quality. Local authorities usually supply water of impeccable quality right up to the building’s exterior wall. What happens after that depends on the age and material of the building’s pipes. Old copper or lead pipes, long stand times or a domestic water tank can alter the quality. A water test will show you which substances are actually present in your tap water and which range of contaminants your filter should cover.

Plan for space and installation. Not every system fits in every kitchen. A jug sits on the table and requires no connection. An activated carbon block is fitted under the sink and requires a fixed water connection. And a mains-connected system requires space on the main pipe as well as professional installation. Consider in advance how much space you have and whether you are renting or own your home.

Estimate your daily water requirements. A single-person household will manage fine with a filter jug. A family of four needs significantly more volume per day, and a jug may reach its limits. If you want filtered water at several taps, such as in the bathroom or for the washing machine, a whole-house system is a better option.

Calculate the total costs over the system’s lifespan. The purchase price alone is not very telling. The running costs are crucial: how often does the cartridge need changing? Does the system require electricity? Is there any waste water? Calculate the cost per litre of filtered water over at least a year. A cheaper entry-level option can end up being more expensive in the long run than a system with a higher one-off investment and a long cartridge lifespan.

And one final point that applies to all systems: ask for laboratory results. A reputable manufacturer will substantiate its filter performance with independent tests and publish details of which substances are reduced and to what extent.

Our approach at MAUNAWAI

We rely on gravity filtration using Pi technology. 21 natural mineral ceramics filter out pollutants, preserve minerals and regenerate the water according to the principle of a mountain spring. No electricity, no chemicals. The Kini cartridge lasts up to three months; in larger systems such as the PiPrime, up to twelve months. Confirmed by IIREC certification and awarded top marks in the Altroconsumo comparison test for three consecutive years.

Whether as a Kini filter jug for beginners, a PiPrime gravity filter for larger households or a Peka home filter for the entire building: we have developed a system to suit every need. We publish all test results and studies transparently.