Choosing a filter for water often starts with the question: which system will be the best? Meanwhile it is better to start with another issue – what problem with water do we want to solve?

A different solution is required for water with an unpleasant taste and odour, another visible sediment, and yet another high hardness causing the build-up of limescale on taps and appliances in the home. The source of water is also important – other needs may arise in the case of tap water, and other when using one’s own water source.

That is why there is not a single water filtration technology suitable for every home. Mechanical filtration of every home. Filtration mechanical of every home. Filtration mechanical of every home. Filtration mechanical of every home. Filtration mechanical of every home. Filtration mechanical of every home. Filtration every home. Mechanical filtration, activated carbon, ultrafiltration, reverse osmosis or water softening meet a various needs and are often combined with each other .

How then do you choose the right method for treating water?

Where do you start when choosing a water filtration system?

The first step should be to assess the water quality and the desired outcome. It is worth asking yourself a few questions:

• Do we use mains water or water from our own supply?
• Is there any sand, rust or other sediment in the water?
• Does its taste or smell bother us?
• Do limescale deposits build up quickly on taps, shower cubicles and fittings?
• Is the filter intended solely to treat water for drinking, or to treat water throughout the house?
• Do we require very thorough filtration and the removal of dissolved substances?
• Do we want to retain most of the minerals that occur naturally in water?

In the case of water from a private supply, it is also particularly important to carry out the appropriate tests. Only once the water’s parameters are known can the appropriate water treatment technology be selected.

What are the most common water-related problems in the home?

Just because water looks clean does not mean that every filtration system will treat it in the same way. Different technologies work in different ways.

Sediment, sand and rust

Particles visible in the water may originate, amongst other things, from the plumbing system, works being carried out on the water supply network or, in the case of a private water intake, from the water source. In such situations, the primary solution is mechanical filtration.

Unpleasant taste or smell

Tap water may, amongst other things, have an odour associated with the disinfection methods used. Filtration using activated carbon is often used to improve the organoleptic properties of the water.

Hard water and limescale

The white limescale that appears on taps, shower cubicles, kettles or parts of household appliances is most often caused by hard water. If the problem affects the whole house, it is worth considering a central water softener, rather than just a filter fitted under the sink.

The need for thorough filtration of drinking water

If the aim is to significantly reduce the levels of many substances dissolved in water, one solution is reverse osmosis. If, on the other hand, the primary aim is to retain fine suspended solids and particles whilst retaining most of the dissolved minerals, ultrafiltration may be worth considering.

Mechanical filtration – basic protection of the system

Mechanical filtration is one of the simplest, yet most important, stages of water treatment. Its purpose is to remove undissolved impurities, such as:

• sand,
• rust,
• silt,
• small settlements,
• particles originating from the plant.

To this end, foam and cord filters with a specified filtration accuracy are used, amongst other things.

Filtration mechanical can be used both on its own, as well as as a stage in a more advanced water treatment system. The removal of larger impurities helps to protect subsequent stages of the installation and filter cartridges .

Carbon filtration – a way to improve the taste and smell of water

Another widely used technology is filtration using activated carbon. Its structure enables it to absorb specific substances present in water. In domestic filtration systems, carbon cartridges are used, amongst other things, to reduce chlorine levels and improve the taste and smell of the water.

Carbon filtration is very often used in conjunction with other water filtration methods. It can form part of a flow-through filter, an ultrafiltration system or a reverse osmosis system. In RO systems, the carbon filter cartridge also performs an important function – it prepares the water before it comes into contact with the osmotic membrane.

Ultrafiltration – when should an ultrafiltration membrane be used?

Ultrafiltration, abbreviated to UF, is a membrane technology. The ultrafiltration membrane acts as a highly effective mechanical barrier. It retains fine suspended solids, particles causing turbidity and many microorganisms. At the same time, most of the substances present in the water in the form of dissolved ions pass through the membrane. This means that ultrafiltration does not cause as significant a change in the mineral composition of the water as reverse osmosis.

Therefore ultrafiltration may be used when:

• we use tap water,
• we want to provide additional protection for the water against fine particles and suspended solids,
• We are keen to preserve the majority of naturally occurring minerals,
• We do not need to significantly reduce the amount of dissolved salts.

It is worth bearing in mind that the ultrafiltration membrane alone does not perform all the functions of the entire filter. For this reason, in domestic ultrafiltration systems, it is often combined with mechanical filtration, carbon filtration or additional filter media.

Reverse osmosis – thorough filtration of drinking water

Reverse osmosis, or RO – Reverse Osmosis, also uses a membrane, but it works differently to ultrafiltration. Water under sufficient pressure flows through a semi-permeable membrane. As a result, some of the water is separated from the majority of the dissolved substances it contains. RO technology enables a significant reduction in, amongst other things, many dissolved salts, ions and other compounds present in the water.

That is why reverse osmosis is a solution used primarily when we require very thorough filtration of water intended for drinking and food preparation. The reverse osmosis system itself usually consists of several stages. Mechanical and carbon filters may be located upstream of the membrane, whilst downstream filters include, amongst others, those designed to improve the taste and odour of the water or to add minerals.

Both traditional systems using a water storage tank and modern Direct Flow solutions, which treat water on demand, are available on the market.

Reverse osmosis or ultrafiltration – how do these technologies differ?

Reverse osmosis and ultrafiltration both use membranes, but they serve different purposes:

• Reverse osmosis enables a very significant reduction in the amount of substances dissolved in water.
• Ultrafiltration acts primarily as a highly precise barrier against insoluble particles. Most dissolved mineral components remain in water.

The choice should therefore not depend on which technology is ‘better’, but on what effect we wish to achieve with the water filtration. If thorough filtration and a significant reduction in many dissolved substances are the most important factors, it is worth considering a reverse osmosis system. If you use tap water and wish to filter it whilst retaining the minerals dissolved in it, ultrafiltration may be the solution.

Hard water – is a filter under the sink enough?

This is one of the most common misunderstandings regarding the choice of a filtration system. If limescale only forms in the kettle, you can minimise it by using a water filter fitted under the kitchen sink. However, if limescale also forms:

• on batteries,
• in the shower,
• on the heating elements,
• in the washing machine,
• in the dishwasher,
• in the heating system,

The problem affects the water supply throughout the building. In this case, an under-sink filter is not the solution. You should consider a central water softener.

Water softeners use an ion exchange process designed to reduce the levels of calcium and magnesium ions responsible for water hardness. It is worth distinguishing between two solutions here, each catering to different needs:

• under-sink filter – preparing water for drinking and cooking,
• water softener water – reduction in hardness of the water throughout the whole house.

Can different technologies for water filtration be combined with each other?

Yes! In practice, this is a very common solution. A multi-stage filtration system may utilise several technologies, each of which performs a different function. An example system might include:

mechanical filtration → carbon filtration → ultrafiltration membrane or osmotic membrane → mineralisation.

The mechanical filter traps larger particles in the water. Activated carbon is responsible for reducing certain substances, including chlorine, and for improving the taste and smell of the water. The membrane carries out the actual stage of thorough water purification. Finally, the system can be supplemented with mineralisation cartridges. This is precisely why, when choosing a water filter, it is worth analysing not only a single cartridge or membrane, but the entire system design and the function of the individual filtration stages.

How do you choose a filter for water in your home?

The most important rule is to match the water filtration system to the actual problems. If our main priority is to improve the taste and smell of tap water, a complex reverse osmosis system is not always necessary. If you want to filter the water more thoroughly whilst retaining most of the dissolved minerals, it is worth considering a system with an ultrafiltration membrane. If you are looking to significantly reduce the levels of many substances dissolved in drinking water, a under-sink water filter – a classic reverse osmosis system or a direct-flow system – would be the right choice. However, if the main problem is limescale affecting the whole house, you should opt for a central water softener installed at the building’s water inlet.

Choosing a filtration system starts with a proper assessment of your needs

Modern water treatment does not rely on the use of a single, universal filter. It involves selecting the appropriate processes based on the water quality and the user’s needs. Mechanical filtration, activated carbon, ultrafiltration, reverse osmosis and water softening each serve different purposes. They can operate independently or form a multi-stage system. Therefore, before choosing a solution, it is worth determining:

• what is in the water,
• what we want to limit or remove from it,
• where the treated water will be used,
• what level of performance do we need,
• Should the filtration system cover a single tap or the entire building?

Only on this basis can you choose a technology that truly meets the needs of a particular household.

FAQ – frequently asked questions about the types of water filtration systems and how to choose one

Which filter for tap water should you choose?

The choice depends on the water parameters and the desired outcome. Carbon filtration, amongst other methods, is used to improve taste and odour. If a more effective mechanical barrier is required, ultrafiltration may be considered, whilst reverse osmosis is suitable where a significant reduction in dissolved substances is needed.

Does ultrafiltration remove limescale from water?

The UF membrane alone does not remove the dissolved calcium and magnesium ions responsible for water hardness. If limescale is a problem throughout the system, a water-softening solution should be considered.

Does reverse osmosis soften water?

An RO membrane significantly reduces the concentration of many dissolved ions, including those responsible for water hardness, but it operates at the point of use. An under-sink RO filter therefore does not replace a central water softener that protects the entire domestic plumbing system.

Can a water softener be connected to a sink filter?

Yes. Both devices have different functions. A water softener can reduce the hardness of the water throughout the whole building, whereas the filter under the sink is responsible for additional treatment of water intended for drinking and cooking.

Is reverse osmosis always the best solution?

Nie ma jednej technologii najlepszej w każdej sytuacji. RO zapewnia bardzo dokładną filtrację i szeroką redukcję substancji rozpuszczonych, jednak w przypadku innych potrzeb wystarczające lub bardziej odpowiednie mogą być ultrafiltracja, filtracja węglowa albo inne metody uzdatniania. Najważniejsze jest dopasowanie systemu do jakości wody i oczekiwanego efektu.