Which water filter to pick?

on April 3, 2025

We answer the most common question: “Which water filter to pick?” and present the construction of a classic reverse osmosis system.

Let’s start with the basics

What exactly is a water filter? We want to provide general answers because we often encounter this question during phone calls. This material will help you understand the basics, making our conversations more specific and effective. It’s better to explain everything once and then answer individual questions.

Which filter to choose?

This is the most important and frequent question:
– Which filter will be right for us?
From our side, we always ask:
– What goal do you want to achieve? What kind of water do you want to get? Are you interested in clean utility water from a well, or drinking water from the municipal supply?
The answer to the question “which water filter to choose” depends on the type of incoming water and the purpose – that is, what kind of water you want to obtain: utility or drinking water.

Water filter for well water

If we talk about a filter for well water, water analysis and capacity determination are necessary. You send us your data, and we select a water treatment system individually. We have a rich portfolio – we encourage you to check it out. You will find many examples of installations we have completed. Although some may look similar, each one is individually tailored: to the water analysis, demand, and installation location.

Reverse osmosis – a solution for clean drinking water

If we talk about systems for drinking water, these are usually ready-made sets. As the official representative of the European filter manufacturer Bregus, we offer Bregus reverse osmosis systems. Let us explain the construction of a classic system using the example of Bregus Classic Silver.

Pre-filter housings

For those who do not yet know classic reverse osmosis systems – the basic model has 5 stages. Bregus Classic Silver has as many as 7, and the most popular model is the 8-stage version. The system always contains housings with pre-filters that remove most mechanical and chemical impurities. The first cartridge – mechanical, 5 microns – retains rust, silt, and sand. The second – carbon – removes hydrogen sulfide and chlorine, which damages the membrane. The third cartridge – mechanical, 1 micron. These three cartridges are so-called pre-filters, often sold as a set.

Osmotic membrane

The membrane is the heart of the system – a replaceable element that removes salts and bacteria. It ensures the highest quality drinking water, compliant with European standards.

Post-filters

In basic models, the fifth stage is a carbon filter. In modern systems, you will also find a mineralizer (6), Bioceramic structurer (7), and alkaline filter (8).

Types of cartridges in RO systems

Pre-filters (10”) should be replaced every 6 months. You can do this yourself – the set includes a housing wrench.
The membrane (75 GPD) removes salts. It has one inlet and two outlets: the center – drinking water, the edge – waste to the sewer. Thanks to this, the water filter provides the highest quality.
Wastewater contains: impurities <1 micron, dissolved salts, viruses, bacteria. This water can be drunk without boiling – in my family, I gave it to my child from the 6th month (after consulting a pediatrician).

RO system components

The four-way valve cuts off the water supply when filtration is not needed – it saves cartridges and water.
The flow restrictor 420 maintains pressure in the membrane and prevents water from bypassing it.
For proper operation, 3 atmospheres of pressure are needed. If there is none – the set includes a pump, and a socket under the sink is also required.
The set includes: a tee for cold water, a clamp for the siphon, a separate faucet, and a storage tank.

RO tank

The tank stores water because filtration through the membrane is slow (the stream is thinner than a matchstick). If there is sufficient pressure, more water accumulates in the tank. A typical tank holds up to 10 liters – ideal for cooking.