The right filter depends on your needs — water quality, available space, budget, and the level of filtration you want. At Holmblad Water, we offer three main solutions: 1-stage filters, multi-stage filters, and reverse osmosis systems.
1-Stage Solutions
A 1-stage solution might at first sound like the least effective type of filter, but a high-quality 1-stage filter can today deliver very impressive filtration.
All our 1-stage filters use the latest generation of coconut-based activated carbon block filters – the most effective form of carbon filtration. These cartridges can remove more than 100 different impurities from drinking water, have a lifespan of up to 24 months, and can filter up to 36.000 liters of water.
1-stage filters are available in several versions:
Coconut-based activated carbon block cartridge
Coconut-based activated carbon block cartridge with polyphosphate for scale prevention
Coconut-based activated carbon block cartridge with pre-filter for dirt and particles
Coconut-based activated carbon block cartridge with ultramembrane against bacteria such as E. coli
Advantages of 1-stage solutions:
Space-saving installation, leaving plenty of room under the sink
Effective filtration of 100+ impurities, including PFOA, PFOS, pesticides, microplastics, heavy metals, and pharmaceutical residues
Options for both bacteria and scale filtration
Maintains a strong and practical water pressure
Preserves all healthy minerals
Low annual cartridge costs
Multi-Stage Solutions
A multi-stage solution allows you to combine different types of filtration and dedicate each cartridge to a specific task. For example, a dedicated pre-filter can better handle a larger amount of dirt, or two carbon block cartridges can be combined to increase overall filtration. The two carbon block cartridges can also be combined with both scale and bacteria filtration.
Advantages and considerations:
2- and 3-stage systems are still compact (typically 32–34 cm high, 25 cm wide, and 9–15 cm deep)
Can provide even higher filtration than 1-stage solutions
More combination options
Water pressure may be reduced slightly more than with 1-stage solutions
Preserves all minerals
Slightly higher annual cartridge costs
Reverse Osmosis
Reverse osmosis is known for removing virtually all impurities from water and is the most effective drinking water filtration method available today. However, reverse osmosis systems are also known for removing healthy minerals, being difficult to install, cumbersome when changing cartridges, taking up a lot of space, wasting large amounts of water, and having low and impractical water pressure.
Our Blackline reverse osmosis system, however, solves many of these challenges with only three cartridges, which can be replaced in seconds without shutting off the water. The system also makes far better use of water, with a filtered water to wastewater ratio of 2.5 to 1. It can deliver up to 3.5 liters per minute, making it more practical than traditional systems, and it has no external tank, which makes it significantly more space-saving. Blackline also comes with an external cartridge that adds healthy minerals back into the water.
Advantages of Blackline reverse osmosis:
Space-saving installation (46 × 17 × 43 cm) and no external tank
Water flow of 3–3.5 liters per minute
Low water waste (2.5:1 ratio)
Lower cartridge operating costs than traditional systems
All 1, 2 and 3 stage filters are delivered complete and ready for installation and you only have to connect the included hoses to your cold water outlet and your tap. Installation can be done in 10 min. with a small wrench.
Cartridge change is done easy and quickly as well, with all our different types of filter housing, and wrench is included where needed.
The Blackline reverse osmosis system is a more complicated system to install and if you are not comfortable installing this yourself you should contact a plumber
All our water filter cartridges consist of pure coconut-based activated carbon.
Coconut-based activated carbon is made from coconut shells, which are a surplus/waste product from an already sustainable coconut production, where no trees are felled, thus providing a sustainable and long-term source of raw material.
Additionally, all water is utilized, and even our Blackline reverse osmosis system has a water efficiency of 2.5:1 (2.5 liters of drinking water to 1 liter of wastewater), where classic reverse osmosis systems can have an efficiency of up to 1:8
PFAS consists of up to 15,000 different chemicals, and many of these are extremely difficult to filter out of drinking water.
The so-called long-chain PFAS substances, such as PFOS, PFOA, and PFNA, are among the most widespread in drinking water and are now found in up to 50% of all water samples.
One of the absolute best and most commonly used methods for effectively filtering long-chain PFAS substances is coconut-based activated carbon block filtration. When the carbon is compressed into a carbon block, it creates an enormous surface area, which provides unmatched absorption capacity. This ensures an effective reduction of PFAS substances to well below the regulatory limits. Coconut-based activated carbon block filtration is also an integral part of all efficient reverse osmosis filtration systems and is used, among other things, to reduce PFOA, PFOS, and PFNA.
All our filtration solutions use coconut-based activated carbon block filtration. Several solutions are also combined with ultramembrane filtration, but it is the carbon that handles the PFAS filtration, while the ultramembrane exclusively filters bacteria and certain viruses out of the water.
For a high PFAS filtration, we offer solutions with two combined carbon block cartridges, which enhances the ability to filter PFAS substances. This applies to the models Coco Duo+ and Activo Duo+. These models double the surface area and contact time with PFAS substances, ensuring even more effective filtration.
For the highest possible filtration of all types of PFAS our Blackline RO reverse osmosis system is the best solution and will offer a filtration of up to 99% of all PFAS substances.
Tap- and pitcher filters generally rely solely on filtration through granular activated carbon. While granular activated carbon is effective in removing odor and taste, as well as a small range of impurities, the limitation with this type of filter is that they often contain a very small amount of activated carbon and "only" use granulated carbon, which has a filtration capacity of about 1/10 of an activated carbon block cartridge. Furthermore, the time the water spends in contact with the carbon, especially with small faucet-mounted devices, is too short to provide efficient filtration.
See also our overview of filter types: Filter comparison
A TDS tester is a tool that can measure the amount of dissolved solids in water, including minerals and salts.
A TDS tester is often used by some companies as an indicator of water quality, which is misleading, as a TDS tester cannot measure impurities in the water. Therefore, a TDS tester cannot tell you whether your drinking water is healthy or not; it only shows how conductive the water is.
For example, an activated carbon filter does not filter out salts and healthy minerals from the water, which will result in a high PPM reading with a TDS meter. However, these minerals are something you definitely do not want to miss in your drinking water. This is likely also the reason why companies selling reverse osmosis water filtration systems swear by TDS meters, as reverse osmosis filters out all the healthy minerals from the water, thereby giving a low PPM reading. However, a low PPM value does not mean that the water does not potentially contain viruses, bacteria, pesticides, PFAS, medication residues, microplastics, etc., as none of this can be measured with a TDS tester.
A TDS tester can make some sense in areas with potentially very dirty water, and readings of 1500+ PPM can indicate that you should not use the water for daily consumption.
However, if you want to test your water for impurities, the only reliable solution is to send a water sample to an approved institute and have it tested specifically for the impurities you want more information about.
The different cartridges can filter between 5.000 and up to 36.000 litres. Actually some of them can filter up to 100.000 litres and still perform well, but we do advise to follow the recommended changing intervals to avoid any chance of bacterial buildup.
In certain areas and even locally in some streets and buildings the water and/ or piping can be in a state where much more material and general dirt, rust and other substances are added to the water, which can fill up the cartridge early and therefore begin to perform poorly. Under souch circumstances the cartridge will need to be replaced earlier.
You will find many shower water filters with 10 or 15 stage filtration and claims about benefits and filtration abilities that sound almost too good to be true. A shower water filter has however a limit to how big it can actually be and still be practical and fit with most shower setups, meaning the amount of material that can be used for each filter layer is limited. Therefore a 15 stage shower water filter will have a very limited amount of material in each layer. This might not matter much with most of the layers as they do not make any difference and just make it sound "amazing", but it also means the materials that will actually make a difference, is very limited.
In all efficient shower filters you will find a high amount of calcium sulfite, KDF 55 and coconut based active carbon. Those are the ones to look out for if you want your water filtered efficiently. Some will however cut corners and use cheaper KDF and traditional wood based carbon, which is not as effective. So make sure when choosing your next shower water filter you know what materials are used and do not be impressed with claims that the high number of layers actually does anything better for your skin, hair and most importantly, your health.