Installing Alb Filter: sequence, fitting and cartridge change

Mechanically, there are only 2 families. The Duo screws directly onto the kitchen tap with an M22x1 female thread. Element, Mobil and Travel, on the other hand, are based on the same housing, with a female thread at the top and a male thread at the bottom, both 1/2 inch in size. The Fusion couples 2 of these housings via a connecting module called Connect.

Space is a common reason for ordering the wrong product. An Element housing measures 69 mm in width and 122 mm in height. At 227 mm, the Fusion is almost twice as tall because 2 housings sit one above the other. Measure the under-sink cabinet before you buy.

In the direction of flow, the Active cartridge comes before the Nano cartridge. If there is also a Protect pre-filter in the system, it goes first. The complete order is: Protect with 40 µm porosity, then Active, then Nano.

Alb Filter makes this sequence mandatory in the Fusion manual and gives the reason two lines further down. When the Active cartridge is flushed for the first time, fine carbon particles come loose as a result of the production process. If the Nano cartridge is already in the housing at that point, the carbon dust shortens its service life. It is therefore only inserted after the Active cartridge has been activated.

The order follows a filtering logic: coarse before chemical before microbiological. The Protect retains sand, rust and sediment. The Active cartridge made of sintered activated carbon binds dissolved substances. The Nano cartridge made of plastic hollow fibres forms the final barrier and, according to the manufacturer, retains germs and bacteria down to a size of 0.1 µm.

The flow rate of the Fusion is determined by the Active cartridge. At 3 bar it lets through 7 litres per minute, whereas the Nano cartridge lets through 11 litres. The slower component sets the pace.

The Mobil filters the water while the tank is being filled from outside, whereas the Travel is permanently installed after the water tank. Both deliver 5 to 11 litres per minute at 2 to 3 bar and have 1/2-inch connections.

The Mobil set includes hose connectors, a tap connector and an appliance connector from the Geka brand, all certified by the Deutscher Verein des Gas- und Wasserfaches (DVGW, German Technical and Scientific Association for Gas and Water). It also comes with a 30 cm Quarzflex drinking water hose, approved in accordance with DVGW and the guideline for plastics in contact with drinking water (KTW). The filter hangs between the water source and the tank filler neck.

On the Travel, installation follows a different sequence. First the housing is installed, then the Active cartridge is activated, then the pump is switched off and the pressure is released via the open tap. Only then does the Nano cartridge go into the second housing.

One issue only affects camping use. Water from lakes, rivers or wells contains sediments which, according to the manufacturer, severely impair filter performance. For this, the manufacturer recommends the Protect as a pre-filter. If the vehicle is left standing for a longer period, the cartridges should be taken out of the housing and left to dry with the nose pointing upwards. Do not store them in the fridge, do not put them in rice, do not keep them in closed containers and do not freeze them. The step-by-step instructions can be found on the Mobil and Travel installation page, and the background in the guide to water treatment in the motorhome.

A new Active cartridge is activated by letting water run through the filter for 20 seconds. Direct the flushing water into the drain. Activated carbon dust from the production process may come loose and make the water slightly cloudy.

The cartridge is press-fitted with 2 O-rings in the lower end cap. Press the new cartridge into the holder with a gentle twisting motion and screw the cap onto the filter body hand-tight. On the Fusion, the Active cartridge sits in the Connect connection module instead.

An additional rule applies to the Fusion. The Nano cartridge must not be in the housing during activation. It is only inserted after flushing. Then check the entire system for leaks.

The Active cartridge lasts 4 months or 3,000 litres, the Nano cartridge 6 months or 5,000 litres. Both figures are stated as such in the manufacturer's manual. For the number of months, Alb Filter assumes consumption of around 150 litres per week.

Active and Active Plus+ are pollutant filters; the Nano cartridge is a germ filter. Three situations require an earlier change for all of them. Firstly, a visibly reduced water flow. Secondly, a noticeable change in water quality. Thirdly, a period of non-use of more than 6 weeks, for example after a holiday or after the winter break in the motorhome. According to the manual, an early change is not a defect of the cartridge but an indication of increased fine particles and pollutants in the unfiltered water.

Besides the cartridge, the housing also needs attention. Depending on the water quality, deposits build up inside and are removed with a cloth. The manufacturer specifies 2 months for this for the Duo and Element and 3 weeks for the Mobil and Travel. To tackle limescale, the manuals mention diluted phosphoric acid or sulphamic acid, as found in descalers for coffee machines. When changing the cartridge, apply a food-grade lubricant to the threads so that the screw connections keep turning easily.

For hygiene reasons, a filter element must be changed at least every 6 months. The 6-month deadline comes from DIN 1988 and applies to the mechanical filter at the point where the water enters the building. Alb Filter applies it to its own cartridges and specifies 4 to 6 months.

Both deadlines have the same reason. A water filter is a surface on which residues collect, and residues are food. Asked whether activated carbon can become contaminated with germs, Alb Filter's own FAQ answers with one word: yes.

The Verbandsgemeindewerke Selters (the Selters municipal utility) describes the finding from practical experience. Its information sheet on domestic plumbing states that water quality checks had increasingly found coliform germs because of defects in the domestic plumbing. As a cause of excessive germ counts, the information sheet names in particular frequently installed water filters that are poorly maintained. Before changing the cartridge, it recommends disinfecting your hands to keep germs from outside away.

The Umweltbundesamt (German Environment Agency) goes further in its recommendation on the risks of post-treating drinking water. It starts with one condition: a drinking water installation that is planned, built and operated in accordance with the generally recognised rules of technology. According to the Umweltbundesamt, there is no need for post-treatment in such a system for health and hygiene reasons. The recommendation explicitly rejects installing additional devices purely as a precaution. One reason it gives is the growth of microorganisms and pathogens in the filters. The recommendation dates from 15 December 2021. It therefore refers to the Drinking Water Ordinance as it stood before the 2023 revision.

We are recording this position here even though it argues against our own product. It does not change the decision for or against a filter. But it does define the obligation that comes with installing one. A cartridge left in place for too long makes the water worse instead of better. The replacement interval is therefore not a buying recommendation but the condition under which a filter remains justifiable at all.

§ 10 no. 1 of the Drinking Water Ordinance (Trinkwasserverordnung) requires compliance with the requirements at the outlet of the drinking water draw-off points. That is exactly where a tap filter sits. The installation location therefore determines more than just the look.

The Ordinance draws a line. Under § 1(2) no. 4, it does not apply to water downstream of the necessary safety device of an appliance connected at the end of the line. This presupposes that, according to the generally recognised rules of technology, the appliance is outside the drinking water installation. § 10 no. 2 then moves the point of compliance to the safety device itself. The note in the Duo manual never to operate the water filter on the drinking water network without a system separator points in the same direction.

Whether a particular device is part of the drinking water installation according to the recognised rules remains a technical classification. We are not making it here. The consequence is the same in both cases: the operator, not the water supplier, is responsible for the water quality downstream of the filter.

§ 13 applies to installation within the drinking water installation. Systems must be planned, constructed and operated at least in accordance with the generally recognised rules of technology. Under § 14 no. 3, the materials used must not promote the growth of microorganisms.

Private households are not required to notify the public health office (Gesundheitsamt). § 11(1) is aimed at operators of central, decentralised and private water supply systems. It also covers building water supply systems if the drinking water is provided as part of a public activity. Anyone installing a filter in a rented or commercially used building should check this boundary.

The costliest mistake concerns non-pressurised water heaters, and all 3 manuals mention it. Upstream of the cartridge, pressure builds up to roughly mains pressure and only dissipates slowly. According to the manufacturer, this can damage a water heater that is not pressure-resistant. With a non-pressurised water heater, the connection should therefore be made by a plumber.

• Hot water instead of cold water. Drinking water cartridges are designed for cold water; the limit is 45 degrees.
• Tap with a pull-out spray. The Duo is not designed for this type of tap.
• No leak-stop valve under the sink. Without a floor drain, water from a leaking fitting runs into the base cabinet.
• Nano cartridge inserted too early. Carbon dust from the Active cartridge shortens its service life.
• Frost. All housings and cartridges must be protected from frost; in a motorhome, this applies to the winter break.
• Cross-threaded connections. For the Fusion, the manual expressly warns against fittings screwed on at an angle.

The manuals for the Element, Fusion, Mobil and Travel state that installation work may only be carried out by a trained specialist.

The Umweltbundesamt (German Environment Agency) is more explicit. Work on drinking water installations is not a job for DIY enthusiasts, it says, and should only be carried out by specialist firms. At the tap, this makes no difference, as all you do there is screw onto a thread. Under the sink and in a vehicle, the situation is different. If you have any questions about installation, our customer service team will be happy to help.