Changing water filters - how often, and what is the risk?

Again and again, there are ambiguities as to how often water filters should be changed. How this affects the individual filters and what risk can exist if you change too late is therefore explained in detail here.

Types of filters

Water filters are available in different versions:

  • as a house water filter
  • as filter systems to improve drinking water, especially through activated carbon filters
  • special filter systems (such as reverse osmosis systems, ion exchangers or similar)

Depending on the design, the maintenance or replacement intervals are different.

Simple filters at the house connection

They are only for particle filtration, and are therefore very simple. A visual inspection of the filter every 2 months is sufficient. For visible soiling it should be replaced, for safety's sake at least once a quarter.

Backwashable filters make replacement unnecessary. The rinse completely cleans the filter. Only the maintenance intervals according to the manufacturer's specifications apply.

For additional filters (such as activated carbon), the replacement instructions and maintenance intervals apply to the respective filter type.

Fiter systems with activated carbon

Activated carbon filters, which can be found, for example, in can filters, have to be exchanged very frequently. There is a high risk of microbial contamination of the filter.

Depending on the degree of contamination of the water, the filter can clog up very quickly and thus become ineffective. An influence on the pollution of the water filter also has the water hardness. The harder the water, the more often it has to be exchanged.

Many devices also have a built-in filter change indicator. The information on this display must be observed. In addition, there is also for each filter manufacturer information when to be replaced. They are also important to note in order to exclude a risk.

Ion exchangers and reverse osmosis systems

Ion exchangers must be regenerated at regular intervals. This is done by rinsing with a regeneration solution. The performance of exchange resins is different, so regeneration after different periods of time is required.

Even with reverse osmosis systems, the maintenance intervals, such as changing the pre-filter and replacing the membranes, must be strictly observed. It can also come here to a so-called reverse germination.


The greatest risk associated with insufficient change is the contamination and breakdown of accumulated, filtered substances. This poses a serious health risk.

Tips & Tricks

When purchasing reverse osmosis equipment, always consider the maintenance costs involved. It can be very high in some systems.

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