Long-term testing: what matters is what happens after months of use.
A new water filter can deliver good laboratory results. We are interested in a more challenging question:
What does it look like after months? And after a year?
That is why we do not examine SAN-MAXI only at the start of its service life. We monitor selected systems over an extended period and have the water quality tested repeatedly by independent laboratories.
We have deliberately created distance between ourselves and the measurements: SANSEI does not take the water samples or send them to the laboratory – our customers do this independently. We then receive the laboratory results.
This gives us measurements from real-life conditions, rather than ideal conditions created specifically for a test.
Over a year. The same cartridge. Six laboratory analyses.
This system’s SAN-MAXI was installed on 10 July 2025 The sample scheduled immediately after installation was accidentally not sent to the laboratory by the plumber.
The first documented analysis was therefore carried out on 19 August 2025 – around 40 days after commissioning. Testing then continued:
| Date | Time since installation | Aerobic mesophilic microorganisms | Test report |
|---|---|---|---|
| 19 August 2025 | approx. 40 days | 7 CFU/ml | |
| 30 October 2025 | approx. 112 days | 6 CFU/ml | |
| 6 January 2026 | approx. 180 days | 8 CFU/ml | |
| 17 March 2026 | approx. 250 days | 1 CFU/ml | |
| 21 May 2026 | approx. 315 days | 2 CFU/ml | |
| 24 July 2026 | approx. 379 days | < 1 CFU/ml |
7 → 6 → 8 → 1 → 2 → < 1 CFU/ml
More than one year after installation, and beyond the recommended service life of the filter cartridge, this series of measurements shows no increase in the measured aerobic mesophilic microorganism count downstream of SAN-MAXI.
The lowest value in the entire series was recorded in the final analysis: < 1 CFU/ml after around 379 days.
There is another aspect that makes this long-term test particularly interesting to us:
This cartridge was not backwashed once.
That explicitly does not reflect our recommendation. We recommend regular backwashing to flush retained deposits out of the cartridge and extend its maintenance interval.
However, the fact that this system was not backwashed at any point during the documented period makes the observed development of the microorganism counts even more interesting to us.
We do not only measure when the filter is new.
Water filters are often presented with laboratory values for filter performance. What interests us much more is how they develop under real conditions over a period of months.
That is when we see what happens inside the filter over the long term.
So far, we have found very few publicly documented long-term measurements for domestic water filters under real operating conditions. That is why we are continuing these measurements: transparent, repeated and carried out on systems in real use at our customers’ homes.
Not because we distrust our filters.
But because we want to know whether they will be just as convincing tomorrow as they are today.
An important note about these measurements
This series documents the aerobic mesophilic microorganism count in the water downstream of this specific SAN-MAXI system at the respective sampling times.
As the baseline sample scheduled during installation was not sent to the laboratory, this series of measurements cannot be used to calculate a percentage reduction in the microorganism load compared with the source water .
The results also cannot be transferred directly to every installation, as water quality, usage, temperature, stagnation times and other operating conditions may vary.
What this series documents is the development of the measured microorganism count downstream of the same SAN-MAXI cartridge over more than a year of real-world operation.
We are carrying on.
Six analyses are not an endpoint for us. With further systems and further measurements, we want to document step by step how SAN-MAXI performs throughout its entire service life under real conditions.
On our future laboratory page, we will bring together the measurement series, background information and the associated independent laboratory reports transparently.
