The water filter holder started displaying some sort of self-check message all the time.
Perhaps a day or so later the battery was drained so I decided to take a look what was going on. Opening it was easy once you figured out how it was put together.
However it seems like moisture have gotten into the electronics.
The device lasted about 4 years of constant use everyday.

It was interesting to see that it measured the water going to the filter with an impeller and a hall effect sensor. I was skeptical and thought the device just used an optical sensor to just see if there was water flowing or not. It was nice to see a properly designed product that did what it was designed for. Hats off for Toray.

The cartridges are not very cheap but they do filter out most of the chemicals used for water purification + others. The water from the water supply is low in minerals anyway. It's not so good water for drinking or bathing.

Removing the sealant, drying and resealing the circuit board, might be possible but it's not worth my time. Since the device is just a convenience thing and not really necessary. I've decided to just take the battery out and use like that for now. Just have to remember to change the filter every 3 months or so like the ones without a meter.

The question is would it have been cheaper to have used a cartridge holder without the meter and display in the first place?