100% to 0%
The Rocket Giotto espresso machine at my girl friend's place uses water from a Brita filter. This filter has a timer that counts down from "100%" to zero over a number of weeks but that time span is totally unrelated to the actual use of the filter so it's useless as a reminder to change the filter cartridge for a fresh one.
Unpredictable
I reset the timer a few times before replacing the filter but then I mostly forget how often I have reset it and I take out a new cartridge when I start to feel worried about the water hardness, which is subjective and unpredictable.
Brita themselves suggest replacing it every two months or after every 40 gallons of water taken from the pitcher although local water hardness may vary greatly and thus influence the life span of a filter cartridge. So that's not a great help either.
It would be nice if Brita supplied a test kit to see when the water quality delivered by the filter is deteriorating.
Test kits
This morning after coffee I took out a few test kits that I have:
Water samples
I filled three bowls with water:
All three samples were 16ºC:
These were the results:
![]()
I was a bit surprised that the TH droplet measurements seemed more in proportion to the GH results than parallel the measured KH values.
I did the KH test twice to be sure, the second time using 10ml instead of 5ml so 1ºdH difference was then indicated by two drops of reagent.
Conclusions
Apparently, in these tests at least, a filter that has been used for a while can still be effective in lowering the KH substantially even though the GH (drastically lower at the onset) is already increasing.
The TH droplet technique is equally helpful as the GH to check the current effectiveness of the filter cartridge.
70-140 ppm is said to be "medium hard water" and fine for the espresso machine, so the "old" filter that I just replaced could have been used longer.
Quick and easy test?
The electronic ppm meter is useful and convenient as it shows a significant difference between unfiltered water and a brand new or used-but-okay filter. For instance, if I decide to replace the filter if it reads a ppm above 325, it would still be a long way from the unfiltered water quality.
The Velleman digital pH merely measures a marginal difference between samples and does not separate an old (but still good) filter from tap water, so it is not useful for this cartridge testing.
Also, if I want to take the time to set up a droplet test, just one type of droplet test, either the TH or the GH, would tell me enough.
The GH droplet test is the cheapest. I paid about 6 Euros for it, whereas the digital ppm meter was around 80 Euros (plus I bought special calibration fluid to ensure it is working perfectly in the range that I was testing).
The Rocket Giotto espresso machine at my girl friend's place uses water from a Brita filter. This filter has a timer that counts down from "100%" to zero over a number of weeks but that time span is totally unrelated to the actual use of the filter so it's useless as a reminder to change the filter cartridge for a fresh one.
Unpredictable
I reset the timer a few times before replacing the filter but then I mostly forget how often I have reset it and I take out a new cartridge when I start to feel worried about the water hardness, which is subjective and unpredictable.
Brita themselves suggest replacing it every two months or after every 40 gallons of water taken from the pitcher although local water hardness may vary greatly and thus influence the life span of a filter cartridge. So that's not a great help either.
It would be nice if Brita supplied a test kit to see when the water quality delivered by the filter is deteriorating.
Test kits
This morning after coffee I took out a few test kits that I have:
- HM Digital EC/TDS/TEMP COM-100 water quality tester
- Velleman digital pH meter
- "Raw Water Hardness Reagent" measuring TH from Advantage Chemicals
- Tetra Test GH drop test
- Tetra Test KH drop test
Water samples
I filled three bowls with water:
- Water from the tap, unfiltered
- Water from a used Brita filter
- Water from a brand new Brita filter
All three samples were 16ºC:
 |
| test set up |
These were the results:
I was a bit surprised that the TH droplet measurements seemed more in proportion to the GH results than parallel the measured KH values.
I did the KH test twice to be sure, the second time using 10ml instead of 5ml so 1ºdH difference was then indicated by two drops of reagent.
Conclusions
Apparently, in these tests at least, a filter that has been used for a while can still be effective in lowering the KH substantially even though the GH (drastically lower at the onset) is already increasing.
The TH droplet technique is equally helpful as the GH to check the current effectiveness of the filter cartridge.
70-140 ppm is said to be "medium hard water" and fine for the espresso machine, so the "old" filter that I just replaced could have been used longer.
Quick and easy test?
The electronic ppm meter is useful and convenient as it shows a significant difference between unfiltered water and a brand new or used-but-okay filter. For instance, if I decide to replace the filter if it reads a ppm above 325, it would still be a long way from the unfiltered water quality.
The Velleman digital pH merely measures a marginal difference between samples and does not separate an old (but still good) filter from tap water, so it is not useful for this cartridge testing.
Also, if I want to take the time to set up a droplet test, just one type of droplet test, either the TH or the GH, would tell me enough.
The GH droplet test is the cheapest. I paid about 6 Euros for it, whereas the digital ppm meter was around 80 Euros (plus I bought special calibration fluid to ensure it is working perfectly in the range that I was testing).