Calibrating your BWT Filter – Pro Coffee Gear

Calibrating your BWT Filter

Getting the best coffee requires having the best water possible

Owning an amazing espresso machine is great but having the best basis for them as top quality water is a must to get the best flavours and aromas of your delicious coffee, and take care of your equipment as well.

BWT filter cartridges can offer the best water for use in professional espresso machines. Let's get to know a little bit more about them...


About your filter. Your filter is made up of 4 components:

  • A particulate filter which captures tiny impurities.
  • A carbon filter which removes chlorine and chloramine.
  • A softener which exchanges hard minerals like calcium and magnesium for soft ions like hydrogen and sodium. The Bestmax Premium also exchanges these hard ions for a patented non-scale forming magnesium to enhance taste.
  • A weak acid resin (WAC) which reduces alkalinity and PH. High alkalinity is a catalyst for scale formation. The more alkaline water is the more quickly it will deposit scale.

This filter should work for most users, however, in rare instances Reverse Osmosis may be necessary if the following is true:

  • The location has extremely high alkalinity or hardness: The water may be outside the setting limits of this filter.
  • The location has 150ppm+ choride levels with a machine that has copper boilers (impacts taste) or 40ppm+ chloride levels with a machine that has steel boilers (causes pitting corrosion). Only RO filtration can materially reduce chloride levels in water.
  • User has very high-volume requirements: RO may be cheaper in the long run.
  • User has very specific TDS or taste requirements: Ion exchange (softening) doesn’t reduce TDS, it simply replaces hard minerals with soft minerals. Users with precise water requirements will not have the same level of control as they would with an RO unit.

About the test strips: We’ve provided HACH lab grade test strips for calibrating your filter. One is a 5-in-one water quality strip and the other measures chloride. Below we will show how to use these to calibrate your filter.


Calibration directions

1- Initial water test, Chloride: Remove the Quantab chloride test strip from the package and test your water per the following directions:

- Remove a titrator from bottle and replace cap immediately.
- Insert lower end of titrator into solution. Do not allow solution to reach yellow completion band at top of titrator.
- Allow solution to completely saturate wich of titrator. Reaction is complete when yellow band turns dark.
- Note where the tip of the white chloride peak falls on numbered Quantab scale. This represents the Quantab unit value.
- Refer to the table below to convert Quantab units into salt concentration.


  • If your machine has a copper boiler, anything below 3.6 (~150ppm) is acceptable as 150ppm is the level at which chlorides begin to impact taste
  • If your machine has a steel boiler, anything below 2.0 (40ppm) is acceptable. Chlorides cause pitting corrosion in steel boilers, so higher chlorides will reduce lifespan of boilers.

This filter will modestly reduce chlorides, so you may try and retest post-filter if you have a boarder-line result. If your result is substantially too high, then you need an RO unit.


2- Initial water test: setting filter based on hardness. You’ll test your water to see which filter setting is best between 0-3, where zero is fully filtered and 3 is most blended. During the first test, we’re just concerned about measuring hardness. Pour water from the filter into a cup. Dip the 5-in-1 test strip in the water for one second, matching the color of the middle pad (3rd from top) to the below image.


Set blend setting: Take your result and choose a “Blend” setting on the below chart which corresponds with your PPM result. For example 214ppm correspond to a blend setting of “2”:

Blend settings

Filter lifespan: follow the row from your ppm CaCO3 result on the left side and match with your filter size on the right side to determine your filter lifespan. Your filter lifespan will be ~1 year or the lifespan on the chart, whichever comes first.

3- Filter Install: Now you can begin installing your filter. Place the filter head on your filter. You will notice that there are a range of numbers on the filter head. These correspond to blend settings which allow water to bypass the softening and WAC resin. Set based on your above results.


4- Filter purge: Once you install the filter, flush the filter by using the purge valve on the premium filter head (white) or through the machine facing line on the regular head (blue). Purge about 1 gallon of water.


5- Confirm filter settings: Test the water coming out of the filter to ensure the settings are correct. Pay close attention to alkalinity as that’s the most common reason for needing to adjust the filter.

Pour water from the filter into a cup. Dip the 5-in-1 test strip in the water for one second. Wait 3 seconds and compare the results to the below (top of strip down):

Chlorine: These should be at or near zero or white.

Hardness: Set between 50-175ppm

Alkalinity: Set between 40-80ppm

Hardness and Alkalinity

Special note: Pay close attention to alkalinity as small differences can mean a lot in terms of scale formation or corrosion. Alkalinity below 40 begins to cause boiler corrosion and alkalinity above 70 begins to increase scale formation, even when hardness is relatively low. See fancy SCA Water Quality handbook below.

PH: This is highly correlated to Alkalinity and should be between 6-8.

Source: SCA Water Standards. See chart below:



6- Adjusting water settings: Hardness Alkalinity or PH are outside of the correct range, decrease blend number to reduce hardness, alkalinity and PH or increase the blend number to increase hardness, alkalinity and PH.

If you have any questions or need assistance to know exactly what you need, send us an email or give us a call.


Phone: +1 (512) 240-2455

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