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by Arik Devens
Jun 3rd, 2022

Good Carbonation with a Grohe Blue and City Water

I recently purchased a Grohe Blue Chilled & Sparkling 2.0 Faucet and, aside from it being fiendishly complicated to install, I'm very, very, happy with it. It's an absurd luxury, but the ability to have chilled filtered water and sparkling water from the tap is absolutely incredible. Key to that experience is the quality of the water though, and initially we were very disappointed. The sparkling water tasted like someone had heard about carbonation before, but had never actually tried it. That led to a ton of searching for help and I did ultimately find a solution. It was obscure and complicated, and that's my cue to write it up for this blog!

Grohe makes this stuff annoyingly complicated. For one thing, the entire instructions are Ikea-style, with basically no words. For another, there doesn't seem to actually be a manual one can find anywhere. They do include a water hardness test with the faucet, and that's the place to start. If your water is below 7 or so on the dKh scale, like most city water will be, you are going to have a problem. Essentially, your carbonate hardness is just not high enough to grab onto the CO2 and create a satisfying drink.

The solution is to install one or more remineralization filters into the water pipeline. These filters exist because the standard reverse osmosis water filters strip out useful minerals as well as harmful ones. The idea is that you install one of these filters after the RO-system and before your faucet, thus adding back things like magnesium and potassium to your water. I'm honestly not sure how well these things work for that purpose, but they do work for ours. However, in our case, instead of installing it after the system, we want to install it in the middle, so that we can raise our hardness and allow the system to do its job.

Specifically, we want to install it between the Grohe filter and the chiller. That presents a problem, because that part of the setup uses metalic water hoses and not plastic quick connect tubing. All the remineralization filters I could find expect 1/4" quick connect tubing. That means I had to find a way to get from the Grohe hoses to quick connect and back again. An additional problem is that the Grohe system is in metric but I live in the USA where everything is in imperial sizes.

After a ton of trial and error I end up needing two adapters. One is 3/8" female ntp to 1/4" quick connect. The other is 1/4" quick connect to 3/8" male ntp. That allowed me to put the remineralization filter in-between the Grohe filter and the chiller. The result is delicious sparkling water.

I'm leaving out a lot of details, like the different between GHT and NTP, or how 1/2" to 1/2" hoses aren't necessarily the same size on both ends. If you want to hear more, you can listen to the latest episode of my Fun Fact podcast, where I discuss the whole thing. Hopefully this will help someone else figure this stuff out, or at least remind me when it's time to replace a filter.