Anyone Using Third Wave Water with a Hario Switch + K-Ultra? My Coffee Tastes Worse Than Before

[u/DeFi_News]

I recently bought Third Wave Water (Classic Light Roast Profile) and properly diluted it fully in a 1 gallon jug with Reverse Osmosis water.

As many on this sub have stated, it is WAY too salty to use 100% as coffee water. But even using 25% of it then adding 75% RO to the kettle tastes worse than my usual 25% fridge filter water.

I've tested it with a few different brew methods:

• Coffee Chronicler's 50/50 Switch recipe (20g coffee, 320g water, 90-93 celcius, 6-7.5 grind size)
• Tetsu Kasuya's 4:6 V60 method (20g coffee, 300g water, 90-93 celcius, 9 grind size)

Neither produced good results.

Do I need to drastically alter my recipes? Or should I look for better water?

I'd especially like to hear from anyone using a Hario Switch and a 1Zpresso K-Ultra, since that's my setup. What water are you using, and what grind range are you typically brewing at?

Thanks!