I'm glad you asked, yes, liquid rennet is affected to. Honestly, I've used it, but it is a concern, especially when it is easy enough to get distilled water. I've never used rennet tablets of any kind. I've only used liquid. I have never had an issue of milk not setting. I won't ever consider tablets because there have been dozens of reports on the site from home cheesemakers with issues. Splurge for the good stuff. If you're just making a gallon or two, a bottle, well chilled in the fridge will last you a good long while.