[cproctor]

This project [1] is about replicating various mineral waters at home. They have a spreadsheet with chemical analysis of many different bottled waters, and a calculator where you can get your own tap water analyzed and calculate what to add to go from your tap water to Pellegrino, or your preferred mineral water. I haven't tried it yet, but as soon as we get our home carbonation system up and running, am looking forward to it.

[1] https://khymos.org/2012/01/04/mineral-waters-a-la-carte/

[mrob]

If an approximate match is good enough, you can use "Burton salts". It's a blend of salts sold at homebrewing suppliers, matching the mineral content of water from Burton upon Trent, which is famously good for brewing hoppy ales, and which tastes very similar to San Pellegrino.