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 f

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.