They could but you would need an awful lot of them to make a gallon of sanitizer. I believe that the dosage for tablets used to sulfite wine is 1 tablet per gallon or five tablets in a 5 gallon carboy. For K-meta powder, the dosage for 5 gallons is 1/4 teaspoon, so 1/4 teaspoon of powder is roughly equivalent to 5 tablets. If you figure 3 tablespoons per gallon of water for a sanitizer, that is 12 quarter teaspoons or about 60 tablets.