Just a Drop creates a seal directly on the waters surface, blocking odours from escaping, until they are flushed away, while leaving behind a, fresh scent.Is it safe for my toilet? How long does it last? Just A Drop A 15 mL bottle of Just a Drop has enough liquid to last for 400 uses or around 90 days.Is it safe for my toilet? It's more safe than anything you could find in the market.