The manufacturer of Dr. T's Mosquito Repelling Granules does state not to water area for 48 hours after application, as this could certainly reduce the effectivity of the active ingredients, which means you may need to reapply the product if the treatment are gets wet within that timeframe. For specific product questions, you can refer to the product label, or contact the manufacturer directly at (855) 542-8242, or via their website's contact page here.