If you choose not to use chemicals in your pool, the water should be drained after use within 24 hours. Although this means refilling the pool with fresh water every day you use it, it's the best way to prevent infection and waterborne diseases from forming. Using chlorine tablets or small amounts of bleach in your pool to keep the water safer isn't a good idea either. It's too tricky to determine the right dose in order for it to be effective, especially if there are multiple children using the pool. To keep your pool as safe as it can be, it's best to stick to emptying and washing it out after every use.