Is it bad to leave drain cleaner overnight?
This product is safe for pipes, and if you have an especially slow drain you can safely let it sit overnight. For fully clogged drains, wait for the drain to clear completely.
How long do you leave Drano in?
For clogged or slow-running drains, apply the product and let it work 15 minutes, then flush with hot water. For tough problems, allow 30 minutes before flushing. Drano® Max Build-Up Remover works over a longer time period to prevent clogged drains. Used regularly, it can help keep your drains flowing freely.