I'm not sure about what sort of setup you have, but it isn't necessary to leave them overnight and wouldn't be oractical at my store. For most of our pumps, they're left to dry fir a while but we have most if them back out in either new product or a backup for the next day. We usually leave the chai and hot bar mocha pumps in the back because we usually don't double those up for the same expiration date or we waste product.