All of our water heaters are tested at the manufacturer level to ensure safety and quality. If there is residual water in your new product, that would be why. Often it is impossible to completely drain the water out of the piping of the heater. If you have a refurbished (Open Box or Scratch & Dent) model, there most likely will be a little bit of water left in the heater for the very same reason: our technical team tests all OB and S&D water heaters here in the warehouse prior to shipping to be sure they are all in great working condition. No need to worry. Just know that it means your water heater has been thoroughly tested.