It's a bladder tank. When you open a faucet with the pump off, it will discharge all its contents until the bladder touches the inlet port. The only possible place for water to collect would be the inlet piping. I sloped the inlet piping toward the cold water line to the vanity faucet so that when I open the low point drains, all the water will run out.
2006 23B Hybrid with 10k round bar WDH
2011 F150 4x4 SCREW Ecoboost, Max Tow, Integrated TBC, 3.73 LS axle, Firestone Ride Rite airbags.