To open, pull the slider top sideways from the closed/flared end until removed. Unfold the opening and pull the two sides apart. To close, fold the top molded parts down once and slide the slider top across the length of the folded area to seal. For optimal performance, apply a food-grade silicone lubricant to the slider top.
Before you fill your reservoir, make sure the exit spout is sealed with the Plug-N-Play connector and the Slider top is off. Begin to fill the reservoir with water, but be sure not to overfill (see max fill line indicator). The reservoir was designed to carry both cold and warm water (-20°F up to 170°F). See what we recommend and don't recommend putting in your HydraPak.