If you have a hydration bladder made by Source (or Deuter, which are re-badged Source hydration bladders), you may have run into an issue with the hose becoming harder and harder to insert into the bladder, or with a leak in the connection.
It is very likely that your problem is with the O-ring at the end of the hose, and that replacing the O-ring will fix the issue. This one:
A #6 O-ring will fit perfectly. This is available at most hardware stores. The dimensions of a #6 O-ring are:
|Dimension||Size (in)||Size (mm)|
|Outer Diameter (OD)||7/16"||11 mm|
|Inner Diameter (ID)||5/16"||8 mm|
|Cross Section (CS)||1/16"||1.5 mm|