i did not know it could be so hard. i first tried to insert it gently but given my lack of succes i started toi get impatient and tried it harder, just to realize that i was hurting myself. then i thought that some lubrication could help. i got it wet and this time it was a lot easier, it went smoothly all the waay in. iIt felt so good. I'm writing just in case it may be of any help if one of you guys ever face a similar situation trying to get the tube of your camelback through the termal housing after cleaning it.