You dont have to use water. That is just a waste if you are on the trail. Just run your hand around your wheel on the inside and if your relativly lucky you will stab your self with a thorn. Then figure out where it is on the tube. Also you can just inflate the tube and turn it slowly near your face and you will hear/feel the air comming out. If it is a really small puncture then yes you will need to use water. You are giving this to none bikers though so they wont see the other problems in it.