I have 2- 7 gallon jugs filled with tap water. I rotate the water every 4-5 months. Is this okay in terms of using it to drink in case of an emergency? I keep them in my garage out of the sun. Do I need to use purification drops? Also, I have a Katadyn hiker pro... I'm thinking it's useful for hiking/outdoor events but I'm considering getting the larger one that supports 13,000 gallons because of the simplicity of the filter and larger amounts water it can purify in a real emergency. Suggestions? I'm sure I'll have many questions in the near future as I'm starting to gather a decent amount of preparedness/emergency gear. Thanks for your help and guidance!