I am keeping this on hand as a backup.   Woops I guess it was the CDC. A Guide to Drinking Water Treatment and Sanitation for Backcountry & Travel Use https://www.cdc.gov/healthywater/pdf/drinking/Backcountry_Water_Treatment.pdf The temperature listings http://www.polarpurewater.com/instructions/ http://amzn.to/2lqBSsY Polar Pure Iodine Water Filter Purifier Sterilizes 2,000 Quarts Katadyn Hiker Pro Microfilter http://amzn.to/2m2FMF9 http://amzn.to/2lSCWGW Vipe Digital LCD Aquarium Thermometer Fish Tank Water Terrarium Temperature