Final answer:
To purify water under field conditions, you should draw water upstream and use 2 iodine tablets in a 2-quart canteen.
Step-by-step explanation:
When purifying water under field conditions, it is advisable to draw water upstream and use iodine tablets to disinfect the water. In a 2-quart canteen of clean water, you will need to put 2 iodine tablets.
Field water purification typically involves the use of chemicals like iodine to kill bacteria and parasites in the water. Iodine tablets are a portable and convenient option for this purpose. One tablet can effectively treat 1 quart or liter of water. Therefore, in a 2-quart canteen, you will need to use 2 tablets to ensure sufficient disinfection.
It's important to follow the instructions provided with the iodine tablets and allow enough contact time for the disinfection process to take place. After adding the tablets, make sure to shake the canteen for around 1 minute and then let it sit for at least 30 minutes before consuming the water.