Hi there! I'm preparing for a backpacking trip to the Grand Canyon. I plan to use the GravityWorks System 4L filter. However, the NPS has been alerting hikers to the presence of Noravirus and is recommending filtration and purification. Do you know if Iodine tablets could be added to the "clean bag" of the Gravity Works System so that water leaving the clean bag is both filtered and purified? Thank you! Anna ... View more