Saran Wrap on Potable Aqua will be ineffective, the tablets will degrade and be useless very quickly and as Commanche and Maggot noted most likely destroy the kit contents.

All plastics...saran, straws, nalgene vials etc cannot contain iodine vapors and each of these has various abilities to slow the transfer of water vapor which also contributes to the tablet degradation.

I would leave water purification out of a kit this small as the amount of water you could treat is too limited to be of any real use in an emergency. I think you should carry a minimum of enough tablets to treat 2 gallons of water....16 potable aqua tablets, and preferrably much more. A whole bottle of Potable Aqua will only treat 25 L of water (~3 gal), which is the bare minimum I carry.