I have also had giardia. One and one half years later, I was rid of it. Even so, I could be a carrier. I do not share drinking or eating utensils, or containers. Giardia is bad. The drug treatment is bad. Be careful.

There are a number of reasonably convenient means of having good drinking water:

• Carry Water: I have Platypus brand Holster 1-liter flat water carriers for drinking water. The carriers are insulated, to an extent. They have a comfortable shoulder strap I don't mind. The drinking water is at hand. I have two. Both start out, having fresh drinking water. Then, one becomes my water treatment receptacle. This is a minimum. If I am going out for more than one day and if I plan an overnight, of course, I have a larger Platypus Water Tank, for carrying water and for water for cooking.


• Treat water: The Sawyer brand filteration products are here.

  I have a Sawyer in-line water filter, because I can use it in towns on a thru-hike or near the trailhead, plus I can use it with my 1L or 2+L Platy Bottles or plusBottle with either the Platypus Quick-Disconnect Kit or Platypus Shutoff Valve.

  It should be noted, the Platypus Cleanstream Filter Cartridge is available separately, either for replacement or to assemble your own gravity filter kit using the smaller 1L or 2+L Platy Bottles or plusBottle.

  The 4 Liter Platypus "Clean Stream" Gravity Microfilter complete system is also available.

  I "prefilter" with a cloth or one of the .4 micron prefilters available for widemouth water bottles, which I "dunk" below the surface using a hiking pole.

  The inline water filter is suspended between the Platypus containers, for gravity feed. I do this during lunch break, or at the end of the day. I treat the water, inside the container by adding the right amount, and no more, of McNett AquaMira 2 part water treatment drops in plastic Microdrop dropper bottles. I wait for the amount of time for the water temperature. This is why I have two drinking water containers. One is ready for drinking, while the other is getting ready for drinking. I have the larger Platypus water container full overnight, and ready for drinking and using the next morning.

• The 4 Liter MSR Autoflow Microfilter has a top-opening water bag, much like the storage bags for kayaking. It is possible to rinse out this bag entirely.

I do not recommend iodine water treatments. No one should have iodine, very often.
I have seen hikers, using the Katadyn Exstream XR Purifier water bottle. If ultralight is for you, and if you do not mind a miniscule trace of iodine, I would use this product, by using a coffee filter or a cloth as an additional prefilter.

I do recommend water filtration, if the standard is 2 microns or less. However, I don't like to carry either the Katadyn Pocket or SweetWater Guardian water filters I have seen in use: they are heavier and bulkier than the system I prefer to use. If you always like to carry a rucksack, or a small pack, a water filter may be your choice.

My international adventure travel trekking friends insist the Katadyn Pocket water filter kept them healthy.

The SteriPEN has gained popularity, because it weights 4 oz. and 1 liter of water is ready in 90 seconds. However, the water must be clear. This means, cloudy water (silt, glacial runoff, or algae) will not be purified. Many people have a Steripen, for clear water, and have a backup system for everything else.