Trust me. One case of beaver fever and there will be no such thing as too cautious. Very common in our neck of the woods actually. I admit, I wasn't in Canada at the time I was struck down but it was a lesson well learned about having someone else prep drinking water. I only drink water I prepare myself nowadays.

It was a steripen that was used BTW. I don't know if it was user error or malfunction. Maybe the water was too cloudy and didn't have time to be fully zapped before being consumed. I don't trust them anymore regardless. Second time was using one of those useless purification "straws"

Unless I see the water boiling like mad or it tastes like strong iodine I don't get a warm fuzzy feeling. Thus the reason for posing the questions. Now I must admit, water being forced thru ceramic comes out really clean looking. I guess if I am posting from the toilet in a few weeks it can be safely assumed I was no good at working an MSR filter either.

I don't know about Calgary, but up here north of Edmonton the water is more like a scum right now.(around the accessible edge anyway) The north sask river smells and tastes like fuel, and you couldn't pay me enough to use the snow runoff in some areas do to all the chip bags and garbage collected in the water.

In some very sandy water, like the Colorado River in the Grand Canyon, it could help to have something wrapping the float to help filter some of the silt. Normally, there is no need for anything, the float has some filtering built in. I have never had it clog on me but that is always a possiblity, with any filter, really. It can easily be cleaned in the field. The clearer the water source the less likely it will clog. Scooping water into a container and letting it settle would be desireable. In that case it may be better to wrap the float with a bandanna or filter the water through a cloth before filtering. The more sand and debris the more likley the filter will clog or at least pump harder.

The standard wide-mouth Nalgene 1L bottles will thread directly on the MSR filter. That is a nice design feature.

I don't know or at least I'm not convinced about most stomach ailments being a water problem. I know we are all careful with filters, bleach, tablets, chlorine dioxide, boiling water, et al. but I think the majority of our "beaver fevers" have little to do with giardia and the like but rather good old e-coli and samonela. I think a good portion of our ailments are either a result of poor food handling and simply poor personal hygiene.

The liberal use of hand/face washing and even alcohol based cleansers would do much to reduce these problems. When you are camping by yourself, you are dealing with your own issues but in a group you may be dealing with others with less than ideal hygiene practices. All it takes is one person to forget to wash up after a bio break. Then everybody grabs into common snacks, meats and cheeses, common utensils, etc. and the potential for spread of bacteria increases. Now, put your food back in the pack and let warm temperatures incubate them.

I've only had one real intestinal problem from camping in my life -- I got the runs. And that was more likely due to not filtering "milky" glacial water more than anything else. Uncomfortable yes, but also a problem because I only had 1 set of underwear so other people on the trail "knew" I had a problem too!

I use an old Katadyn Hiker filter but prior to starting a trip, I check out the filter itself. If there is any question at all about the filter material, I toss it and replace. I have been know to boil and thoroughly dry the filter as well before the trip. Other things like keeping the tubing clean and the hydration bag sanitized, mouthpiece clean, etc. are also good practices.

I second on the coffee filter trick. I hiked in a swampy marshy area that had a ton of algae. After the first round of filter left me with green tinted water, I filtered a second time with the coffee filter and it came cleaner and most of the wierd tast went as well. On that trip it was very warm (30*C, 90% humidity) so I didn't use my stove much. Boiling the water in the evening for a full hydration bladder isn't much fun.

A trick I use is a funnel with 1 or 2 cone shaped coffee filters to pre filter before letting the water settle then refiltering before using Potable Aqua. Hope this helps.

My skin is crawling. You couldn't have known that I'm a germophobe. LOL.

I was exposed to water on Ft. Hood Texas after a week of very heavy rain. We had to drink that water in the field since we were on foot and without any large unit support. There were cattle in the area, lots of cattle waste and the only method to purify water was issued iodine tablets.

Within a few days of returning home I began an alternating bout with diarrhea and vomiting. This lasted about a week before finally letting up slowly. After that trip I bought a water filter. I also learned more about the iodine tablets and found that if they are green they have lost their strength and needed to be replaced. I also lost the tablets in the field, having them stored in the little pocket on the canteen cover (USGI) is almost a guarantee that they will end up falling out somewhere.
I was never sure of the exact ailment, other than it was ugly and I have avoided it since.

For sure, keeping hands and kitchenware clean are important, both at home, on the road and on the trail. I even use hand sanitizer after pumping gas to keep from getting something off that pump handle.

All key points, Hygine while in the field is certainly paramount.

Having a dirtbag in the crew certainly don't help. We have a crude name for what you are describing. I won't mention it here but The common slang is simply "gastro". I'm sure nine out of ten times thats all the problem may be. A couple of days with the runs because someone failed to wash their hands and touched your food is not the same as beaver fever. I mean gastro isn't nice either, but it dosen't even rate on the same scale as giardia. Anyone who travels abroad frequently probably picked up "a case of gastro" at least once from eating in an unclean establishment.

When you do get gardia you will know. Takes a week or two IOT develop in most people. Small exposures may not even get to some folks, I have drank directly from water sources many times in the past and almost had to chew the water to swallow it because of all the floaties. Nothing, not even a good fart. but in one particular case we were out for ten days drinking the water we could find as resupply thinking our equipment was working. After drinking that much sheer volume I guess it finally took hold. Knocked me off my feet for a couple of weeks. Another in the party was tested positive later but did not get nearly as sick. If you do react in a less than desireable manner however, look forward to explosive bloody runs, vomiting, severe cramps with chills/fever/skakes and dizziness for 1-2 weeks (with treatment) Not to mention the horrible smell and the embarrasing tests you need to do to confirm your condition at the hospital.

Sorry for the terifying mental images BTW

Go to any automotive parts store like Napa and see what they have, they genereally have a wide selection of them.

The Miniworks EX is a very good filter. Use a coffee filter on the inlet and the element will last much longer. Also, as previously mentioned, the repair kit and at least one spare element is a good idea. Take special care when cleaning the element because they are very fragile when not in the pump!