The purpose of this article is to try to provide a brief overview of the important specifics regarding in-the-field water filtering.
When talking about water filters, a micron is the average size of opening between filter media. The larger the number, the larger the opening between media, and thus the larger the particle of matter that can get through the filter.
In general, the smaller the number the better, but there is a tradeoff between micron size and filtering speed. Also, if the water has a lot of sediment, then the smaller the micron rating, the faster the filter will clog but the more it will filter out. ( Purchasing Tip: Look for filters that have sediment pre-filters, like the MSR MiniWorks EX or Katadyn Hiker Pro)
So what micron rating should you look for?
Lets look at the types of things you want your water filter to remove:
Bacteria range in size from 0.2 microns to 2 microns in width or diameter and from 1 to 10 microns in length (for non-spherical specie) A 1 micron filter will remove mostbacteria.
Viruses range in size from .005 – 0.3 microns.The lifesaver Jerrycan will filter out viruses to 0.015 microns in size. This includes all of the most common viruses found in water.
- Heavy Metals
No backpacking water filter is going to remove significant amounts of Heavy Metals. Both Katadyn and MSR are ambiguous about how much, or which, heavy metals their filters might remove.
As with heavy-metals, no backpacking water filter is going to remove a significant amount of chemicals from the water. Neither MSR nor Katadyn will commit to what they will remove, however both companies indicate that their filters will remove some chemicals.MSR Water Treatment and Hydration FAQ
Carbon Filters -vs- Ceramic Filters
As much as I would like to go into details on the differences between ceramic and carbon water filters, the truth is that it is just not that simple. There are many types of both filters. That said, here is a basic rundown of the pros and cons between the Ceramic filter with carbon core used by MSR Miniworks EX, and the carbon filter used by Katadyn Hiker Pro:
|Katadyn Carbon||300 Gallons||0.2 Microns||Lighter, more durable (won’t crack), higher flow rate than ceramic||Filter replacement Should be cheaper, but isn’t (is actually nearly 40% more), reduced efficiency over time, not field serviceable(1)|
|MSR Ceramic||500+ Gallons||0.2 Microns||Longer life than carbon, field serviceable||May crack if dropped or frozen, slower flow rate than carbon|
1 The Katadyn Hiker Pro advertises as having a ‘field cleanable filter protector screen’, but this is in no way equivalent to being able to clean and sanitize a ceramic filter in the field.
So which microfilter do I use? I chose the MSR MiniWorks EX over the Katadyn Hiker Pro. There are pros and cons to each unit, and people on both sides that swear by their choice. Ultimately, I chose the MSR because the filter is easily removable, cheaper to replace, lasts longer, and easily cleaned and sanitized.