Friday, June 2, 2017

Water Filter vs Water Purifier

A few buddies of mine and me are in the process of planning a back country fishing trip with Kashabowie Outposts in Ontario, Canada. Part of the planning process includes providing potable water for four grown men for a week. Yes it is true we will be fishing on a very remote lake in the boreal forest of Canada where human interaction is  minimal but that doesn't stop the bacteria from infiltrating these pristine lakes. 

In doing research for some sort of water filter or purifier I came across an article written on a backpacking website that sells water filters and purifiers. MSR - Mountain Safety Research ( explains rather simply the differences between water filters and purifiers. 

Quite simply, it is the difference in protection they provide. "A water filter is designed to remove waterborne protozoa and bacteria, but not viruses. A water purifier is designed to combat all three classes of microbes, including viruses." 

Viruses are much smaller and simply slip through most filters designed for bacteria. In order to remove the viruses traditionally we needed to use ultraviolet light, purification tablets or boiling the water for five minutes. This would either kill the viruses or scramble their DNA and render them ineffective. However some new mechanical pump filters are able to remove viruses also. 

When to choose a filter over a purifier. When traveling in the US and Canada a filter is all that is recommended. These filters will remove all traces of protozoa like cryptosporidium and Giardia, and bacteria such as E-Coli and salmonella. 

Waterborne viruses that we are concerned with are largely transferred by human waste. Making the use of a purifier where human traffic is minimal not necessary. However it is very important that your filter is designed to remove these protozoa and bacteria. Some filters are designed only to remove unpleasant taste and not the contaminants. 

The EPA recommends filters to remove contaminants down to 0.2 microns. 

If you are traveling to third world countries or concerned about the purity of the water and are unsure of the quality, err on the side of the purifier. It is important to remember that boiling and ultraviolet light and tablets do not remove sediment from the water. In these cases it is recommended that you purify and filter the water. A personal preference is to filter first and remove all sediment before purifying the water. 

For our trip we are going to use the filter system. Research is showing that there are several that fit the bill. We are opting for the gravity flow filter systems. It is simple. We fill a 4 liter bag with dirty water and hang it higher than the clean water bag. The dirty water flows through a filter removing the contaminants and deposits the clean water into the lower bag. We are looking at two different models, the Platypus Gravity Works, ( the MSR Gravity Flow Filter.  (

We are leaning towards the Platypus ( because it is a 4 liter system while the MSR is a 2 liter system. Either way, it is important to understand the difference between a filtration system and a purifier. There is no need to purchase a purifier when a filter will do the job. 

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