Comparing the differences in water filters
What is “Dirty” Water?
Water is considered dirty when it contains one or more of the following:
- Natural Organic Waste
- Organic Chemicals
- Microorganisms (Pathogens)
- Inorganic Chemicals
For Backcountry water treatment, Clean water is defined as being Free of Pathogens
What is a Pathogen?
Pathogens are microscopic disease- causing organisms. They consist of Protozoa, bacteria, viruses, and multicellular parasites.
Pathogenic protozoa are single-cell organisms often transferred through human and animal feces. They are found in all types of water sources and can live for months outside a host. Some require a host to reproduce, but most do not. They can be highly resistant to chemicals but are easily filtered due to their large size. They can also be treated with UV light and heat.
Common protozoa to be aware of include: Giardia and Cryptosporidium
Bacteria are single-cell organisms that can reproduce in water. They are medium in size and can be removed by filters that meet accepted standards for bacterial removal. Bacteria can also be treated with oxidants, UV and heat.
Common bacteria to be aware of include: E. coli, Salmonella and Cholera
Viruses are spread through water but only propagate in living cells, so they need a host to reproduce. They can be difficult to filter due to their small size (though notimpossible). They are sensitive to chemicals, UV treatment and heat. Many areas in first world nations are not concerned about viruses in our water source. It is always recommended to see if areas you intend to use water in are susceptible to viruses in the water.
Common viruses to be aware of include: Hepatitis A, Norwalk and Rotavirus
Larger parasites can sometimes be a problem in unfiltered water or developing regions with very poor sanitation. Their large size makes them easy to remove with even the most basic filter and they are highly susceptible to deactivation by boiling. However, they are resistant to UV and chemicals.
Common parasites to be aware of include: Hookworm and Roundworm
What Water Treatment is Right for you?
This is one of the most common and highly trusted methods of treating water. Water is driven by a hand pump through a matrix that filters out contaminants. The matrix is usually made with ceramics, glass fibers, silica, cellulose or hollow fiber technology. Many units also have a layer of carbon that removes organics that affect taste.
Most effectively remove:
Protozoa, Parasites and Bacteria, most do not remove viruses.
Gravity filters are simple, fast and very easy to use. The filter mechanism is similar to pump filtration: water is forced through a matrix and contaminants are removed. Gravity provides the force to move water through the filter media, so there is no pumping required. The filter is usually hollow fiber technology, but models using glass fiber and other filter media exist.
Most effectively remove: Protozoa, Parasites and Bacteria, most do not remove viruses.
BOTTLE / SQUEEZE / IN-LINE FILTRATION
The advantage of bottle filtration is low cost and complexity – the bottle and filter are contained in one simple unit. Most have limited capacity and flow rate, making them better suited for personal use on short trips. Most of these units clean water using adsorptive media (carbon, coconut shell carbon, etc.), and some models use hollow fiber, glass fiber or paper filters. These systems may come with increased risk of contamination due to their construction.
Some models effectively remove: Protozoa, Parasites and Bacteria, most do not remove viruses. Many of these filters do not remove organisms; it is important to evaluate the technology carefully if organisms are a concern.
UV LIGHT TREATMENT
Ultraviolet light treatments are very lightweight and compact, and are effective against viruses. They are more effective in clear water, so they are not as reliable in the backcountry unless a pre-filter is used. The Steripen can be used in tea colour water and still clean viruses.
Effectively kills or deactivates: Protozoa, Parasites, Bacteria and Viruses
This is by far the lightest and most compact option. Chemical treatments can be effective against protozoa, bacteria and viruses. The down side to chemicals is that they impart taste to the water and their effectiveness is reduced in cloudy water. They also require a waiting period, usually 30 minutes but can be up to 4 hours, before the full effectiveness is reached.
Effectively kills or deactivates: Most protozoa (some do not kill cryptosporidium; read labels carefully), Parasites, Bacteria and Viruses.
It’s easy to see advantages and disadvantages to each of the options listed above. Depending on your needs, a combination of treatment solutions may be appropriate. Carefully selected pairings of filters, chemicals and UV treatments can effectively remove practically any waterborne threat.
Boiling is one of the most effective ways to purify water. Heating water to a rolling boil for one minute (3 minutes above 2000m) will deactivate all pathogens that are a risk to humans. The downside to boiling is that it does not remove chemicals and other inorganics. Boiling also requires a significant amount of fuel. And can leave water undrinkable for a long period of time until cooled.
Effectively removes: Protozoa, Parasites, Bacteria and Viruses.
MECHANICAL PURIFICATION (A.K.A. ULTRA-FILTRATION)
Mechanical purifiers, also known as ultra-fitlers, offer a key advantage: the ease of a microfilter with the additional protection of a water purifier. By definition, a purifier eliminates risk of bacteria, protozoa and viruses. Mechanical purifiers use medical-grade hollow fibers to physically remove the pathogens along with sediment, delivering purified, drinkable water in one efficient step.
Effectively Removes: Protozoa, Parasites, Bacteria and Viruses.
|Filter||Weight||Filter Type||Filter Time||Filter Life||Protozoa||Bacteria||Parasites||Particulate||Chemicals/|
|Guardian||490g||Advanced Hollow Fiber||2.5L/min||10,000+L||yes||yes||yes||yes||no||yes||yes|
|Miniworks||460g||Ceramic with Carbon Core||1L/min||2000L||yes||yes||yes||yes||yes||yes||no|
|Trail Base Kit 2L & 4L||460g||Hollow Fiber||1L/min||1500L||yes||yes||no||yes||no||no||no|
|Trail Shot||140g||Hollow Fiber||1L/ min||2000L||yes||yes||no||yes||no||no||no|
|Gravity Works 4L & 6L||330g (4L)||Hollow Fiber||1.75L/min||1500L||yes||yes||no||yes||no||no||no|
|HikerPro||312g||Glass Fiber w Carbon Core||1L/min||1150L||yes||yes||yes||yes||yes||no|
|BeFree||57g||Hollow Fiber||1.9 L/min||1000L||yes||yes||no||yes||no||no||no|
|Geopress||450g||Ion exchange with Activated carbon||5L/min||350 cycles (250L)||yes||yes||yes||yes||yes||yes||yes|
|Ultralight Water Purifier||309g||Ion exchange with Activated carbon||2L/min||150L||yes||yes||yes||yes||yes||yes||yes|
|Steripen Classic||180g||UV Light||1L/ 90sec||8000L||yes||yes||yes||Pre-Filter to reduce particulate||no||no||yes|
|Pristine Water Drops||98g||Chlorine Dioxide||1L/20mins||10 drops per 1L (120L)||yes (extended wait times)||yes||yes||no||no||no||yes|
|Aquatabs||28g||Sodium Dichlorolsocyanurata||1L/ 40mins||1-2 tablets per 1 L of water (up to 50L)||yes||yes||yes||no||no||no||yes|
The role of activated carbon.
Activated carbon has long been used in treatment devices because of its adsorptive properties—it attracts many types of molecules to its surface and traps them. Carbon is also highly porous, so a small piece provides lots of surface area.
For these reasons, activated carbon is great for catching many contaminants that are so small that they pass through a microfilter. These include tastes, odors, pesticides, herbicides and pharmaceutical byproducts. Carbon can also pull out some heavy metals.
However, it’s important to know that activated carbon has its vulnerabilities. Carbon is best used as a secondary removal media—another level of protection after you’ve filtered out (or purified water of) the microbes. This is because:
1.) When the water’s contamination level is high, the surface area fills up quickly;
2.) If the water’s flow rate is too fast, carbon is less likely to catch all the contaminants;
3.) Adsorptive filters, like carbon, don’t indicate when their surface is full—you have no way of knowing when it’s no longer doing its job.
Activated carbon can make water more enjoyable to drink and adds an extra level of safety, but it’s still important to research where you’re going, and the types of filters and purifiers ideal for those environments.
Minimize your risk:
The Colder the water the better; Avoid pulling water from muddy bottoms of lakes and streams