Before drinking any water, you should treat it to make sure it won’t make you sick.
There are three types of pathogens that could be in the water.
Parasites
The parasites you would likely encounter are categorized as protozoa. These can be in water all over the world including north america. Protozoa are common enough that you should always treat the water just in case because they can make you very sick. The two most common for hikers to come across are Giardia lamblia and Cryptosporidium parvum.
Bacteria
Bacteria can cause severe illness and can be found even in mountain water. Salmonella and E. coli are examples of very serious bacteria.
Viruses
These are not very common in North America, but to be safe, you should treat water with the assumption that there could be viruses in the water.
Treatment methods
Boiling
In order for boiling to work, you have to maintain a rolling boil for at least one minute. This method kills everything and is the safest method in order to ensure the water is completely safe. However, boiling is time consuming (you also have to wait for the water to cool down to drink it) and requires that you bring extra fuel (which is wastes a lot of space and adds a lot of weight.
Filtering
Filters range from very simple to pretty complicated. A filter works by essentially blocking the pathogen from crossing a filter and therefore physically removing the pathogen from the water. Filters must have extremely small pores to protect you from everything. Viruses can be as small as 0.005 micron. So when you shop around for a filter, you need to consider how small it’s pores are to see if what it will protect you from. A very convenient and popular filter is the Life Straw. It allows you to literally drink from a river or lake as if you were using a straw. But beware, that the Life Straw does not protect you from viruses.
Chemical
Chemical treatments work by killing the pathogen. Iodine and Chlorine are two common methods to kill bacteria and viruses, however they don’t work against protozoa. Chlorine Dioxide is supposed to work against protozoa, bacteria and viruses. However, I’ve heard that the EPA does not guarantee this. A good option for Chlorine Dioxide is the Aquamira drops. Make sure you read the instructions on how to properly treat the water with those drops. These can be time consuming like boiling, but at least you can be hiking during that time, you don’t have to be sitting there by the stove.
UV Light
These are electronic devices that use ultra violet light to sterilize the water. They kill protozoa, bacteria and viruses. This is our personal favorite method of treating water because it’s relatively fast. We use the SteriPen. The main downside for these is that you need batteries and might need to bring extras for longer trips or if you are treating water for multiple people. The device could also break down, for this reason, we like to bring some chlorine dioxide as a backup option since they are so small and light. Another consideration with UV light is that the water can be dirty. If there is dirt in the water, the dirt can “provide shade” to the pathogen and therefore allow it to survive the uv light. For this reason, if you are treating mucky or dirty water, you should pre-filter the water. The SteriPen comes with a pre-filter, however if you lose it, forgot it or just didn’t want to carry it, you could use cotton clothing or coffee filters as a pre-filter before using the UV light..
Final thoughts
No matter which method you use to treat water, make sure you know how to do it properly, and it’s a good idea to have a backup plan. Also, you can combine various methods to cover all your bases. For example, you could use a filter to remove protozoa and bacteria, and then use iodine or chlorine to kill any viruses that might have come through the filter.