Think about where you will be hiking. I did a lot of trips in urban areas. To find water was never a problem. For Europeans venturing into the US the taste of US tap water is a problem. Even when ordering a coke in a restaurant: You will taste the chlorine in the water.
When hiking 14 or more hours a day in the heat your body will lose a lot of electrolytes and minerals. You can drink the best water in the world but you will get sick because of not replacing electrolytes. It is the same feeling like you may encounter after partying hard and drinking a lot of alcohol. Mr Coyle, trail name Seven and known for his hiker trash videos once described it as the feeling of lyme disease. Your water can be fine; you feel sick anyways. Therefore: You need to slow down or to replace the washed-out minerals. This can be achieved by drinking Gatorade or other fancy and sometimes pricy sport-drinks. Hardcore hikers like Anish relay on drinks from a company called Nuun from Oregon.
In many parts of the world water treatment is a must. There are cows. There are bacteria. You risk to get giardiasis. On the AT there is an additional risks: Noro virus. However, against viruses most filtration methods are useless. When in overcrowded shelters there is only one method to be sure to not get the Noro-Virus: Don’t move into the shelter and avoid the contact to other human beings. Use hand-sanitizer everywhere.
There are several methods to tread your water. Forget about cocking it. Most fast hikers don’t carry a stove at all. Many more civilized hikers send their stove home on the AT – it is a lot of effort to cock and in the specific application of thru-hiking meals don’t give you enough calories. Nobody is cocking four meals in a row.
There is chemical treatment. However, many of us feel uncomfortable with the idea of drinking several liters of chemical treated water for weeks.
There is the steri-pen. However, this is an optical method. As the water is purified with UV-light, it will work only in clear water. If the water is murky, the method is unsafe because the UV light will not penetrate the dirt enough. It is in the desert on the PCT and the CDT where you sometimes must drink the same water as the cows. The farmers don’t educate their cattle about bathrooms, so cows will do their business right into the water you are forced to drink. This water will be murky. You can read in this blog how it feels to hike with giardiasis. It’s not funny.
Then there are filters. And there is exactly one filter suitable for thru-hiking: The sawyer standard size squeeze. If you hike in the winter, you must keep your filter from freezing. Once frozen it will no longer work because water expands when freezing. Therefore, it rips the filter-membrane apart. The sawyer mini has a horrible flow rate. I tested it. There is nothing more frustrating than beeing fast but loosing time at a remote source because your filter is slow.
You will need to back flow the filter to keep its flow rate on an acceptable level. They give you a syringe when you purchase it. However, nobody packs out a syringe. The caps of sporty water or Gatorade bottles will fit as well. Test this at home or ask other hikers.
Forget about the products of the Katadyn company. They claim to be the number one filter in terms of sales in the US. It may be true. However, we all know how most individuals on this planet move in and out of the beautiful outdoors – with a car. Katadyn filters are simply too heavy for thru-hiking. They introduced a new product recently, the befree filter. It doesn’t fit to a standard plastic bottle. Sawyer does. I’m sorry to not be able to write something better about them, of course it hurts my patriotic feelings.
To further enhance your filtering experience, you can build your own carbon filter. If you want the combination of a Sawyer and carbon you are forced to do so. There is another filter that will give you carbon from the factory: The Renovo trio. Unfortunately, the flow rate is again an issue. An indeep review can be found here. Carbon filters remove bad tastes from water.
Once you have filtered your water you may want to carry it. Forget about the plastic bottles you can get in outdoor stores: They are too heavy. Simply use a generic plastic water bottle and store it on the outside of your pack. You don’t want to open your pack every time you need to replenish your water.
There is also a practical reason for going with cheap plastic bottles: They can be replaced every other week at nearly no cost. For hygiene reasons this will be a good idea.