Few things are as refreshing as drinking all-natural water straight from a cold mountain stream, untainted by chemical treatments. Or to just plunge your face into a spring on a hot day and quench your thirst without fussing around with filters, pumps, and hoses.
If you are smart about choosing your water source, you could go for days, weeks, or even years without treating your water and never get sick. It's a gamble, but after spending a few days stepping over moose poop, or seeing a bloated dead animal floating in a water source, or worse yet, having to witness your friend doubled over with stomach pains and running off into the trees to decorate the forest in vomit or explosive diarrhea... Anyway, what I'm trying to say is, that stuff kind of diminishes the "all-natural" romanticism of drinking from a cold mountain stream, so I treat my water.
Everyone has their own preferred method, but here’s what I do.
My Water Treatment Method
My method for treating drinking water in the backcountry is a combination of household bleach (one drop per 16 oz.) and/or an inline or straw filter. And don't forget the often skipped step of cleaning your hands after touching potentially contaminated water. I carry a small bottle of hand sanitizer for this. Not doing so could negate everything you do to treat your water.
Ingesting enough undiluted bleach is most definitely toxic, but according to the Centers for Disease Control, even in cases where household bleach was accidentally ingested undiluted, there have only been minor cases of negative health effects reported. Due to the horrible taste of undiluted bleach, it's unlikely that someone could accidentally ingest a dangerous amount. And since I only carry one ounce into the woods, which I heavily dilute over the course of a couple weeks, there's little I could do to harm myself with it. Bleach is also safe for the environment. If you accidentally spill some, it will dissipate in a few hours. It is also safe to dump unused bleach down a drain which leads to a municipal water treatment facility.
Why I use bleach
Since I only carry one ounce into the woods, which I heavily dilute over the course of a couple weeks, there's little I could do to harm myself with household bleach. Ingesting large amounts undiluted bleach is definitely toxic, but according to the Centers for Disease Control, even in cases where undiluted household bleach was accidentally ingested, there have only been minor cases of negative health effects reported. Due to the horrible taste of straight undiluted bleach, it's unlikely that someone could accidentally ingest a dangerous amount.
The amount of bleach being carried is also safe for the environment. If you accidentally spill some, it will dissipate in a few hours. It is also safe to dump unused bleach down a drain which leads to a municipal water treatment facility. Although, it will kill bacterial in a septic tank, so only dump it down a drain if you know where it's going.
While chemical treatments will kill most things in the water, none kill everything. And none work as well on protozoa, like Giardia and Cryptosporidium, as boiling and filtering. Bleach, however, is just as effective at killing protozoa, bacteria, and viruses as iodine, and nearly as effective as Chlorine Dioxide treatments, such as AquaMira.
I can also add 4-5 drops of bleach to 8 ounces of water in a cook pot to sterilize my toothbrush, eating utensil, trekking pole handles, and cook pot. And every thru-hiker, who lives for weeks without running water, knows how important it becomes to keep your toothbrush clean.
Other chemical treatments will run about $10-15 to treat up to 30 gallons of water. A gallon of bleach runs about two bucks. The most I ever paid for bleach was in a small gas station near the Long Trail in Vermont, $3 for a half gallon.
If stored at room temperature, bleach will last for 3-5 months from the day it's delivered to a store and a gallon will treat over 3,000 gallons of water. If the bottle is kept closed when not in use, the biggest factor that will shorten shelf-life is the storage temperature. That is because sodium hypochlorite, the active chemical in household bleach, breaks down quicker in higher temperatures. According to Clorox, the amount of sodium hypochlorite they add to their bleach depends on the season. They add more in the summer to compensate for the higher temperatures. Check your label. 6% hypochlorite is the norm, and the amount my recommendations below are based on. A higher concentration will last longer before it has broken down to ineffective levels.
I've never had a problem finding bleach in a resupply town, regardless of size and remoteness. Most gas stations on the outskirts of town also carry it. I have had trouble finding other chemical treatments, however. That's why I tried bleach for the first time. I was in a decent sized town, but nobody sold iodine or chlorine dioxide-based treatments.
I will also restate that if you're resupplying during a long distance hike, it is safe to dump what you don't use down a sink or toilet. Actually, it will clean pipes and keep them clear. It's also safe on a city's sewage system. If it's going to a septic tank, however, it could kill the bacteria needed for a septic tank to work properly.
A one ounce eyedropper bottle full of bleach weighs about 1 ounce and lasts about two or three weeks on the trail.
How I use bleach
My method is based on recommendations by the Centers for Disease Control, the American Red Cross, and hours of additional reading. If you find any mistakes or have questions or suggestions, please contact me at firstname.lastname@example.org. I will always be happy to learn something new and will update this information accordingly.
1. Fill an eyedropper with bleach.
Before heading out, I fill an eyedropper bottle with common household bleach. I use an old Visine bottle or breath drops bottle. Since bleach will degrade in direct UV light and become less effective, don't let it sit in the sun.
To fill the bottle without spilling bleach, when a funnel isn't available, use a ZipLoc bag as a funnel. Put the desired amount of bleach in the bag. Hold it by one of the top corners and cut a tiny bit off the corner that's above the bleach. Tip the bag and pour the thin stream of bleach into the dropper bottle.
I keep the bottle in a ZipLoc freezer bag to prevent damage to gear and clothes. So far, I have not had a problem.
2. Fill your water bottle with water.
The best water source is actually the top few inches of lake water. The longer time under the sun’s UV rays does a lot of the sterilization for you. Otherwise, a spring or swift moving creek will be fine.
No matter what chemical treatment you use, if the water source is not clear, tie a bandanna or some other cloth around the top of the bottle when filling. If your water is still cloudy, let it sit until all sediment has settled, then pour the clear water into another bottle before treating. Chemical treatments are much less effective if the water is not clear or contains free-floating organic material. Organisms that are clinging to free-floating particles are harder to kill.
3. Add one drop of bleach per 16 oz. of clear water.
Use two drops if the water is really cold, cloudy, or discolored. If your bleach is not the common 4-6% solution of sodium hydrochlorite you may have to use more or less. The amount of sodium hypochlorite added to bleach may depend on the season. For example, more may be added in the summer to compensate for the higher temperatures. It could be as high as 10%, so check your bleach bottle’s label and adjust dosage accordingly.
4. Shake it like a Polaroid.
5. Screw the cap nearly all the way on, then squeeze the bottle until it starts to pour out, and then tighten the lid.
This ensures that the entire bottle, including the cap and threads, get disinfected.
6. Wait 30 minutes. And in the meantime, clean your hands with a hand sanitizer. Not cleaning your hands after touching a contaminated water source could negate everything you have done to prevent a water-borne illness.
If after 30 minutes, your water does not have a slight chlorine smell similar to municipal tap water, repeat steps 3 through 5. Think of bleach as an army of soldiers you're sending into battle. They kill organisms, but die in the process. The more organisms there are to kill, the more soldiers you need. That's why it may be necessary to treat a second time. And why sometimes you'll smell or taste more chlorine than other times. Keep in mind though, this isn't the fault of bleach alone. It's true for any chemical treatment.
One last thing, the decomposition rate of bleach increases by a factor of 3.5 for every 18° F increase in temperature, so if not stored at 60-80 degrees, it's probably a good idea to dump it out and replace it after a couple weeks to be safe.