Using Alum to Clarify Muddy Water on Trips

Good information, thanks

After the floc settles is there remaining alum dissolved in the clear water?

Is this unhealthful?

Thanks for this article Rob. This subject is near and dear to my heart. I live and explore on the Colorado Plateau and often run into nasty water of the kind you’ve pictured. My alum experiments so far have been a bit hit and miss, so I’m hoping you can answer a few questions. 1) Is the alum that one would find in the spice rack at the grocery store acceptable to use for water treatment? 2) How important is using calcium hydroxide? Does it affect flocculation? 3) Do these chemicals have expiration dates? Thanks for any tips.

I have also used Alum on the Colorado Plateau and love it.  Never found a need for any CaOH2.  I do stir, then let it sit for 2-3 minutes and stir again. The second stir seems to quicken the process.  Here is a picture of a cheap settling container from a gallon milk jug with a little pour notch for making decanting easier.  A little string to tie it to the back of my pack and it is almost weightless.

Whitewater rafters running Arizona’s Grand Canyon on the Colorado River often must treat muddy river water for drinking and cooking. The two methods I’ve used are alum (without lime) and overnight settling, followed by disinfection with plain chlorinated bleach. Both worked well, but some fellow travelers didn’t like putting more chemicals into their drinking water, so we mostly used settling.

We used several five gallon (20 liter) plastic buckets for water treatment, since they have multiple uses on raft trips. Worked well for up to 20 people.

Slowly pouring off clear water without disturbing the settled sediments was a valued skill. Helps if you stop early, not trying to capture the last few quarts (liters).

Haven’t had to use either technique on backpacking trips – yet. Thanks for the reminder.

— Rex

Good tip about the milk jug Arthur. Thanks.

Would this method also work for clearing glacial flour from mountain rivers?

There’s a version of this type of product sold in the US (haven’t looked anywhere else) named Chlor Floc.  It adds chlorine-based disinfection. Individually packaged in convenient 1-liter doses.  It’s expensive, but we don’t use it a lot – mostly if the Colorado running muddy. Always carry some packets just in case.

https://www.rothco.com/product/chlor-floc-military-water-purification-powder-packets

If you look around, it can be found much cheaper than from Rothco.

We use 1-gallon freezer ziplock bags, mix it up, decant through a bandana or similar.

The initial Editor’s Note should probably be tweaked — looks like the triple negative was one too many. =)

The packets of alum plus have been available for as little as $.15 in the past.

Settling, followed by filtering with two layers of cotton cloth and SODIS pop bottle sunlight disinfection is commonly used in third world countries. Alum speeds up process.

Diane, Yes, it should help settle glacial flour.

“five gallon plastic buckets . . .  have multiple uses on raft trips.”

I loved the write-up on sump pumps in the WestMarine catalog because after explaining gpm, discharge head, watts and amps, they note that “Nothing moves water as fast as a motivated sailor and a 5-gallon bucket.”  These were one of my stocking stuffers around the office this year: 

and make it much more comfortable to haul around a full 5-gallon bucket.

Even though self-bailing boats have pretty much made highly-motivated bailing obsolete, you’ll still find plenty of 5-gallon buckets on whitewater rafts, especially for overnight or longer trips.

Besides water purification:
– Three- or four-bucket dishwashing systems (rinse-soap-clorox-rinse)
– Urine buckets when river access is sketchy (“and you can pee right into the stream”)
– Handwashing after using the groover, with foot pumps on luxury trips
– Rinsing veggies for dinner
– Seats in camp for those that didn’t bring something fancy. Pro tip: upside down.
– Shopping for groceries from coolers and rocket boxes
– Splashing boats down on sunny days. What is the sound of two tubes exploding? BTDT.
– Cooling off in hot weather, which often leads to …
– Raft-to-raft water fights
– Collecting hoopy, cam straps, carabiners, and miscellaneous gear after trips

And more uses I’ve probably forgotten. Never push off without them.

Didn’t have no fancy plastic handles when I started. Usually pulled the wire handles off, bored a hole into the top edge with a big pointy knife, and threaded a loop of hoopy through to clip onto the boat somewhere.

Most of these uses won’t apply to most backpacking trips.

— Rex

PS – Yes, whitewater rafters have strange jargon, too.