Topic
contamination of treated water
Forum Posting
A Membership is required to post in the forums. Login or become a member to post in the member forums!
Home › Forums › Gear Forums › Gear (General) › contamination of treated water
- This topic has 10 replies, 7 voices, and was last updated 1 year, 9 months ago by Marcus.
-
AuthorPosts
-
Jun 29, 2022 at 5:28 pm #3754026
someone asked if it’s okay to have a few drops of untreated water in your treated water container
I might use my treated water container to get untreated water, then want to use it to put treated water into. Can I just shake the water out and call it good? There’ll be a few drops of untreated water left in it which will contaminate the treated water that I put into it. But is it enough to make any difference?
According to the google, 1 drop is 1/20th of a mL. There are are 3785 ml in a gallon. So a gallon contains 75,700 drops of water. So 1 drop is 0.000013 of a gallon. So, the treated water is 99.999% of the gallon.
So, 1 drop in a 1 gallon container is like a filter that’s 99.999% effective.
The Squeeze advertises 99.9999% effective against protozoa. 99.99999% effective against bacteria.
So, putting just 1 drop of water in a gallon is 10 or 100 times worse than the spec’d performance of the filter.
That would say that maybe you shouldn’t have even 1 drop of untreated water, although it may be that the 99.9999% or 99.99999% is way more than needed.
One thing you could do is partly fill your container with treated water, then shake it vigorously and dump it.
When you’re filtering, it’s easy to accidentally drip a few drops of untreated water, but this calculation would say that you should carefully avoid this.
Jun 29, 2022 at 6:29 pm #3754031All of my containers are untreated water, and then I put the filter on when needed to use them.
If I want a clean container, I use an Aquatab, which weighs practically negative weight. Fill container with 750ml of water to get correct ~6 PPM chlorine, and one tablet will nuke it clean in 30 minutes. Then use the water inside to clean the outside of the bottle and other camp stuff that could use a light disinfecting, such as funky underwear and shirts.
Jun 29, 2022 at 6:40 pm #3754032Better not swim and then lick your lips…
Jun 29, 2022 at 7:42 pm #3754037“Dilution is the solution to pollution” is axiomatic in my industry.
Shaking it out and calling it good, yes, will diminish the treatment efficiency, significantly in some cases.
OTOH, putting an ounce of treated water into the formerly dirty container with 1 ml remaining in it, swirling it all around and dumping out 30 ml of treated water would remove 97% of what was in there. Do that twice and you’ve gotten 99.9 percent out of what residue remained in exchange for wasting 2 ounces of clean water.
The more time you do it, the better it gets. Also, the more rinses you perform with a set amount of clean water, the better. 30 ml to get out one ml and repeat with another 30 ml gives 1 – (0.03×0.03) = 99.9 but 15 ml used four times is 1 – (1/16)^4 = 0.99998
Jun 29, 2022 at 8:04 pm #3754040“30 ml gives 1 – (0.03×0.03) = 99.9 but 15 ml used four times is 1 – (1/16)^4 = 0.99998″
sheesh, all that goes without saying.
I’ll treat my large soft camp bottle and leave it out in the sun. The sun fries any left over little buggers good. Buggers divided by sunlight plus iodine*** equals safe water.
that’s my mathematical take.***I think REI still sells iodine tablets.
and yes to ‘dilution is the answer to pollution”. I’m guessing our bodies can fight off a miniscule amount of bad bacteria that our filters may have missed.
Jun 30, 2022 at 7:17 am #3754065“I’m guessing our bodies can fight off a miniscule amount of bad bacteria that our filters may have missed.”
Yeah – maybe 99.9999% or 99.99999% is unnecessary – you probably don’t need that much filtering
Jun 30, 2022 at 7:22 am #3754066“Dilution is the solution to pollution”
That’s funny, I was hiking with Doug and he mentioned that and attributed it to David :)
Sometimes, dilution causes a problem, like it would be easier to extract CO2 from a smokestack with high CO2 concentration, than free air with low CO2 concentration
Not that I advocate CO2 extraction – probably not practical, just an excuse to continue burning fossil fuels
Jun 30, 2022 at 7:29 am #3754068I rarely put untreated water into my pint bottle that I use for drinking
I think I’ll just do what David suggested – rinse it out a couple times
Jun 30, 2022 at 10:46 am #3754080There is also the ‘human factor’… If you adopt the thought that ‘a little does not matter’, then at some point ‘a little’ can become more… and more…
Best to keep good habits… similar to using your turn signal automatically whether there is another car in the intersection or not. I just never use the dirty water bottle for treated water… always keep them separate. Though your mileage may vary…
Jun 30, 2022 at 10:59 am #3754084Or a belt & suspenders approach: Toss a bit of chlorine or iodine in the dirty water bottle before or after use so what remains in there is being treated, chemically.
Jun 30, 2022 at 5:29 pm #3754111This video (and the whole 5 part series) from Gear Skeptic lays out excellent examples of why that extra .00001% COULD make a difference, particularly if you are on the trail for a hundred days on a Thru or are drinking very dirty water.
I think he shows that something like 3% of hikers will theoretically get ill on a 150 day PCT hike drinking treated water 100% of the time because of the buggers that slip through .0001% of the time. Some cysts (Giardia if I remember right?) only need 1 or 2 to make you sick.
I dont fret about it, but i do rinse with fresh water a couple-few times per david’s dilution method if a little dirty water contaminates my bottle. Personally I always have time to prevent waterborne illness in the backcountry. Havent been burned…yet.
-
AuthorPosts
- You must be logged in to reply to this topic.
Forum Posting
A Membership is required to post in the forums. Login or become a member to post in the member forums!
Our Community Posts are Moderated
Backpacking Light community posts are moderated and here to foster helpful and positive discussions about lightweight backpacking. Please be mindful of our values and boundaries and review our Community Guidelines prior to posting.
Get the Newsletter
Gear Research & Discovery Tools
- Browse our curated Gear Shop
- See the latest Gear Deals and Sales
- Our Recommendations
- Search for Gear on Sale with the Gear Finder
- Used Gear Swap
- Member Gear Reviews and BPL Gear Review Articles
- Browse by Gear Type or Brand.