Safe to drink water filtered in caves?

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Re: Safe to drink water filtered in caves?

Postby Squirrel Girl » Dec 27, 2018 1:04 pm

LindaPeterson wrote:Hi all,
I've searched the forums here and haven't found an answer to this yet.
Is it safe to drink cave water if you're judicious about where you draw it and you filter it with a hiking water filter?
I ask b/c I hear that the cave water can have a lot of contaminants like ag runoff, biological bad stuff, effluent from sceptic-tank fingers, and some chemicals I wouldn't have thought of -- like Mg and Fe oxides. (kidney stones?)
So, I've been filtering my water in the cave instead of brining in gallons... and I'm wondering.
I use an MSR ceramic filter that I take hiking with me. It sure is nice to carry a 6 oz filter and an single water bottle and just filter more water when I find water sources (I'm in southern IN, lots of water).
Will the ceramic filter be fine? (It is rated as a "purifier") Should I be looking at a carbon filter instead to bind those ions?


I think you're on the right track. Stream water in a cave would be seriously suspect. Every bit as bad as drinking from a surface stream. The water that drips/runs from speleothems, would presumably be more pure as it gets filtered by flowing through tight rock spaces. Still, I wouldn't drink it straight! I'd use a purifier for bacteria and so on. Drip water ought to be be less toxic from the chemicals, but I don't know. In Indiana, you probably have a lot of those and cow poop! I doubt Mg or Fe oxides would make any difference to you. The Ca would be high and if you have trouble with kidney stones, it might be an issue. But if you don't have a problem with them, just drinking higher Ca water won't cause them out of the blue. I have WAY more Ca in my water here in NM than I had in VA. So it's "normal" sometimes to have high Ca.

My take away is that so long as you filter for bacteria and the link, you're good to go. I mean, overall, how much cave water do you drink as a part of your overall life?

I'd be interested to hear any more information if anyone has real data.
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Re: Safe to drink water filtered in caves?

Postby captnemo » Dec 27, 2018 3:06 pm

Unless there are no people/livestock etc anywhere near the cave and its water source, (So I'm thinking that big hole in Canada is probably the only one left) I'd say treat it as contaminated. Remember there are a lot of filters out there that don't meet the <1.0 micron size to prevent crypto getting through and I don't believe any of them prevent viruses so boiling or a combo filter/disinfectant is your best bet.
Once more I turn to a reputable source- the CDC https://www.cdc.gov/healthywater/drinking/travel/index.html for your answer. They have some good info especially about how some dishonest filter manufacturers try to convince people they are more effective then they are and what to look out for.
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Re: Safe to drink water filtered in caves?

Postby ohiocaver » Dec 27, 2018 11:33 pm

If you filter it or use a filtration straw you should be fine. I've drunk water pumped from muddy cattle wallows in Peru (after filtering and microfiltering) and had no ill effect. Many people drink water direct from springs. It's not uncommon to see them filling 5-gallon jugs from a spring.
If your question is about a survival situation (I don't know anyone who carries a filter on a day trip), drink the water. Any bugs won't show up for a few days when, you'd hope, you'll be back above ground and have access to medical help. Dehydration causes tiredness and bad decisions. Drink up!
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Re: Safe to drink water filtered in caves?

Postby trogman » Jan 3, 2019 8:24 am

I regularly use a filter so that I don't have to carry as much water on caving and ridgewalking trips. As far as I know I have never had any serious issues from doing so.

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Re: Safe to drink water filtered in caves?

Postby bennettbike » Apr 15, 2019 6:52 pm

A filter is a good idea, I once drank water from ellisons and then when I got near the pit entrance I found a dead turtle in the water. Bless that turtle... I have pet turtles, aside from it being sad I got worried.
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Re: Safe to drink water filtered in caves?

Postby trogman » Apr 16, 2019 7:57 am

Just wanted to add a caveat to my earlier post. While I do regularly use a filter, I did have a cause for concern recently. One day during a survey trip, I used a filter almost exclusively for my drinking water for the day. The next day I noticed I had diarrhea for about half the day, and I wondered if it had anything to do with the water. A few weeks later I received a Christmas gift of a new filter, and upon reading the instructions, I noted there were prominent warnings about keeping the filter from freezing. This was something I had never thought about, and I realized that mine had probably been frozen more than once through the years. In fact, my favorite time to ridgewalk is when it is super cold. When the filtering medium in a water filter gets wet, it pretty much retains some moisture indefinitely, and is nearly impossible to dry out. When they get frozen, it damages the filter and allows contaminants to get through the pores, making the filter essentially of little or no effect. Also, it is impossible to know if this has happened and to tell if your filter has been compromised. So if you are in doubt, it is best to throw away your filter and get a new one, which is what I did. Now I am diligent to store my filter in the house and not in the shed, and when I walk with it in cold weather, I keep it close to my body so it will not freeze.

I imagine some or most of you already knew this. However, if you were like me (clueless), then hopefully you just learned something. :grin:

There are other water purification methods out there such as Steripen and chemical methods. However, the simple filtering method remains the most efficient and cost-effective one out there, at least as far as I know. If anyone has had any experiences with these other methods I'd be interested to hear about them.

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Re: Safe to drink water filtered in caves?

Postby bennettbike » Apr 17, 2019 5:53 am

Definitely did not know that, thanks ^
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Re: Safe to drink water filtered in caves?

Postby bobby49 » Apr 17, 2019 11:09 am

First of all, there are all sorts of filter elements. Some are ceramic, and they are most greatly affected by freezing. On one trip, there was a $1,000 ceramic filter in use. It got frozen, and then it shattered into pieces. Sometimes you can purge all of the water out of a ceramic filter to prevent that, but most typically you cannot get all of the water out. The filters most commonly in use have a synthetic filter. These are affected by freezing also, but not quite as badly.

You can boil the water, but that requires a stove, fuel, and a pot. You can chemically treat the water, but that generally requires a long "contact time" in order to do a good job. That is suspect if you don't really know what kind of pollutants are in the water. Chemicals like iodine work pretty good at killing bacteria and viruses, but some people are adversely affected by the ingested iodine. Chlorine can also be used, but it is not as powerful as iodine.

In some third-world countries, the water is severely polluted. Then if you figure out what the likely pollutants are, like bacteria and viruses, you can use two of the above methods.

Outside of caving, I use a gravity filter for summer backpacking. The actual filter element is small, so I can detach it from the rest of the filter system and store it in my pocket.
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