Some dilemmas concerning use of UV water treatment vs water filter

Question

The trekking season is starting, need some help with few dillemas with more experienced hikers and outdoor enthusiasts.

Last year I got seriously ill for 2-7 days after drinking water from mountain source, which was supposed to be clean. This year I need some filtration or UV treatment, but I don't know how are your practical experiences to help me decide.

Scenario 1: Drinking water from mountain huts in central Europe. They use rain water or cisterns I don't know precisely. Should I use UV lamp of water filter on that water? Preferred method. Would that made it good enough to safely drink it or not?

The thing is they transport water with helicopters to some huts and it is almost as expensive as meal+overnight stay combined if you do hard hikes and drink a lot. And there is environmental issue from plastic bottles. I would like to avoid too much plastic bottles.

Scenario 2: Different flowing rivers in wilderness. There won't be any noticeable pollution or human presence above the water collection. Is UV or water filter enough? I guess probably is.

Scenario 3: Water near pastures in alpine terrain with mountains. The water is usually flowing, but perhaps there is reservoir, pond near cattle and could be not save to drink. Is UV or water filter enough?

Scenario 4: Emergency situation. Need to drink it from a pond, lake. The water is standing, perhaps a little muddy, but without any noticeable human presence.

I don't know there is potential issue with safety of UV lamps. Filters filter out most protozoa and bacterias. UV lamp just destroys part of their DNA and you still ingest that damaged DNA from deactivated protozoa and bacteria.

I don't know, what would you do and what are your experiences in that or similar scenarios.

Answer 1

I'm a big fan of UV lamps.

Pros" Smaller & lighter than filters. Filters can also get clogged. I've had that happen with micro algae. I can usually purify my water faster that my friends using filters. Once I fill my bottle, I can step away from the water source while purifying and allow someone else to the water.

Cons: UV lamps require clear water. You can use a pre-filter (a very tight mesh screen, prob about the equivalent of a coffee filter) to remove any but the tiniest floaties in the water before you purify it. You have to be able to fill your water bottle up before you use the UV. I've have issues where the water source was shallow & did not allow me to dip my bottle in. Bring a small cup so you can transfer water into your bottle.

Either way, bring some chemical tabs for backup in case your UV or filter fails.

Answer 2

You would have to be awfully remote from both people an animals to be sure natural water contains no pathogens. Treat everything.

As for the "threat" of drinking pathogens that have been killed--the same thing applies to water that has been chemically treated. Note that that includes ordinary tap water (assuming you're in a place where the tap water is safe to drink.) Thus you've been doing it all your life, it's not going to suddenly hurt you when you're out in the wilderness.

As for the water that is "undrinkable"--normally this simply means it's as it was found in nature, not treated so as to make it safe. Remember that most filters do not get all the viruses and chemical treatment takes 4 hours against some pathogens.

Answer 3

According to Department of Health, Western Australia

UV light is normally effective against all viruses, bacteria and protozoa. However, some microorganisms such as Cryptosporidium and Giardia have protective or thick cell walls that some low power UV light systems are not able to penetrate. (It is important to make sure the UV light disinfection systems are specifically designed to kill these microorganisms if necessary.)

Answer 4

I use a combination of UV light, Tablets, and boiling my drinking water. I've been hiking and travelling with my UV light & tablets for years and have never gotten sick. The UV light I use (Steripen) is effective against viruses, bacteria, and protozoa including Giardia and Cryptosporidium. However, I double up with tablets and/or boiling when drinking from shallow and stagnant water sources or when travelling in areas with lots of ungulates especially cattle.

Filters are needed for water that is murky, but they are slow, heavier, and tend to clog up. I have a filter that I only bring out in the spring/summer melt season when the water has a lot of sediment and I am drinking from rivers and not lakes.

UV filters are fast, light, but can take some practice to use one correctly and you need to have a wide top bottle.

Chemical treatments are light, easy to use, but can take a few hours before the water is safe and can give the water a distinct taste.

In situations 1 & 2, I would say using a UV light or chemical treatment would be sufficient. In situations 3, I would definitely use my UV light and a chemical treatment and try to boil water if possible. In situation 4 for deep lakes I would use either the UV light, chemical tab, or boil the water. In shallow ponds I would double up and use my UV light and a tablet or boiling.

Remember that in order to be safe water must be at a rolling boil for 1 minute near sea level and 3 minutes at elevation. https://www1.health.gov.au/internet/main/publishing.nsf/Content/cda-pubs-cdi-1998-cdi2209-cdi2209j.htm#:~:text=CDC%20recommends%20making%20water%20microbiologically,for%20one%20(1)%20minute.