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"A 'spate' of walkers tackling the West Highland Way have fallen ill after drinking water from rivers......at least nine walkers passing through Rowardennan on the banks of Loch Lomond have suffered vomiting and diarrhoea in the past month.
Rangers said all nine have drank water from the rivers near Balmaha. All nine also said they filtered the water first but still fell ill.
Three of the hikers told rangers that they had taken water from The Burn of Mar near to Conic Hill.
The National Trust for Scotland Ben Lomond Ranger Service has warned walkers not to drink water from the river due to livestock upstream."
https://www.heraldscotland.com/news/25148727.warning-west-highland-way-walkers-several-fall-ill/
I don't use a filter however most of what I drink has been boiled and a coffee bag added. I avoid drinking water downstream from grazing sheep
False sense of security from filters?
Might be a bit more to this. What filter? How well maintained is the filter? etc? Are they all part of one group?
Do they know the illness was even from the water they drank, they could have all eaten something that was contaminated. Or used their filter wrong or cross contaminated it. It wouldn’t take much to use a filter in a bit of a messy way and contaminate your filtered water with unfiltered, leave it in its water holder for a day or so and cultivate a new bacterial colony in it.
Seems to be separate groups over a period of a month. More on reddit. Presumably that 9 is the top of the iceberg Most would not report it.
"I and my group of friends also filled up from this source, as wete many others at tge time if visiting. We were as sick as dogs. unfortunately had to abandon the trek. I assume thousands more are also in the same position.'
Well, yes if lots of independent groups over a month are getting ill, then it sounds very likely that the common source is the water. What's the main illness that bypasses filters then? I would usually suggest a filter as it removes more of the other contaminants that boiling does not, but it seems the NT Rangers are suggesting the opposite. I have a Sawyer Squeeze fwiw. What's everyone else using?
Water filters don't remove, or may fail to remove entirely anyway, certain bacteria and viruses, including noroviruses and rotaviruses.
Adding neutralising tabs or boiling as well may be required.
I have a sawyer somewhere that only gets used when i would probably drink the water anyway for the "oh thats what the smell was" moments ten m upstream.
False sense of security from filters
There's a difference between 'filters' and 'purifiers', filters will take out larger particles and parasitical organisms, but not some of the smaller stuff, like viruses. Purifiers should, on paper anyway, pretty much take out the lot down to chemical contaminants etc depending on the model. It's one of those areas where you want to do some proper research before buying and think hard about the water sources in the area you're going to be in.
Boiling is a pretty good, thorough method of killing anything alive.
On top of that, 'everyone said they used filters' - I'd be asking, did they really? I can imagine some people would fib to avoid looking/feeling stupid. Plus user error, it's quite easy with some types of filter to get the outside bits contaminated and get sick that way. It doesn't take much. Rinse your bowl in contaminated water then use it when it hasn't dried out yet, etc.
Coincidentally or not the water from nearby Loch Katrine was believed into be responsible for a cryptosporidium outbreak in Glasgow in 2001. At the time the water was chlorinated but not filtered
Helpfully, the water authorities who owned the land round the loch allowed sheep to be grazed on it.
Nowadays there is a new treatment plant for the water and no sheep shit in it as they stopped grazing sheep beside the reservoir.
http://news.bbc.co.uk/1/hi/scotland/1622411.stm
Good point about filters missing viruses. It's hard to get it right every time in every situation. Boiling is a faff when you are on the go. Sterilising tabs miss cysts and protozoa. I got sick before with a protozoa infection because I tabbed the water but didn't filter it. Filtering and tabbing might be the best on-the-go option.
Livestock everywhere... then find another water source
The filter I have claims to take out everything to 2 microns so viruses and protozoa
Ive never got sick from Scottish water anyway and thats without a filter
2 microns is pretty crap, definitely wouldn't catch bacteria, let alone viruses.
Presumably it's a msr guardian? 0.02 microns.
Mine states 0.1 microns, and doesn't claim to filter viruses.
Yes, the MSR Guardian is a purifier at 0.02 microns. I imagine there isn't much better than that available that can be packed on a bike or carried.
I'd never much bothered filtering or purifying water taken in the Scottish hills over the course of 50 years, but I was aware that it's a bit of a gamble and that I really should reconsider. I do now have a Water-to-go bottle that tends to come with me on some trips.
From their website...
our unique 3-in-1 filter technology that eliminates up to 99.9999%* of microbiological contaminants, such as bacteria, protozoa and even viruses which most filters cannot deal with. The filter also purifies the water, taking out harnful chemicals and heavy metals. Each filter lasts for 200 Litres.