I think liver fluke is a problem in still water, so if you use water from fast flowing streams and rivers, you should be fine.

I'm overly cautious. I treat and boil.

I am more inclined to worry about ticks, sneaky little critters...

Oooh - at last, my specialist subject!

I did liver flukes for my O level biology - and the good old british ones don't burrow through your skin or anything nasty like that (well, not as far as I'm aware anyway - unless you happen to be a snail).

Back in the sixties when I studied the common liver fluke, it was estimated that about half of UK grazing livestock was infected to some extent. I doubt that has changed. This sounds alarming, but it isn’t really – unless you are in the habit of eating grass (or delicacies like wild water cress).

The liver fluke requires two animals to reproduce – a mammal and a freshwater snail.

Adult liver flukes ensconced in their host produce eggs which pass from the liver to the gut and thence to the outside world via the host’s faeces. Eggs later hatch releasing a larva which, if the faeces are deposited in water or boggy ground, can swim freely. It specifically targets the freshwater snail (the sort you see in your garden pond). Inside the snail the parasite develops into multiple larvae that later emerge to encyst on vegetation.

The life cycle is completed when the grass or whatever is eaten. The encysted larvae come to life in the gut, migrate through the gut wall and travel to the liver where the adult fluke develops and it starts all over again.

So, I reckon free flowing upland water will be just fine, Tony. Drinking fresh cold water from the stream is one of life's great pleasures.

The Challenge offers many things to damage your liver, and the fluke ain't one of them!

p.s. I am always careful about lowland/pasture/grazed areas - e coli etc being my main concern (I carry purifying tabs just in case there is no option). I never take slow or still water.

Phil, I am in total awe!

You kept that quiet - I really had no idea that you had an 'O' Level!

You'll be doing all the navigation from now on.

I almost got one in woodwork too!

I could have put all that, I got my O' Level Biology too, but went for the short version :-)

Hey Phil, in that case bring your tools and you can build new bridges across burns for us all as we go! (Payment in liver-damaging liquid, of course)

I have never filtered water West of Tarfside on the TGOC. But avoid any water where there is evidence of livestock or it is not fast moving.
I currently use either a Sawyer http://www.superdelios.co.uk The Delios has a finer filter but the Sawyer is easier to use.
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" target="_blank"> or http://www.superdelios.co.uk The Delios has a finer filter but the Sawyer is easier to use.

With the Sawyer and Delios you squeeze water from the bottle you filled up in the stream. Be warned you can still get cross contamination. Wipe down with a rag the whole thing before filtering to prevent contaminated water dripping into your clean water. I used a Sawyer in the USA and still got ill. Also never blow the back end with your mouth to flush out excess water. As that is contaminated water potently. Use the squeeze bag to blow air through the filter to clear it out.


The Delios cleans peat stained water better I found. But has a slow flow rate. The Sawyer is way better all round and not expensive.

I have never filtered water West of Tarfside on the TGOC. But avoid any water where there is evidence of livestock or it is not fast moving.
I currently use either a Sawyer or Delios if I think water may need filtering. Especially in the East, or Peaks.
The Delios has a finer filter but the Sawyer is easier to use.

According to the info on the web sites, the Delios has a 0.2 micron filter and the Sawyer (mini and squeeze) a 0.1 micron filter. Both are good, but as Andy says, the Sawyer is easier to use and has a faster flow rate. It also lasts longer and can be back washed with a supplied syringe. Recommended.