I know people that filter/treat in Scotland and people that swear it's perfectly fine not to. I would be the one in a million that caught out, so I treat. It's personal choice like everything else, if you're happy don't, if you're a girly wuss like me, do!

I've never treated water in a lifetime of trundling around Scotland, Ireland, The Pyrennees and other places that I seem to have forgotten. But a lot of this has to do with your own, ah, stomach flora . . . I guess mine are in a relatively robust condition.

Having said this, I would never drink from a lowland river, draw the line at lakes, and look for fast-flowing oxygenated sources.

Nevertheless, I'm about to break with this habit. Next Thursday I'm setting off for a couple of weeks along the Franco/Spanish border in the Basque country. And I know that for the first week I'll be in country with abundant cattle, sheep and horses. I'll be taking Lifesytems Chlorine Dioxide Droplets. For £7.50 these will treat up to 60 litres of water, and apparently kill bacteria, viruses and cysts.

In my younger daze I lived on a sheep farm in Co Wicklow. We took our water from a tank on the roof. But we would never take water from the stream, owing to the risk of the deeply unpleasant liver-flukes than can be transmitted from sheep to humans.

At the risk of taking this thread into darker territory, I'd suggest that good personal hygiene on an extended back-packing trip is of great importance to avoid cross-contamination. Now wash your hands!

I have used a Katadyn filter in the past but I am leaving it at home.
Trying to lighten my kit.
The delios filter sounds ok but who stocks it?
I never used to bother about purity of water but in some of the more agricultural areas it can be problematic.

Unfortunately the Delios filter is no longer available in the UK. As a Japanese firm, it was affected by the tsunami and the UK distributor is no longer answering emails, presumably returned to Japan. It's the best filter I've used. Hopefully, they will return at some stage.

I can echo what Humphrey says about personal hygene.

On the two organised trekking holidays I've been on most of the participants got Peruvian foxtrot or Kathmandhu belly.

I was paranoid about personal hygene. The food was good and did not cause me any problems.

Nor did the folk who cross contaminated each other's food and drink!!

I only drank boiled water.

Leave it.
I have never used one.
If you want something, take. Delios.
55g and fits on a platypus.
No good if you cannot get one.
In that case treatment tablets.

In the making of the film 'The African Queen', filmed in tropical Africa, everyone apparently got serious tummy problems, except for Humphrey Bogart.

His secret? He never drank water...

Frederic, I'd take you up on that, only I'm starting at Dornie! If nobody alse wants yours, I'll check the geography and timing tomorrow and see if it's possible......55g, you say?

I have always treated water. I'm sure I have treated LOADS of water that would have been perfectly OK to drink without, but I reckon this have to be the lesser of two evils as compared with drinking without treatment water that needs it.

Yet more allergies come into play here, though. I have to steer clear of the chlorine tablets ... so I always used the Iodine ones. But they've banned them now and you can't get them any more!

So my new toy for this Challenge is a UV sterilisation system called a SteriPen. Complete with batteries, it tips the scales at 195 grammes.

I think I can live with that

195g

That is very nearly a packet of



I couldn't live without that.

Good on you and good luck, Frederic.

Drink tea, you have to boil the water which kills most bacteria. In over 40 years of camping in the UK we have never felt the need to use a filter for ourselves. The one time we tried filtering water for our son to drink the filter blocked with fine peat particles after filtering just a few liters!
The code for this post is M GUT!

It does depend to some extent on how used to wild water your digestive system is, I think. If you've only ever drunk tapwater or filtered water, I would have thought it would be best to filter or boil or otherwise chuck tablets in. Streams in spate after heavy rain carry a lot more bugs than they would otherwise do and I would always boil water or use sterilising tabs for those times, but otherwise I'm happy to drink most peaty gunge, whether or not the fabled dead sheep in languishing upstream.