Drinking burn water is ok as long as you don't have it lying around festering in your bottle/ container for too long. I once filled up from the Sligachan burn on Skye, but then left the half-used water in the bottle in the Caberfeidh-Mobile whilst I visited a young lady friend for a few days. The car sat baking in the sun of a rare highland heatwave, my water bottle incubating some horrific life-forms unknown to science. After a few days I got back in the car, drove off and drank from the bottle. I had swallowed the fetid water before I realised just how rank it was. Later I had to stop at the Clachaig to use their facilities. Later still I threw up all over Glen Coe. I vomited my way across Rannoch Moor, Bridge of Orchy, Crianlarich, Callander, Doune, Perth, Dundee, and all the way up to Aberdeen. Then the diarrhoea set in. For a week or more I suffered vomiting and diarrhoea, muscle cramps, joint aches, blinding headaches and generally wishing I was dead. As I recovered I was left with a horrific dose of flatulence the like of which Hell hath no, which was unfortunate as I was then posted to a drilling rig in the North Sea. The rig was a jack-up, a mobile drilling rig which was towed into the Danish Sektor, a sektor notorious for the Hydrogen Sulphide gas. The gas detectors were cranked up to eleven... You can see where this is going, can't you? I am possibly the only person in history to shut down production on a rig by farting. Every time I 'vented gas' as we say in the industry, the alarms would go off and we had to muster at the lifeboat muster stations. All through the night, over and over... Luckily no-one twigged it was me, I would have been lynched!
- Danger - gas!