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Is it safe to drink water from streams in Dartmoor using simple purification methods?

I'm planning a trip and am looking to filter using a Millbank bag and then boil for four minutes to kill off any nasties. This way I can reduce the weight and the cost.

I'm particularly interested in the water pollution in Dartmoor, as a national park I am assuming that there will be no run off from farms that is common in the UK.

  • Why boil? For under $100 you can buy a modern water filter will allow you to safely drink almost any water. – Carey Gregory Jul 18 '16 at 17:17
  • @carey_gregory weight, reusability and cost, a millbank bag is tiny, weighs nothing, plus I will be boiling water for tea anyway and I have heard that the filters only last a certain number of trips before needing to be replaced – Chris J Jul 18 '16 at 21:18
  • As Liam pointed out in his answer, filters are also a better solution since boiling does nothing to remove most chemicals and heavy metals. – Carey Gregory Jul 19 '16 at 19:53
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I live by Dartmoor and walk there regularly (in fact I was up there earlier today).

The moor carries a significant stock of sheep, cattle and ponies. I've heard of tests that found much of the water is quite heavily contaminated with faeces. In fact the army have used Dartmoor water for testing the effectiveness of filters. The risk is probably quite low, but significantly higher than zero.

So personally I use a good modern bottle filter (known as the TravelTap in the UK, and the Sechelle in the US). It's certified as effective by many agencies, affordable, light, convenient and lasts for years. If you use a bladder, there are inline equivalents. For me it's a no-brainer - there's no significant downside that I can see. Using this filter I've spent hundreds of days on the moor with no issues.

I also avoid water below the larger mines, as I've been told that there's some heavy metal contamination. As much of the place is bog, there's no lack of alternative sources!

I can't see any point to a Millbank bag - the water is running over granite and there's rarely much particulate. Plus a bag costs and weighs almost as much as my filter. Boiling isn't very practical for filling up during the day and requires quite a weight of fuel. You could save yourself a lot of unnecessary faff by using a decent filter!

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Is it safe to drink water from streams in Dartmoor using simple purification methods?

Basically it depends on the water source. Follow some general rules and you should be fine though.

boil for four minutes to kill off any nasties.

bear in mind this won't remove all polutants, something like mercury will not be affected by boiling. A nano filter (like a lifestraw) is actually better at removing contiminants than boiling.

I'm particularly interested in the water pollution in Dartmoor, as a national park I am assuming that there will be no run off from farms that is common in the UK

Dartmoor is (like almost everywhere in the UK) farmed. Actually quite intensivly in international standards. So it's not correct to assume that the water won't contain any run off in dartmoor.

Basically always check the source of the water and what's upstream (physically if possible, using a map is a good backup) before using. You typically want water fed from springs directly (not lakes or ponds) without any hunman contaminants (farm land fertilizers or run off from other man made structures).

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