Water sources on the BGR
Given how much water falls on the Lake District, the BGR crosses remarkably few water courses. There are boggy sections but even when desperate, few would want to drink from them. This is a list of the main watering holes you can expect to find during most summers.
Water Quality
Whether you drink from fell streams or becks is down to personal preference. However, some may not be used to drinking untreated water, some may not fancy the idea. Although tales have circulated for many years about an increase in waterborne diseases such as Giardia, I have not heard of a single case attributed to drinking water from Lakeland becks or tarns that has been substantiated.
Obviously you would not drink directly downstream of a rotting sheep carcase, but providing that the water is running and clear, I personally would not be worried about drinking from any Lakeland beck.
The sources
Skiddaw Section
GR283303 A largish beck by the side of the track to Skiddaw House.
GR296297 The River Caldew between Great Calva and Blencathra.
Helvellyn Section
GR-338151 Brownrigg Well. A fresh water spring around 50m below the col between Helvellyn and Lower Man. This is the only recommendable source on the Helvellyn ridge.
GR-351121 The outflow from Grizedale Tarn though this is not on the route used in the notes.
Central Section
Mere Beck which extends from GR-293100 to GR-292096
GR-278072 This is at the head of Dungeon Gill. At your own risk!!
GR-260081 Stake Gill at the point where it drops out of Langdale Combe.
Angle tarn is close but not on-route
There is a beck with clear water on the approach to the ramps up Bowfell. I do not know how reliable it is in dry summers.
About 200m further on the Scafell track from where you leave for Great End the path crosses a clear beck. This is the last reliable water on this section.
About 200m SSW from Scafell Pike lies Broadcrag Tarn This is off-route but is fairly easy to get to. In very hot weather the water may be a bit stagnant.
Wasdale Section
Black Sail Pass. There is a good spring on the Wasdale side a short distance down from the col.
Robinson Section
GR-215178 Scope Beck but it is very close to the road.
Other stretches of water may be found but not all can be relied upon. There are also rivers and becks close to section ends (Dunmail and Wasdale) but these are of little use overall, save perhaps to soothe sore feet.