Julian Cope presents Head Heritage

"my favourites are the famous ones - Swallowhead Spring near WKLB, which should start flowing about now. And the Red (iron ore) and White Springs at Glastonbury."

I find the modern 'offerings' at Swallowhead slightly disturbing, though I love the old willow. It probably has first dibs as being from the Neolithic age that you can almost justify ;)
When springs become red, either through minerals, or other reasons, I suspect they may have a 'sacred' element in them. Believe the River Chew by Stanton Drew stone circle turns red and there is another well, outside Keynsham which turns red as well, probably through the story of the blood of the saint who was killed there...