I asked because I'm cautious:
My partner is an experienced renal nurse and has dialysed children with kidney failure for years and seen first hand the very real danger: Their condition is a result of coming into contact with matter contaminated with livestock faeces in the countryside and contracting e.coli. This then means life-long dialysis and possible kidney transplant.
Granted these are children but it's possible for adults to suffer the same, or more likely to pass this unknowingly onto children they are in contact with.
I don't have children, but many of our friends have small babies and my partner has young nieces.
I don't plan on going high enough to be above grazing livestock therefore I'm assuming the water could be contaminated.
I didn't want to start a debate whether one should purify mountain water. I will, and I wanted advice on what equipment to use. To suggest that there are no risks is irresponsible in my opinion, and advising that I should risk it is not sensible when I have expressed concerns already. If you think e.coli is not a risk in the UK I invite you to Yorkhill Children's Hospital in Glasgow to talk with the dozen or so kids currently undergoing kidney dialysis or waiting for a transplant as a result of contracting e.coli.