In reply to Percy: I've got the inov8 bladder thing but tbh I don't like it that much and the bum bag that goes with it is far too big for wee runs out on the hill (maybe better for winter or longer trips out when you may need to carry more)
Like one of the posters said above, if it's just a short run up to 10 miles then I wouldn't bother with water. Unless I'm out on a totally scorchio day and then I find I need to drink or I get really dehydrated and end up with a stonking headache if I run. Even then though, that bladder can hold up to 2L of water and that's WAY too much, I'd only ever drink that much water on the hill if I was in the Alps or somethings, or out for a 12hr day on the Scottish hills in the height of summer (and only then if it were really sunny)
So when I first got the bladder I didn't even fully fill it so it's taking up unecassary space and weight (and I didn't even use it that much anyway.)
It's easy to drink from on the go, I just tuck the hose into the strap around my waist. Also, it's a total hassle to empty properly and though I've not actually cleaned mine yet, it looks problematic to clean also. Personally, if I were to buy again, then I'd stay clear of the bladder and just go for a small bottle instead.
But bumbag everytime, bags are horrible to run with.