I've found a backpack with a space for a bladder, the bag is only £16, so how much do i have to spend on a bladder, and which size shall i get?
Cheers,

I found an excellent deal in (dare I admit it) Lidl. They had various size rucksacks, with bladders for £10. There were a 1.5 and 2.5 litre version, both at the same price. If you buy a Camel Back bladder you'll be looking at £15.

when was that?

Also what sze did you go for?

It was about a month ago, apparently they have these offers on every now and again.
I went for the 1.5 litre which seems to be enough: It's the equivalent of 2 water bottles.
I ran it dry over the weekend but we did Jacob's Ladder in Edale which is 18 miles and 3500ft climb so quite thirsty work.
You always have the water bottle as a reserve.

I wouldn't go for a bladder any less then 1.5litres and if you get a larger one, assuming it will ift in your backpack, you don't have to fill it right up

A 2 ltr Platypus Hoser is about £15 but well worth the money.
They are freezable, boilable and very much bomb proof.
Heaps better than the bladders you get with Camelbaks and the like!

camelbacs are quite expensive IMO, hydrapak are better value, unless you get a camelbac in an offer. i got my 2 litre for £15.

got a £17 bag from Blacks and a platypus bladder (1.8 L) i think that will be plenty big enough, all for only £31!

you ca have mine for free if your a surgeon its quite weak though.
1 not very careful owner