I buried it a bit but so far my favored provision for carrying water in my kit are the Platypus bottles.
http://www.platypushydration.com/product_detail.aspx?ProdID=36They are tough, compact and reliable. If and when they get a pinhole after a lot of rough use they are repairable. Even after many trips under lousy conditions and with little to no pampering none of my Platypus bottles have had to be retired. The patches are cheap, light and compact. I usually slip one or two into my wallet on trips.
I keep two rolled up half-liter ones in my small PSK and two liter size ones in the larger kit. For hiking the bladders and canteens see use but these Platypus bottles. Note that the screw-on caps are a bit lighter and more compact than the pop-up tops but they have to be completely removed to drink and so they more subject to loss. In my larger kit I use one pop-up and one screw -on. With a screw-on as a spare. A bottle without a cap is pretty useless.
This is also one of my main complaints on using condoms or oven bags or zip-locks. The closures are not very good or easy to use.
This company also sells larger carrier bags and bladders. I haven't used one but they are said to be good. When my present set of bladders and canteens give up I will be looking closely at what Platypus has for replacements.
Tip - If you take a screw on cap and drill a 1/16" hole in the center and screw it on a half-liter collapsible bottle you have a nice device for irrigating open wounds. You can also do it with a zip-lock but these tri-laminate bottles can take more pressure and be reused many times. I colored the drilled cap with a red marker so it doesn't get confused with the others and also keep one without the hole handy. All three pieces ride in my first-aid kit.