I'm getting ready for a tour of Big Bend Park in S. Texas. Water is a definite concern.

I have 4 btl cages on the bent, but feel I need 2-4 liters more. Will be no room left in panniers for extra bottles.

I'm looking for a bladder that will fit/hang behind the webbed seat of my bent, in a space 2" deep and about 14" wide. And I don't want to pay more than about $10-15 for it, as it'll be a one time use.

Anybody got any ideas/experience for/with an inexpensive, reliable bladder? A DIY?

Go to the camping section of Walmart. They have Outdoor Products replacement bladders for $8 (I think the insulated bladders go for $15). I have a couple. I ginked the first one, causing the bite-valve to drip a little bit, but they have replacement valves for $2 or $3 (two in a pack).

We have had good luck with a Platypus bladder. They are a little spendy, but very tough. They also take very little room when empty.
https://www.mountaingear.com/webstore.../R-113645P.htm

Also consider the MSR Dromedary bags. I have the 4 liter but wish I bought the 10 liter. Very durable with plenty of accessories.
https://www.rei.com/product/733948/ms...y-bag-10-liter

No experience with a bladder here, however you may wish to consider a larger water bottle cage. The Salsa Anything cage for example. https://salsacycles.com/components/anything_cage/ scroll to towards the bottom of the page.

I use a Camelback Unbottle in the very same position on my Rans Vrex recumbent. I have both the 2 & 3 liters. It fits perfectly in there and the tough outer cover protects the bladder

I like that one too. The capacity is about right for me and it stands up nicely. Two liters is plenty for me for in camp.

I am kind of surprised at the comments about so many bottles on the bike and such large water bladders. I have always found two bottle cages sufficient, because I am ready for a quick stop before both are empty any way. At that point I can refill them from whatever extra I am carrying. As far as carrying capacity, it makes more sense to me to add and reduce capacity by saving or discarding sport drink bottles than to carry a bunch of empty capacity all of the time. Water bottles in the cages get hotter than water bottles in the pannier.

I managed to pick up a couple 2L water bags for 7.50 each at MEC. Very small and lightweight.

+1. I carry two water bottles and 48 ounce bladder that I fill late in the day prior to camping in areas without water. When I toured through Big Bend, and camped in the desert, I supplemented my supply with sport drink bottles as above.

If you're looking for a larger bladder I'd recommend this. I prefer the large mouth for easier filling, cleaning, adding ice, and to use with filters. My 48 ounce has lasted for many years.

Thanks for the ideas. Wouldn't mind investing in a high end bag(the MSRs?), but figure this to be a one time need, maybe. Not much of a boonies tourist. Being led astray by a buddy who is.

As it turned out, another buddy has three 2 liter Platypus bags he'll loan. Found out after posting the question.

I used (4) 10 liter MSR dromedary bags for a kayak tour recently and I would highly recommend them. I was throwing them around for two months and never got a leak. Maybe get (2) 4 liter bags to even it out and you are set for years.

I noticed that some 'bent manufacturers offer custom hydration systems that fit nicely on their frames. Have you checked with yours?