Here is the hydration pack that I have been using for the last few Tough Mudder events I've done. This is an old prototype from Platatac that I picked up on eBay, and combines elements of both their Bravo hydration carrier that I have, and the MEOP Medic Pack both of which I've covered in the past, and are great pieces.
I found that wearing an extra set of straps was redundant when I was wearing a vest anyway on my Tough Mudder and similar adventures, which is why I looked for an alternative to the Bravo, which has served me well in other situations, and on my first Tough Mudder. When I saw this piece come up on eBay, I was thrilled to give it a go. It follows the same kind of design philosophy I've come to expect from Platatac pieces, with a tough 1000d Cordura exterior, and ITW Nexus hardware. It if "faced" with 6 rows of 4 channel PALLS/MOLLE loops, and features a hook-and-loop secured drag handle. Running down the flanks are nylon D-rings, three to a side, allowing shock or paracord to be run through these, to provide attachment points, or compression.
The wide-mouth of the pouch perfectly fits the Source Storm 3L hydration bladders main cap.
The baffled sides of the carrier allow for quite significant volumes to be carrier, without restriction, or perhaps even storage for other items besides a hydration pack. However, this particular piece lack the zipper-access of the Bravo, which means that the only access into or out of the inside is through the main cap.
This actually posed a problem when trying to run my hydration hose through it, and I bit the bullet and melted a channel in the backside to feed it through.
I also had to melt a drainage hole in the bottom, following the previous Tough Mudder, last September.
I found that the carrier filled up with nasty pond water when I took my tumbles, which really added to the weight I was hauling. No such trouble with a small drain hole melted in this time around.
The back of the carrier offers a variety of attachment options; Zippers paired with the MEOP carrier (which allows me to sandwich these two pouches nicely). It also features female Fastex clip ends top and bottom, tri-glide loops for all your clipping and looping needs. Best yet, the back features two sets of three three channel PALS/MOLLE PLMRS (Platypus Light Modular Recovery System) strips. These gave both a rock solid attachment and also load spreading capacity. I barely felt the 3kg that the full bladder weighed,and certainly not the sloshing side-to-side I might have with a pack-type carrier.
This was just a prototype, bridging the gap between the Bravo and the MEOP, but if you want to see the new production version, check out the Platatac Utility Hydration Cover. Looks like the logical next step.