This abomination was made for a 24-hour bike marathon to make drinking easier. Normally I would just stop and take a bottle from the underseat bag, but frequent stopping is not a good idea during a race.
I wanted the bag to be free for food, clothes and tools, so water had to go to the rear rack right behind my head. First try was a standard Kellys two-litre bladder with a hose, but even with the how-to-mount-it-there problem solved (military sack and a rubber cord; standard rack bags are too small), it was foiled by leaking hose. It has to be tightened precisely between "still leaking" and "skipped a thread and leaking again", which is impossible to achieve during the ride (conclusion: no more threaded hoses).
Smartube system (or whatever it's called) seems ideal: a hose with a lid you can screw on any plastic bottle. But it was nowhere to find and the race day was approaching. So a quick improvisation took place.
The tank is a two-litre PET bottle. Drinking hose goes through a hole in the lid, together with a pressure relief straw. The holes are sealed with a FixAll universal plumbing glue (it's said to not hold on PE and PP, but it's enough for this low-strength joint). Inner end of the hose bends to the bottom by its own weight. The straw is bent so that its both ends are above the water level. The bottle is placed on a styrofoam base and duct-taped to the rack. The lid is at the rear because the headrest is in the way at the front and because the pointy rear end looks pretty aero :-). The hose runs through the styrofoam under the bottle, continues over right shoulder of the pilot and ends in his left shirt pocket. A laundry peg substitutes a valve. All traces of rubbery taste flushed out quickly, the glue seems to be safe.
Because the lid can't be easily unscrewed, the tank can only be filled through the hose. I modified a plastic funnel so that the hose fits in it (it's generally not a good idea to mix hot glue with food and beverages, but here it doesn't contact the water long enough to do any harm). After several minutes of refuelling jet fighter act I'm ready to go.
There are no effects on the bike handling. I was worried the splashing water could compromise stability, but no such thing happened. Two hands are needed to unpeg the hose, but that's no problem on a hands-free Python.
Main goal was accomplished: the drinking works, even though it's a long way behind factory-made products. A bad idea was to put bare duct tape near my fluttering long hair =:-).
I don't use this bottle anymore. It was replaced by Source two-litre bladder with no leakage problems, stored in a small rigid bag on top of the rack. Not so original, but much more practical.