In my line of work, bacterial fermentation, I have used bladders
close to what you are asking for. I know this is not going to help
much, they are not easy to find, but Stedim makes bladders
("flexboys") in various sizes. In the smaller sizes (0.5 - 50 liters)
they look just like IV bags.

A whole range of connectors, pharmaceutical kind, for your convenience.

Sure would would look good having a 20 l "IV bag" under the van.

Alistair

'82 westy, diesel converted to gas in '94
http://www.members.shaw.ca/albell/

On 29-May-07, at 3:49 PM, Mike Rocket J Squirrel Elliott wrote:

I've been using a little 2-1/2 gallon collapsible jug under Mellow
Yellow to catch sink drainage. http://tinyurl.com/yryy6u is the item. I
have a foot-long piece of garden hose that screws to the drain outlet
and dangles into the jug. Problem is, in gusty winds, when the thing is
empty or mostly so, it can blow away or at least slide enough so that
the hose pulls out. In our neck of the woods, letting your gray water
spill all over the pad where the vehicle is meant to be kept is
considered bad form. I was thinking that there might be something
flatter -- like a bladder of some sort -- that could hold the gray
water. I've found plenty of gray and potable water bladders -- in the
100 gallon and up size. Anyone know of small bladders that might accept
a garden hose or similar?
--

Mike "Rocket J Squirrel" Elliott
71 Type 2: the Wonderbus
84 Westfalia: Mellow Yellow ("The Electrical Banana")
74 Utility Trailer. Ladybug Trailer, Inc., San Juan Capistrano
KG6RCR