My fellow Rotarians, and any other that would dare fly behind the
Triangle of Cast-Iron, I submit for your perusal and intrepid
consideration what may very well be the lightest, the cheapest, and,
dare I say, the easiest Wye fitting and backflow preventer yet presented
in these fair halls.  After much consideration, soul searching, and
homemade spirits, this device was designed and constructed in a single
evening session by your humble servant.  Fashioned from lightweight
aluminum components, available off the shelf in many well stocked
venues, I choose now to provide you with instruction and necessary
elocution that will make it possible for you to experience the pleasure
of constructing such a simple, albeit functional, device.

The primary parts were ordered at once from one McMaster Carr.  The
order consisted of:
- two 3/4" hose barb fittings for $6.84 each
- two 1" to 3/4" couplers at $3.80 each
- a 1" Tee, for $8.98
- and a single 1" hose barb for $6.84
The remainder of the  materials consisted of a scrap of .100 aluminum, a
4" lenght of 1/4" threaded rod, two nuts, two washers, and a little heat
shrink; all free material as surely intrepid builders and inventors such
as ourselves have this sort of crap lying all over the place.

A 1-1/2" hole saw with a 1/4" guiding bit was first used to obtain a
disk of the aluminum scrap.  The sides must be flattened so that it will
slide into the center of the T.  Spin a nut halfway down the rod, add a
washer, then slip it into the plate through one arm of the Tee.   Apply
the other washer and nut from the other arm, and squeeze the plate in
the middle.  A wrench through the leg of the Tee, and a deep well socket
through one of the arms is the prescription for the necessary locking
force.  Heat shrink the rod extensions to both protect the inside of the
aluminum fittings and to smooth the water flow.  What you will have for
your slight trouble, is a 17oz device that will automatically keep insy
water from flowing through the outsy port.