Rain Water Downspout Diverter

I purchased two 80 gallon rocks as I call them, 80 Gallon Waterstone Rainwater Collection System as Emsco calls them, but didn't particularly like the included rain spout diverter. I looked around and found a number of diverters in the $30 price range, somewhat reasonable in my book, but could not find any place that carried any locally and I did not want to wait to have it shipped to me. So I decided to explore making my own.

So I visited my local ACE Hardware store where I remembered seeing a PVC 2"x3" downspout to 4" pipe adapter. My initial thought was to use two of these adapter, one for the inlet and one for the outlet but doing so posed a problem. These adapters are designed for use as an inlet so that left no easy, decent way to connect them to the same size 2"x3" downspout with a good seal. Gooping in tons of Silicone Sealer was out of the question. And also, adding a deflector as a spillover (this will become clear later) would not have been as easy as it turned out by using a 4" pipe cap as the bottom half instead.
(Click on any picture to enlarge it)
Rainspout Diverter   Rainspout Diverter
The parts, from left to right.

Top row
2"x3" Downspout to 4" Pipe Adapter (Schedule 80)
4" Dia. x 3-1/2" Len. Pipe (Schedule 80)
4" Pipe Cap (Schedule 80)

Bottom row
3/4" Slip x FPT Elbow (Schedule 40)
3/4" Pipe to 1/2" Pipe Reducer (Schedule 40)
1-1/2" Long Pipe Coupling (Schedule 40)
1-1/2" Short Pipe Coupling (Schedule 40)
4" Pipe Cap (Schedule 80)

Not Shown
1-1/2" Dia. x 1-1/2" Len. Pipe (Schedule 40)
Rainspout Diverter   Rainspout Diverter
First glue the end cap onto the 3-1/2" piece of 4" PVC pipe. Then once the glue has set drill two holes in the end cap. The larger hole is for the 1-1/2" PVC pipe and in just large enough for the pipe to slide through tightly. Position the hole far enough in from the edge so that the shorter of the two couplings will line up with the 1-1/2" pipe when the coupling is on the inside of the 4" PVC pipe sitting on the end cap. The smaller hole is for the 3/4" to 1/2" reducer, again size the hole so that the reducer slides through tightly and space the hole far enough from the edge so that the reducers lip fits from the inside of the end cap.
Rainspout Diverter
Now glue the 1-1/2" piece of 1-1/2" PVC pipe to the shorter of the two 1-1/2" couplings. Then place that assembly from the inside of the end cap through the larger hole in end cap and glue the longer of the two 1-1/2" coupling to the 1-1/2" PVC pipe sticking through the end cap and clamp the assembly until glue has set.
Rainspout Diverter   Rainspout Diverter
Next glue on the 3/4" elbow by applying glue to the outside of the 3/4" to 1/2" reducer and to the smaller hole in the end cap. Then slide the reducer through the hole in the end cap from the inside of the end cap. Apply more glue to the reducer that is now sticking out of the end cap and to the inside of the elbow and assemble as shown. (Position the elbow in the direction you want.) Hold or clamp the assembley until the glue has set.
Rainspout Diverter   Rainspout Diverter   Rainspout Diverter
Next install the deflector. Make the deflector from the second 4" end cap by cutting away the sides so that only the end disk remains. Then saw a slit in the 4" pipe directly above the 1-1/2" coupling, half way (in the middle) of the section of the 4" PVC pipe that is extending out of the glued on end cap, approximately 1/3 of the way through the 4" PVC pipe.

Slide the disk that was created from the second end cap into that slit sawed in the 4" PVC pipe just far enough so that it completely covers the 1-1/2" coupling. Scribe a line on the disk following the outside diameter of the 4" PVC pipe then cut the disk to that line forming an "eye" shape. Glue this eye shaped piece of the disk into the slit sawed in the 4" PVC pipe making sure the eye disk is flush with the outside of the 4" PVC pipe.
Rainspout Diverter   Rainspout Diverter
Lastly glue on the 2"x3" downspout to 4" PVC pipe adapter to the 4" PVC pipe already glued to the end cap positioning the 2"x3" opening directly over the deflector plate thus over and in line with the 1-1/2" couplings that act as the overflow discharge outlet.
Rainspout Diverter   Rainspout Diverter
The completed diverter and a picture of it installed.