Rubbermaid Stock Tank Adaptor

This is how I plumb rubbermaid stock tanks. The bulkhead is 1.25 female NPT pipe thread on the outside and the useless back side of these threads in the inside.

The solution is to take a 1.25 male adapter and use a dremel and a sanding bit to bore out it to the point where a one inch pipe will pass through. Glue the one inch pipe into place with a couple inches inside the tank to attach the stand pipe to. It can the flush on the outside and plumb te drain to the 1.25 male adapter or have it sticking out as shown for 1 inch plumbing. All stand pipe is simple friction fit.