Step 3: Setting Up the Tank
To make a tank outlet, cut a 1-5/8" hole in the tank wall with the hole saw (or very carefully cut a circle of that diameter with a utility knife). Cut the bottom outlet hole near the bottom of the tank, but high enough to allow all of the hardware to fit (especially the metal nut on the inside). For the safety outlet, cut another 1 5/8" hole in the top of the tank wall, again, leaving space for the hardware at the top.
Slide one of the rubber washers over the male end of the PVC threaded adapter. Insert that end through the hole from the tank exterior. Slide another rubber washer over the male end and then screw on a metal 1-1/2" thread washer over it. From outside to inside you should now have the following order of parts: The outer lip of the adapter, washer, tank wall, washer, metal nut. The two accompanying photos show views of the outside and inside of an outlet. The inside view shows a store-bought rubber washer and the outside view shows a washer made from a piece of tire inner tube.
Next, tighten the metal nut as much as you can by hand, and then use to two pipe wrenches to finish tightening it up. This step is easier with two people. One holds the outside of the adapter fixed with one pipe wrench, while the other person tightens the nut inside the tank. It is possible to tighten the nut too much, and deform or tear the washer.
Next attach, the outlet hose. Here, a secondPVC adapter is threaded into the outlet female thread, with teflon tape between the threads. Finally, slide the connecting end of a length of 1-1/4" corrugated hose over the adapter and tighten with a hose clamp (3rd photo below).
When not in use, the hose should be fastened so its end is at or above the top of the tank, otherwise water will leak out. The 4th photo below shows how I did this. I have a threaded hook passing through the tank wall and tightened with a nut. The hose has a piece of flexible wire wrapped around it and hanging from the hook (twist tie material will work as well).
Do a leak check by filling the tank with a few inches of water. If water leaks anywhere, some trial and error with tightening or loosening the metal nut should fix the problem. Being leak proof is much more important for the bottom outlet, because that one will be used all of the time and will also be under pressure. The top outlet will probably work OK even if it is not a perfect seal.