Build a simple stand near the inlet point of your drip system by fitting and stacking the cinder blocks. The stand should be stable, level and slightly larger than the bottom diameter of the barrel. The stand should elevate the bottom of the water barrel at least four feet above the highest point in the garden. Greater elevation delivers greater water pressure to your irrigation system. If elevation is too little, it will not work.
Drill a 1-inch-diameter hole through the wall of the plastic drum, 2 inches above its floor.
Use the hacksaw to cut a piece of 1-inch PVC pipe 2 1/8 inches long and paint it with the PVC primer. Repeat this twice, so that you have three pieces of 1-inch PVC.
Prime on the inside of the 1-inch connector and let dry, then use the PVC glue to attach it to one of your 3-inch pieces of PVC. For best results, put glue on both surfaces.
Push a rubber washer onto the piece of pipe until it rests against the connector you glued on and, from the inside of the barrel, push the pipe through the hole you drilled. The connector and washer should now be on the inside of the barrel; press the washer against the edge of the hole.
Ask your helper to hold the interior assembly firmly against the inside of the barrel, while you push a washer onto the piece of pipe from the outside of the barrel and glue the elbow connector onto the outside end of the pipe. Hold the elbow firmly against the washer until the glue dries to ensure a tight fit and point the outlet end of the elbow straight down in relation to the barrel.
Prime and glue another piece of 1-inch pipe into the outlet end of the elbow.
Prime the inside of the in-line valve and glue it to the other end of the piece of PVC.
Glue the third piece of cut PVC into the bottom end of the in-line valve.
Position the barrel on the stand you made for it. The assembly you made now extends downward below the bottom of the barrel and should be facing the garden you plan to irrigate.
Measure and cut a piece of the plastic tubing adequate to reach from the valve assembly to the inlet tube for the drip system and use a hose clamp to attach it to the bottom piece of PVC.
Attach the other end to your irrigation system inlet hose.
Fill the barrel with water.
Turn the valve to the open position to water your garden.