Another great project form the King of Random https://www.google.com/?gws_rd=ssl#q=king+of+random+water+pump that I built at the farm. I am making some notes to go with The King's video that hopefully will assist you. I really need to find a good plumbing supply because my access to 1¼" PVC fittings is limited. Design #2 will be made with screwed fittings. Note that this pump could be also used as an air pump to blow up air mattresses on a camping trip. A slight addition to the discharge side to connect to the mattress and you should be good to go.

The first problem I had was finding rubber balls the correct size. I found some slightly larger which required a design modification. Also had some trouble finding O-rings that were the right size. On the suction side I used a 1¼" to 1" threaded reducer. the inside has a nice bevel to it which I thought would make a great seat for the rubber ball. It does, but the pump creates so much pressure the ball actually sucks inside the fitting and had to be manually pushed out. The nail distance to hold the ball in place is critical. I got the suction side to fare back and had to modify it later. You want just enough movement for water flow.

Had a rough time drilling the cap for the plunger. Two problems: First, getting it exactly centered. Second, none of my bits are the exact size needed. So I got the hole to large and the O-ring keeps popping out. Next time I will under drill the hole and use a spindle saner to get a snug fit. Never did find a plug that would fit inside of the 1" pipe for the plunger so I sanded down a ¾" plug and used lots of glue. It really does not have much pressure on it so it works fine.

This thing puts out a hell of a lot of water in a very short time. Just about a quart per stroke so if you are really pushing it that equates to about 5 gal in 20 seconds ±.