Easy $5 Water Guns





Introduction: Easy $5 Water Guns

About: I got an old sewing machine when I was just a kid, and I've been hooked on making stuff ever since. My name is Sam and I'm a community manager here at Instructables.

Update! I've got a newer, upgraded water gun instructable right here!

It's a much better design, and easier to make. The original content of this instructable follows:

Recently I found myself needing a whole bunch of water guns. I didn't want to spend a lot of money, and I wanted ones that would be durable and last a long time. I figured my best bet was to just make my own.

I began by looking at a few places online, and right here on instructables for some ideas. I found the water mortar (part one and part two), and the waterzooka instructables very helpful.

With the basic idea of a piston/barrel-type water gun in mind, I wandered around the hardware store for a while until I came up with the following design.

I made a lot of these, and individually the guns ended up costing around $5. It'll cost you more or less depending on a number of things, of course.

They are tons of fun, and we get them out on a regular basis for family water fights. Thanks for looking. I hope you find this useful!

Step 1: Supplies

Conveniently, 1-inch PVC fits quite nicely inside 1 1/4-inch PVC. These sizes of PVC make up the barrel and piston sections of this water gun.

From one 10-foot length of PVC of each of the above mentioned sizes, you can make four 30-inch water guns or six 20-inch guns. The 30-inch guns are best for older kids and adults, whereas the 20-inch guns are easier for little kids to handle. Either way, the design is exactly the same.

This design is pretty simple and easy to mass produce. However, certain parts may be tricky to find. I had to check a couple of hardware stores before I found all the pieces to make this work.

In addition to the pipe, for each gun you will need the following:

  • One 1 1/4" PVC end cap
  • One 3/4" PVC plug
  • One 1 1/2" rubber washer, with inside diameter near 1/4" (and it must be real rubber, not neoprene)
  • One 1 1/4" fender washer, with inside diameter near 1/4"
  • One 1" by 1/2" 90-degree elbow, or similar (see below)
  • One 3/4" #12 pan head screw (or something similar that works)

I say "not neoprene" because common neoprene washers would not work for me. When I put pressure on the piston, water would just shoot out the back of the barrel. One of my local hardware stores carried real rubber washers which were a little stiffer than the neoprene ones, and these worked much better.

There are a couple of options for the 90-degree elbow, which will become the handle. I had plenty of 1/2" PVC scrap, so I got some 1" by 1/2" 90-degree elbows, and attached a small piece of 1/2" PVC to make the handle. You could use a regular elbow, or a cap instead, but I like the look and feel of the 1/2" handle.

Step 2: Barrel

Begin by cutting your barrel and piston pieces. Whatever length you choose, simply cut the barrel and piston pieces exactly the same length.

The 1 1/4-inch end cap needs a hole drilled in the end to become the nozzle. I prefer 1/4" or 3/16". To center the hole, I predrilled a smaller hole from the inside of the cap. (The end of my drill fit nicely into the cap, which centered this little pilot hole almost automatically.) 

Use PVC cement to glue the cap onto the end of the barrel piece. I used sandpaper to knock off the sharp edge of the other end of the barrel.

Step 3: Piston Plug

One of the biggest tricks with this design was figuring out how to quickly and easily seal the end of the 1-inch PVC piston without adding something that was bigger than the pipe itself. The answer was to shave down a 3/4" PVC plug.

This plug is kind of an oddball fitting, so you may have to search a bit for these. They are the same outside diameter as 3/4-inch PVC.

Use a utility knife to carefully shave down the plug so it will fit into the 1" pipe. PVC cement will act as a lubricant to help get the plug in place. Drill a hole in the end of the plug that will tightly fit the screw which will hold the washers in place.

Step 4: Piston Squeegee

The washers are screwed into place at the end of the piston, as shown. I wrapped the screw with teflon tape.

Step 5: Piston Handle

A handle was added to the opposite end of the piston. There are a number of options for this part, as I mentioned before.

Smear a bit of vaseline or other waterproof lubricant inside the barrel before putting the piston in place. This will keep things sliding smoothly.

Step 6: Make a Bunch!

Now make a bunch, and have some crazy water fights with your kids (and all the kids in the neighborhood). When everyone sees how much fun they are, they'll ask you to make them some. Feel free to charge them more than $5 apiece!

To fill the water gun, put the nozzle end under water and draw the piston back to suck water into the barrel. It's important not to draw it back too fast, or to try to shoot the water out too fast either. It takes a couple of tries to figure out the correct amount of pressure to use. 

One last thing... don't store the water guns with the pistons inside the barrels. You don't want the rubber washers to take on any memory.

Good luck!

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    Great water gun; thanks for the plans! These were a big hit on our recent lake stay.
    I've previously made the Waterzooka guns, but like the Easy $5 Water Gun better - this is a more straightforward design with easier to find and fewer parts, and a more manageable size. A couple suggestions/changes I made:

    1. I cut the washers out of an old bike inner tube - they worked great, and I had a plentiful supply at a free to me price.

    2. I tried a few different gun lengths, but liked 20" best - a manageable size with plenty of capacity. Keep in mind the whole thing will essentially double in length when you draw out the piston.

    3. I wrapped electrical tape around the piston about 1" from the nozzle end, giving a warning not to pull the piston out any farther.

    4. I used and liked a "T" fitting on the piston end

    5. We lost 2 guns when they sank in the lake. Cap the ends of the T fitting on the piston to create an air chamber/ block water from entering the piston interior, sinking your gun.

    6. Cut the barrel an inch or two shorter than the piston so that the piston goes all the way to the end of the barrel and expels all the water.

    1 reply

    Thank you for the great tips! I appreciate them and am sure many other people will too. Glad they worked out so well for you.

    I wish I could make one.

    Smart, maybe you should add a water tank for repeated fire.

    I just left lowe's, they have all the parts including pre-cut pvc. problem is finding the correct o'ring. if you type in buna-n on the net a site pops up that has o'rings but I cannot decipher the proper o'ring. if you happen to figure it out shoot me back with a part number or actual dimensions please. still hunting myself and happy hunting to you. rjs1617@yahoo.com

    just wondering is this using schedule 40 pvc or pdr 21 ?

    This one of the best things I've seen on instuctables! Hopefully if I can find the parts I'll make some this summer

    1 reply

    Thanks! I actually suggest taking a look at the waterzooka instructable, especially step #5. I've found that I like the simple building method in that instructable better than what I show here in mine. I made some water guns with O-rings similar to the waterzooka, and they have proven to last longer, and even work better than my version here. (If you can beat 'em, copy 'em!)

    i guess i'll give you credit for this because you posted it first >:( but anyway I was having a water fight with some of my friends and I was running down a sidestreet, and unfortunately dropped my gun and broke it. After QQing for a couple minutes I thought to myself: "what would someone on instructables do?"
    so then (still in instructables mode) grabbed the pump from the end of my broken premade watergun and found a small length of pvc in a neighbors recycling bin
    (shh! don't tell anybody!!) but with the pipe and the pump handle i just needed an endcap... fortunately for me I constantly carry a credit card with duct tape rapped around it, using a pen ink cartridge as a mold I put about a half inch of duct tape around it with a piece of paper in the center (to make the duct tape not stick to the pen cartridge) i took the small duct tape roll with a hole in the center and put in the front of my pvc pipe with the help of some more duct tape and there you have it. an extremely ghetto water gun...

    btw i only said duct tape 4 times and sorry for any grammatical errors

    I did everything you said but I dont get how the finished piston is supposed to fit into the barrel with the 1 and 1/2 inch rubber washer being too big for the 1 and 1/4 inch pipe

    3 replies

    The washer sort of folds down as you push the piston into the barrel. The fact that it's just a little bit bigger than the inside of the barrel is what creates a water tight seal. You will need to put some sort of lubricant in the inside of the barrel (like vaseline) to make it work properly. Let me know if you have any more trouble. I'll try and help if I can.

    This still doesn't work for me after using vaseline. The piston just wont fit into the barrel because the rubber washer is too big. Should I use a 1 and 1/4 inch rubber washer instead?

    Can you take a clear photo of the piston end along with opening of the barrel for me? Post it here, and I'll see if that gives me a better idea of what the problem could be.

    oh mines way to small. i was wondering why u shaved it. lol

    my plug dosent fit snug it dosent even touch it. can u help or is that normal?

    3 replies

    If it's too small you'll have to buy a bigger size.

    ok. but does yours fit tight?

    If we're talking about the plug that goes in the end of the piston--yes, it fits extremely tight. It's actually too big to begin with. That's why I have to shave them down as I show in step 3.

    Awesome tutorial! Can't wait to make these with my husband. Any ideas on painting them? I thought Camo would be fun but wondering if the paint would just come off on the user's hands.

    1 reply

    I'd use spray paint. It might wear off after time, but I think it would stick pretty well.