May 20, 20114 found this helpful
We held a water balloon party for my 12 year old Granddaughter. It was a huge hit with girls and boys alike. She invited her entire class and all but one came (just mention water balloons a kid will be there ;-)). You can buy water balloons cheaply at Walmart or purchase them online. We spread a giant superslide across the lawn to place all the water balloons on, we also purchased two small blow-up kid pools to store the balloons in (tip: don't stack them more than three balloons high or they will burst by themselves from the pressure). We attempted to play organized games with the balloons, but since these kids were middle school age, they had much more fun left on their own to have a huge water balloon fight (the only rule we had was no hitting in the face). The only thing I had to purchase was the water balloons, cake, ice cream, and streamers (I already had the blowup pools and superslide; if you don't have those call around and borrow them from friends/family). The cost of this type party is very inexpensive BUT there is a lot of planning and work involved. It is better to have all the water balloon filled before the party begins. My boyfriend and I started filling the water balloons two days before the party. Once you have filled the first hundred balloons you start to get faster at filling them, we ended up with 2300 water balloons for the party and 15 kids popped every one of them within an hour.
One last thing, I recommend having a little game in the end. Whichever kid picks up the most popped balloons from the grass gets $10 (otherwise your yard will be filled with little balloon pieces and it's not good for the birds to eat).