This is a great little tip for saving money on hand soap.
Buy a couple of the foamy soap bottles and a bulk bag of hand soap at you local Target or grocery store as an initial investment. Once you've used up what's in the bottles, refill the dispensers with 1/3 soap and 2/3 water. And shake em all around.
If you're children tend to pour out entire bottles behind your back as mine do, then you will be so glad that you DIY'd and did not pay all that money for essentially water.
Idea found here.