There is little need to ask how water is misused, it just is, and quite easily with or without one's knowledge of it. With so many uses for it, there are that many more applications that could shelter inefficiencies that would lead to waste. Even the simple and careless act of overuse can be considered a misuse. To use water properly and at its highest level of efficiency is the best way to save water, but it is difficult to understand where to start and how to attract attention.
The main problem associated with water use is the complete lack of numerical assignment that would gather attention. It is unfortunate, but humanity seems only sensible when something carries with it a monetary tie, that is, if people can not actually see the value assigned to it they tend not to recognize it. That's just the way it is. Things might be different if there was a digital display that tracked the volume used in a day compared to national and international trends that may make one more conscientious. If that wouldn't work, then a pay-per-use system that let's people see how valuable water really is after it all adds up. If that was the new way of the world, what changes might be seen?
In this theoretical world where water use is tracked visually, the first place change may occur would be in the bathroom. Although people really love long showers, just how much water are they letting go down the drain after a too brief period of use when that same shower could fill how many bathtubs? If the objective is to simply take the dirt off, a shower can be over in a few minutes, but if it is a drawn out process, the bath may be the better way to go. Less use is not a misuse.
Washing the car for long periods of time, multiple times a week would be discouraged. It might be cheaper at the car wash by letting someone else manage how much water is used. A similar thing could be said for hand washing dishes and some clothes, though more times than not machines are involved these days.
The big water wasters, those in agriculture, would have to reconsider their irrigation tendencies by thinking of ways to keep the water in the soil or recovering evaporation. If the plants don't get the water, that is like throwing money into the wind. Some of it may return, but the rest is never seen again.
From there on, there are any number of ways water can be overused and wasted when it may have been avoided altogether. What people have to do to prevent water misuse is to simply be aware of their use and for what purpose it serves. Stricter regulations and usage limits would help conserve, but it shouldn't have to be necessary. If people learn to be wise with water use, they can slowly abate the problem until a solution is found.