I don't know why they say it is a problem. I'd be more concerned about trapped water taking up more space in garbage trucks, landfill, etc. Even then, the extra cost may be small. My take is that (1) the preciousness of water depends heavily on location and (2) a small number of activities represent the vast majority of water use. In some places there is loads of rainfall and if shortages happen, they could maybe just be solved by improving infrastructure (more reservoirs and treatment plants). Places with a large population for the amount of water available (possibly including Texas, I don't know) need to be more sparing with their water. Often most water, especially in arid places, tends to go to plant cultivation. That includes crops (for human or animal consumption), parks & golf courses, back yards etc. If you want to save water, that is where most of the gains can be made. Turning off the tap/faucet while you brush your teeth is nice but it won't do much.