Many people feel that an adequate supply of clean water will be one of the most significant issues of the future, and I have no reason to doubt that. The United States has been blessed with an abundance of good water, and we have gotten used to having it at the twist of a faucet handle. It can be a shock when water supplies diminish and water has to be rationed, or if the supply gets contaminated and is no longer available for potable use.
Water agencies always advise conservation; they know how precious and limited the supply is. In fact, many plumbing codes now require that new installations of toilets be low consumption models and that showers be fitted with restriction diaphragms to limit the flow of water.
Other strategies for conserving domestic water tend to be rather controversial. The reuse of gray water, using rain water catchment systems and composting toilets all conserve water but may be frowned upon for various reasons, mostly to do with health concerns. In many places these practices are flat out illegal, even though they have been shown to be safe and effective when utilized carefully.