Most US citizens who want to setup a rainwater harvesting system in their backyard can do so without the fear of legal consequence. The Federal Government does not have any restrictions on rainwater harvesting. Some states have minor regulations in terms of the amount of rainwater collecting and the means by which it is collected, but most states allow their citizens to collect rainwater while others even encourage it.

Some government restriction on rainwater harvesting is based on the rationale that it may disrupt the hydrologic cycle. It's been believed that the collection of rainwater would halt the rainfall’s natural flow into the earth’s aquifers and streams. However, a study published by the Scientific World Journal shows that the amount of rainwater collected by individual homes would have little to no effect on the hydrologic cycle on a macro-level. In fact, since most collected rainwater would be used for gardening and household purposes, the water would eventually be returned to the ground anyway.

Other reasons for government restriction are based on old laws known as prior appropriation, which were implemented as a first-come, first-serve basis for settlers in the Old West.

Organizations such as the American Rainwater Catchment Systems Association (ARCSA) work with state governments in making rainwater collection an available option for its citizens.

Most states have shifted their laws in favor of private rainwater harvesting. Colorado, the state with arguably the strictest rainwater harvesting laws, passed a bill in 2016 allowing for the collection of rainwater with a 110-gallon maximum capacity. At this rate, it is likely that most states will trend towards favoring rainwater collection, and it is highly unlikely that the federal government will enforce any restriction.