Seeing as rain is a natural occurrence, it would seem strange to some that capturing and then saving that rainwater would be illegal.
That being said, in some states, while it is not illegal to capture and save rainwater to care for animals or to water plants or crops, it is restricted when it comes to using that saved rainwater for human consumption.
Texas is known for a lot of things, including earthquakes. The most most recent quakes in West Texas don't compare to the largest recorded in the state.