Water catchment Just makes sense, provided it is legal in your area. Believe it or not, some places do regulate rainwater and it may be illegal for you to harvest it for your own benefits. Of course, in a Without Rule Of Law situation that would be the least of the authority's worries.

Assuming it's legal, harvest as much rainwater as you can. This can be purified/filtered later for use drinking or to clean clothes. Even unfiltered it has tons of uses; water your garden, water your livestock, use in aquaculture, or even use it in an emergency to flush your toilets (for a while).

Pictured is a musical water catch. Don't just think useful, make it aesthetically pleasing. Take pride in your work.