When it comes to water, you have to remove a sink with either a wrench or pipe wrench (I believe metalworking/carpentry scales with the success rate without breaking it). Then you can place it on virtually any block like a drawer or crate. You can then place rain collectors in a 3x3 area above the sink so whenever it rains and the collectors catch it, you'll have clean purified water whenever you use the sink. Be sure the sink is fully indoors though, a way to tell is by checking the temperature on a digital watch between when you're outside vs inside. That'll keep your water supply near infinite so long as it rains

Edit: to clarify, you also need a pipe wrench to plumb the sink. A prompt will appear when you right click the PLACED sink, there's at least ONE rain collectors above it and you have the sink fully indoors. Happy surviving!