33gal freshwater, about how long will it last?

thanks for the advice. i was planning on having a couple 5 gallon backups the first few times, til we get an idea of what our usage is like. the tips for conserving (both fresh water and space in the gray water tank) are certainly helpful for beginners. im sure there are others who are just starting out and these types of topics are always good info! i suppose a better topic title might be "stretching every drop" and other advice for saving water/tank space etc.