Living off the grid is becoming a more and more popular movement. How far you are willing to go to become self sustaining is only limited by your imagination and your wallet.
Running water is probably one of the modern conveniences that would be hardest to live without, but how can this be solved in a safe, practical way? Some have chosen to install a rainwater catchment system.
This is something that has been done for centuries, sometimes for something as simple as water to use for watering crops. However, if you want to use water collected for drinking, it will need to be treated. You should consider the surface on which the water collects to make sure that it is clean and free of dangerous chemicals.
If you just want to use the water for cleaning clothes and flushing toilets, you won’t need to be as concerned with the quality of the water, but it might still need a filter to keep debris and larger particles out of your plumbing system.