You can probably come up with some type of dimensionless number (if one does not already exist) that may help to determine when a stream will break into droplets. For example, the Reynolds number is the ratio of inertial forces to viscous forces and is used to determine if a certain fluid flow is laminar or turbulent. In your case, it is necessary to determine why the stream breaks up into droplets. The more I think about it, the Reynolds number might work.
The Mythbusters did an experiment where they simulated a dummy peeing on a subway rail. The dummy was connected to a volt meter. The breaking up of the stream into droplets was very effective at creating discontinuity and preventing the dummy from receiving a shock. They had to get the source of the stream very close to the rail to before the dummy felt anything.