The electrical effects developed by Lenard splashing near waterfalls, under laboratory conditions, and within the closed environments of a bathroom and a cargo tank of an oil supertanker during seawater washing operations, show a consistent phenomenology. Both theory and experimental evidence suggest that electrical conditions in the closed container atmospheres are defined by In this equation, N is the number density of large charged carriers (large ions and haze droplets), t is time, and e the electronic charge. The rate of charge production, Q, is approximately -10-12 coulomb per gram for the bathroom water and +10−11 coulomb per gram for the seawater. These values correspond to number densities of some 105 per cm3 and space-charge densities of ∓ 10-8 coulomb per m3. The field within a closed container is approximately proportional to the product of the linear container dimension and the space-charge density.Conditions within an oil supertanker cargo tank during the washing operations are considered. It is concluded that the electrification is sufficiently intense for a large-scale spark streamer to have a good chance of developing. This chance--and therefore the explosion hazard--becomes larger with an increase in the size of the cargo tank.