This volume of water can later be topped up with water from any source, but if there were less than 40 seahs of water in the mikveh, then the addition of 3 or more pints of water that was at any time intentionally collected in any vessel or transferred by a human, would render the mikveh unfit for use, regardless of whether water from a natural source was then added to make up 40 seahs from a natural source; a mikveh rendered unfit for use in this way would need to be completely drained away and refilled from scratch in the prescribed way.