text: is there a way to make water weigh less?   it depends what you mean by weigh less.  * if you are referring to its density, cooling it below 0°c at standard temperature and pressure will freeze it, and reduce its density (boiling it above 100 c again will have the same effect).  * if you are just referreing to the weigh (and not the mass), taking your water to a place with a lower gravitational field than earth's field (eg the moon, or in a space station in orbit) will make it "weigh less"; since p = m g. where p is the weigh vector and g is the gravitational field.  beware: heating it to water vapour (or freezing it to ice) will not reduce its weight, just its density.