The water that is “dropped” from an evaporative at regular intervals or after the system is turned off, will generally contain a higher level of salts.
This is because the water is evaporated through the operation of the unit, creating the cool air. The water that is left in the base of the system will have the salts.
Some plants and lawns will be effected by this salty water, so you should check with your local garden centre.
Some evaporative owners, discharge the water into a water tank, mix in fresh water to break down the salt levels and then discharge this onto their gardens..