No, the primary way to dig for seasalt water is to evaporate the water.The remaining water will have a continuously higher salt ratio, until the water is completely saturated, and salt cristals will...
What you have to do is leave the water and salt out overnight so that the water evaporates leaving the salt behind . This might be true for a very small amount of salt water, but for any larger...
They will both evaporate but the water with salt in it will leave the salt behind and it will once again become clean water. It will also leave other impurities out.