Do you know your water?
Only 3% of earth's water is fresh water. The other 97% is salt water. You can find this fresh water in glaciers, ice caps, icebergs, lakes, ponds, underground aquifers and streams, etc. Fresh water has less than .05% salinity. It is also the least dense out of all types due to this lack of salinity.
Brackish water, also known as Briny water, is the result of the water having more salinity in it than fresh water. However, it doesn't have as much salt in it as sea water. Brackish water can come about by mixing sea water and fresh water. Brackish water has about .05-3% salinity making it the middle most dense water.
Salt water is the most dense out of brackish water and fresh water. The salinity in salt water is higher than the other two types as well. The percentage of salt in seawater is usually around 3.1 to 3.8. Often times this seawater mixes with fresh water, so of course this percentage is not uniform for all areas. The density of seawater is about 1020 to 1029 kg/m3.