I know you said you have increased your water intake, but have you tried drinking 6-8 ounces BEFORE your SWF? I know it sounds awful to take in even more liquid at that point in time, but it sort of fills your cells so they do not absorb the salt.
I drink 6-8 ounces before, sometimes a little during, and definitely at least 6-8 immediately after consuming the SWF. It has helped me with this issue.