My dad has high blood pressure and high cholesterol and recently, his doctor wanted to put him on medications for these, but wanted to give him 3 months to try it naturally. I'm taking on the duty of finding more natural cures than the drugs.
I'm no expert, but from what I've read it is the retention of water that salt causes which can be one reason that blood pressure increases. I suppose that consuming more water in the absence of salt may help to flush excess salt from the system. Sounds plausible.
I have read that diuretics or water pills which help to remove water from the system can help to reduce BP temporarily. However, I don't believe this is a recommended means of keeping BP low. Most of the time, the recommendation is low salt, D.A.S.H. diet, and exercise if you're going to try to combat it without yet seeking a doctor's help or medications.
One other thing that I stumbled onto recently on the health boards was related to breathing exercises that help to lower BP. Taking long, slow and deep breaths seems to bring it down quite a bit in some cases. Check out the thread on "please join me in an experiment...." It may depend though on whether you are dealing with both high systolic and diastolic pressure or just high systolic.
I've heard of eating celery lowering BP but you'd have to eat it at least once a day and a fair bit of it. It'd also have to be a ongoing thing. If you check your library or on the net it shows studies that have been done with lowering HBP and how long the study was for etc. It may help.
Goodluck with it and good on you for helping your Dad
Sweating can drop BP a lot. I use a steam room and sauna regularly for just that purpose...and of course it FEELS good. Too bad as we age, sweating seems to be less and less common...or else maybe there's more air-conditioning than there used to be?
I've never believed the dieter's old saw that overdrinking water was good for losing salt. It may be a slight diuretic, or not, but I've never experienced anything but a RAISED BP when I force water, so I don't anymore.