Irrigating the nose with saline once or twice daily offers a number of benefits, particularly for those who experience chronic rhinitis or sinusitis on an allergic or other basis. Flushing the nose out with salt water (of balanced salinity, mimicking the concentration of body fluid) removes debris, accumulated and dried secretions, pollen grains and other allergens, and reactive cells and the histamine they secrete.
The result is a reduction of symptoms and prevention of infection, among other benefits claimed by those who employ this measure as part of their daily hygiene.
The irrigations are done over the bathroom sink (lavatory) using a three-ounce
infant enema syringe or other high capacity 
rubber
syringe, and "normal" saline solution, either purchased or made by adding
one-fourth to one-half teaspoon of salt to a cup of water. Simply
stand at the sink, leaning over it, and flush each side of the nose several
times with the salt solution. Then blow your nose or gently twist tissue
in each nostril to remove the excess solution and any remaining debris.
Your cup, syringe, and other supplies and utensils must be kept scupulously clean.
The concentration of the salt solution is made so as to be the same concentration as tears or other body fluid so that it is soothing to the delicate membranes of the interior nose. If plain water were used, it would sting and possibly even aggravate the symptoms of congestion you are trying to treat. A stronger solution of salt likewise would sting, and offers no benefit.
Following the irrigation is the ideal time to administer decongestant or steroid nasal sprays.
Copyright 1995, Wm. P. Alford, M.D.