I am trying nasal rinses, but so far haven't had any luck with allergy symptoms using only saline. It does get rid of extra mucus but only temporarily. However, my allergist recommends it, along with other treatments.
I like the larger bottle types, like Neil Med. Don't use tap water, as there was a recent report by the CDC about brain-eating ameba from a netti pot using contaminated household tap water. Boiling will kill it. http://www.cdc.gov/parasites/naegleria/infection-sources.html I use distilled water heated 30 sec in the microwave. Salt 1/2 tsp and a pinch of baking soda, or use the 2300 mg/700 mg packets for 750 ml water.
Water from hot water heaters can be dangerous if they are set below 145 degrees. It's nice to have water set low to save energy and not scald kids, but if it's too low it can encourage all sorts of pathogens. Water from the tap should be let run if it hasn't been used in the last 6 hours to wash out lead from brass plumbing fittings.