
Always use one of these types of water:
- Distilled
- Micro-filtered (through 0.2 micron)
- Commercially bottled; freshly opened
- Previously boiled and cooled to lukewarm or body temperature; used promptly
Here are published recommendations from the US FDA and CDC regarding water used for nasal irrigation: FDA Guidance / CDC Guidance.

New User Water Tip
Most users prefer to warm their water prior to use. If you do this, do not overheat the water. It should be lukewarm to the touch and not hotter than about 85°– 90°F (29°– 32°C).
Warning: DO NOT USE TAPWATER UNLESS STERILIZED BY BOILING