Which beaches recover first and which to avoid after storms
The Hawaii Department of Health recommends staying out of the ocean for at least 72 hours after heavy rain. Rain washes bacteria, fertilizers, and other pollutants from land into the ocean through streams, storm drains, and direct runoff. Some beaches recover faster than others depending on drainage, currents, and proximity to runoff sources.
On Oʻahu, these beaches typically have better water quality sooner after rain: Ko Olina Lagoons, Waikiki (eastern end), Lanikai Beach, Yokohama Bay. These locations are either on dry leeward coasts, far from stream outlets, or have strong ocean currents that flush contamination quickly.
These Oʻahu beaches are more affected by runoff and take longer to recover: Ala Moana Beach (Ala Wai Canal), Kahana Bay, Bellows Beach, Sandy Beach after flooding. Beaches near stream mouths, canals, or in areas that receive heavy rainfall are most impacted.
The Ala Wai Canal is the single biggest factor in Oʻahu water quality after rain. It collects runoff from the entire Honolulu watershed and dumps it into the ocean at the west end of Waikiki. Beaches near the Ala Wai outfall (Duke Kahanamoku Beach, Ala Moana) take longest to recover. North Shore beaches can be affected by agricultural runoff from the central plain.
Use the live advisory check on each beach page to see if any DOH advisories are currently posted. If it rained recently and no advisory is posted, that does not necessarily mean the water is clear — not every beach is tested after every storm. Look for brown, murky, or discolored water as a visual indicator. When in doubt, wait.
Free alerts when water quality changes at your beach — brown water advisories, bacteria warnings, and all-clear notices.
No spam. Just safety alerts for your trip.
500+ beaches and 25+ hotels across all 6 islands
Safe to Swim Hawaii provides water quality information based on publicly available DOH data and seasonal patterns. This is not medical or safety advice. Always check current conditions, obey posted signs, and use your own judgment before entering the ocean. Privacy Policy
⚠️ Important Disclaimer
Safe to Swim Hawaii is an independent passion project — not affiliated with the Hawaii Department of Health or any government agency. Water quality ratings are estimates based on publicly available testing data and geographic analysis. They are not real-time measurements and may not reflect current conditions.
Always verify current water quality conditions with the Hawaii DOH Clean Water Branch before entering the water.
When in doubt, don't go out. 🤙