How does Waimanalo Beach compare to Kailua Beach for water quality?

Both Waimanalo and Kailua Beach have similar moderate-low bacteria risk ratings. Kailua Beach has slightly more urban runoff potential from Kailua town, while Waimanalo has agricultural runoff risk. Both are Windward beaches with good ocean circulation. After rain, both can be affected by runoff, so the 72-hour rain rule applies to both.

What is the water quality like at Waimanalo Beach?

Waimanalo Beach generally has good water quality thanks to its long open shoreline and strong ocean circulation. The main water quality concern is stream runoff from agricultural areas after heavy rain, which can temporarily elevate bacteria levels. During dry weather, the beach typically tests well.

When is the best time to visit Waimanalo Beach?

For water quality, visit during dry weather periods and avoid swimming for at least 72 hours after heavy rain. Waimanalo Beach is beautiful year-round but the Windward side gets more rain than the leeward coast. Summer months are generally drier. Early mornings are less crowded and conditions are often calmest.

Is Waimanalo Beach better than Lanikai Beach?

Waimanalo Beach is much longer and less crowded than Lanikai, with a wider sandy beach. Lanikai has calmer, more sheltered water ideal for swimming and kayaking. For water quality, both are similar. Waimanalo offers more space, while Lanikai offers the iconic Mokulua Islands view. Both are excellent Windward Oahu beaches.

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OAHU · WINDWARD

Waimanalo Beach

Q: Can you swim at Waimanalo Beach today?

Check the live DOH advisory module on this page first. Waimanalo Beach has strong open-ocean circulation along the main shoreline, but Waimanalo Stream can carry bacteria after rain. The latest Surfrider Blue Water Task Force sample for Waimanalo Stream was 860 MPN/100mL on April 19, 2026, above the 130 MPN/100mL Beach Action Value. Avoid brown or murky water and give stream mouths extra distance after rain.

Water quality status and bacteria risk rating

📍 Windward Oʻahu, about 30 min from Waikiki

Can you swim at Waimanalo Beach today?

Start with the live DOH status below. The main beach has strong open-ocean circulation, but Waimanalo Stream is the key bacteria watchpoint after rain. The latest Surfrider Blue Water Task Force sample at Waimanalo Stream was 860 MPN/100mL on Apr 19, above the 130 MPN/100mL Beach Action Value.

Quick read · Waimanalo water quality

• Main beach: long, open shoreline with good circulation in dry weather.

• Stream mouth: give Waimanalo Stream extra distance after rain or when water looks brown.

• Latest community test: 860 MPN/100mL at Waimanalo Stream on Apr 19, 2026.

• Threshold: 130 MPN/100mL enterococcus. Above that, the sample exceeds the Beach Action Value.

Checking live advisories…

Community Water Testing

The Hawai‘i Department of Health does not run routine bacteria-testing here. The readings below come from the Surfrider Foundation’s volunteer Blue Water Task Force, which fills coverage gaps DOH doesn’t reach.

Community Testing · Surfrider BWTF

Waimanalo Stream

Last sample 2026-05-03 · view full report →

1019 MPN/100mL

exceeds BAV

About: Volunteer water-quality monitoring by the Surfrider Foundation's Blue Water Task Force. Method: IDEXX Enterolert (MPN/100mL). Threshold: 130 MPN/100mL Beach Action Value — matches Hawaii DOH. Sampling: monthly (Kauaʻi/Maui), biweekly (Oʻahu).

Source: Surfrider Foundation Blue Water Task Force · Updated 2026-05-15

⚠

If It Looks Brown, Don't Swim

Never enter the ocean when the water appears brown or murky, even if no advisory is posted. Hawaii is often slow to test beaches and update advisories — not every beach is monitored. After heavy rain, wait at least 72 hours and until the water clears before swimming.

Learn more about brown water advisories →

Historical Bacteria Risk

⚠ Historical rating — this is based on long-term testing data, not current conditions. The state of Hawaii is often slow to test beaches and update advisories. Always check the water yourself and avoid brown or murky water.

Moderate-Low Risk 2 / 5

Waimanalo Beach has historically baseline shoreline water quality. This long stretch of open beach on Oʻahu's Windward coast has strong ocean circulation, especially away from the stream mouth. Voted #1 beach in America multiple times, it is one of the most beautiful beaches in Hawaiʻi.

Waimanalo Stream is the main bacteria watchpoint. The latest Surfrider Blue Water Task Force sample measured 860 MPN/100mL at Waimanalo Stream on Apr 19, 2026, above the 130 MPN/100mL Beach Action Value. During dry weather the main beach can be very different from the stream mouth. After rain, follow the 72-hour rule, give stream mouths extra distance, and check the water visually before swimming.

Based on: DOH beach monitoring, open ocean exposure, agricultural stream runoff potential

⚠️ The 72-Hour Rain Rule

The Department of Health recommends staying out of the ocean for at least 72 hours after heavy rain. Waimanalo Beach is on the Windward side which gets more rainfall than leeward areas. Agricultural runoff from nearby land can temporarily elevate bacteria levels after storms. Wait for dry weather and clear water before swimming.

Waimanalo Beach Area — Nearby Accommodations

🏨 Residential Area

No major hotels — closest are in Kailua (15 min) or Waikiki (30 min)

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⚠️ Important Disclaimer

Safe to Swim Hawaii is an independent passion project — it is not affiliated with the Hawaii Department of Health or any government agency. Water quality ratings on this site are estimates based on publicly available testing data and geographic analysis. They are not real-time measurements and may not reflect current conditions. “No DOH Alerts” means no advisory is currently posted — it does not mean the water was tested and found safe. DOH only monitors a fraction of Hawaii’s beaches, and some areas have no regular testing at all.

Always verify current water quality conditions with the Hawaii Department of Health Clean Water Branch before entering the water. This site is for informational purposes only and should not be the sole basis for any swimming decisions.

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This site does not recommend or advise anyone to swim at any beach. We share government data and geographic analysis so you can make your own informed decisions. By using this site you accept full responsibility for your own safety. See our Terms of Use for full details.

When in doubt, don't go out. 🤙