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MAUI · WATER QUALITY RANKINGS

Calmest Beaches on Maui for Water Quality

Data-driven rankings based on DOH bacteria testing, contamination sources, and ocean flushing patterns.

⚠ Important — Rankings based on historical data, not real-time testing. Always check current advisories and avoid swimming after rain or in brown/murky water.

Top-Ranked Maui Beaches for Clean Water

1
Kapalua Bay
West Maui. Sheltered bay with excellent water clarity. Minimal stream input, well-maintained resort area. Consistently clean results.
Low Risk — 1/5
2
Wailea Beach
South Maui. Dry leeward coast, resort infrastructure, good ocean circulation. Low rainfall reduces runoff risk.
Low Risk — 1/5
3
Ulua Beach
South Maui. Protected cove near Wailea. Good snorkeling conditions, minimal contamination sources.
Low-Moderate Risk — 1.5/5
4
Polo Beach
South Maui. Dry coast, resort area, good flushing. Slightly more enclosed than Wailea but still tests well.
Moderate-Low Risk — 2/5
5
Kaʻanapali Beach
West Maui. Open ocean exposure, resort-maintained. Northern end near Kahana can be affected by stream runoff after rain.
Moderate-Low Risk — 2/5
6
Makena Beach (Big Beach)
South Maui. Remote, undeveloped, excellent ocean exposure. Powerful shorebreak is the main risk, not bacteria.
Moderate-Low Risk — 2/5
7
D.T. Fleming Beach
West Maui. Good ocean flushing but some stream influence. Generally tests well in dry conditions.
Moderate-Low Risk — 2/5
8
Kamaole Beaches (I, II, III)
South Maui, Kīhei. Residential area with cesspool density. Generally acceptable but can spike after rain.
Moderate Risk — 2.5/5
9
Baldwin Beach
North Shore. Stream mouth influence, agricultural runoff. Wetter side of island means more frequent rain impact.
Moderate Risk — 3/5
10
Hoʻokipa Beach
North Shore. Stream influence, agricultural watershed. Popular for windsurfing but water quality can be variable, especially after rain.
Moderate Risk — 3/5
⚠️ The 72-Hour Rain Rule

After heavy rain, avoid swimming at all Maui beaches for at least 72 hours. Maui's agricultural land and cesspool-dense residential areas produce significant runoff that affects even normally clean beaches.

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Understanding Water Quality in Hawaii

Hawaii’s Department of Health monitors approximately 57 beaches statewide through regular bacteria testing. However, with over 300 swimmable beaches across the islands, many popular spots have no regular testing program. Water quality varies significantly based on rainfall, stream proximity, coastal development, and ocean circulation patterns.

After heavy rain, streams and storm drains carry bacteria, sewage, pesticides, and sediment into coastal waters. The DOH recommends staying out of the ocean for at least 48 to 72 hours after heavy rain, even if the water appears clear. Brown or murky water is a visible sign of contamination, but bacteria can be present in clear water near stream mouths.

This site aggregates data from six sources — DOH advisories, USGS stream monitoring (25 stations), NOAA tide and temperature data, NDBC wave buoys, NWS weather alerts, and City & County of Honolulu water testing — to provide a more complete picture than any single source.

72-Hour Rain Rule

The 72-hour rule is the standard guideline from the Hawaii Department of Health: avoid swimming for at least 72 hours after heavy rain stops, especially near stream mouths, canal outlets, and areas with brown or discolored water. This applies to all beaches across all islands.

Bacteria from urban runoff, agricultural land, and aging cesspool systems enters the ocean through streams and storm drains. Hawaii has approximately 88,000 cesspools — more than any other state — many of which leak untreated sewage into groundwater that eventually reaches the coast. Beaches near known cesspool contamination areas carry higher risk, particularly after rainfall.

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⚠️ Important Disclaimer

Safe to Swim Hawaii is an independent passion project. Rankings are estimates based on publicly available data, not real-time measurements.

Always verify conditions with the Hawaii DOH Clean Water Branch.

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. 🤙

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