Water quality considerations for pregnant visitors — lowest-risk beaches, when to avoid the ocean, and freshwater leptospirosis dangers.
This guide is for general informational purposes only. Consult your OB/GYN or healthcare provider about ocean swimming during your specific pregnancy. Every pregnancy is different.
Pregnancy involves natural changes to the immune system. The body partially suppresses immune function to prevent rejection of the developing fetus. This immunomodulation means that bacterial infections from contaminated water may be more likely to take hold, symptoms may be more severe, and recovery may take longer compared to a non-pregnant person with the same exposure.
Dehydration from gastrointestinal illness (the most common result of swimming in contaminated water) is particularly concerning during pregnancy. Even mild dehydration can affect amniotic fluid levels and potentially lead to premature contractions. This alone is reason to be more cautious about water quality when pregnant.
Certain infections that might be mild in healthy adults can have more serious implications during pregnancy. Leptospirosis, which is acquired from freshwater in Hawaiʻi, has been associated with adverse pregnancy outcomes. Vibrio infections, while rare, are also more dangerous for immunocompromised individuals.
The lowest-risk beaches share several characteristics: they are located on dry, leeward coastlines with minimal stream input, have no cesspools in their immediate watershed, receive few or no brown water advisories, and have consistently low Enterococcus counts in DOH testing.
Always check current advisory status before visiting. Conditions change with weather.
Leptospirosis is a bacterial infection acquired from contaminated freshwater — streams, waterfalls, and ponds. Hawaiʻi accounts for approximately 50% of all U.S. cases. The bacteria come from the urine of infected animals (rats, mongooses, pigs, cattle) that washes into waterways.
During pregnancy, leptospirosis is particularly dangerous. The infection can cause high fever, organ damage, and has been associated with adverse pregnancy outcomes. There is no vaccine available for humans.
Ocean water does not carry leptospirosis risk. This is specifically a freshwater concern.
If water quality conditions are not ideal or you want to avoid the risk entirely, most Hawaiʻi resorts and hotels have well-maintained swimming pools. Chlorinated pool water poses minimal bacterial risk compared to ocean water. Many hotels on the beach offer poolside ocean views — you can enjoy the scenery without the contamination risk.
Prefer to stay dry? Top-rated land-based activities perfect for pregnant travelers.
Tours listed via Viator and GetYourGuide. Safe to Swim Hawaii may earn a commission if you book, at no extra cost to you.
Free alerts when water quality changes at your beach.
No spam. Just safety alerts for your trip.
Safe to Swim Hawaii aggregates water quality data from six independent sources to provide broader coverage than any single agency. Our sources include the Hawaii Department of Health Clean Water Branch (beach advisories and bacteria testing), USGS National Water Information System (25 stream monitoring stations across all islands), NOAA CO-OPS (tide levels and water temperature), NDBC (wave buoys and ocean conditions), NWS Honolulu (weather and marine alerts), and City & County of Honolulu Environmental Services (Kailua Bay water testing and spill reports).
Historical bacteria risk ratings on this site are based on DOH testing data, Surfrider Foundation monitoring, geographic analysis (stream proximity, cesspool contamination areas, coastal development), and advisory frequency. These are historical assessments, not live measurements. Always check the live advisory status at the top of each page and verify conditions with the Hawaii DOH Clean Water Branch before entering the water.
⚠️
Safe to Swim Hawaii is an independent passion project — not affiliated with the Hawaii Department of Health. This page provides general health information and is not medical advice. Consult your OB/GYN about ocean swimming during pregnancy.
Always verify current water quality with the Hawaii DOH Clean Water Branch before entering the water.
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. 🤙
Less rainfall means less runoff and generally cleaner ocean water across all islands. Stream flows drop, reducing bacteria transport to coastal areas. This is typically the best time for ocean water quality, though localized contamination from cesspools and urban runoff can still occur.
Frequent heavy rain events cause stream flooding, sewage overflows, and brown water advisories. Windward and north-facing coasts receive more rain. The DOH issues the most advisories during this period. Leeward coasts (west-facing) generally stay drier and cleaner year-round.
Water quality patterns vary significantly by location. Beaches near stream mouths and urban areas show the most dramatic seasonal variation. Open ocean beaches with strong wave action maintain better water quality year-round. Check individual beach pages for location-specific seasonal data.
Hawaii has approximately 88,000 cesspools — more than any other U.S. state. These underground chambers collect untreated household sewage and allow it to leach into the surrounding soil and groundwater. In coastal areas, this contaminated groundwater eventually reaches the ocean through submarine groundwater discharge, contributing to elevated bacteria levels at nearby beaches.
Hawaii Act 125 (2017) requires all cesspools to be upgraded or converted to approved septic systems by 2050. Priority areas near the coast and drinking water sources are being addressed first, but progress has been slow. Beaches in known cesspool contamination zones carry elevated bacteria risk even during dry weather. For more information, see our comprehensive cesspool guide.