One of the most common questions I get from visitors is this: Should I buy bottled water or drink the tap water when I visit Hawaii?
The short answer is: Yes.
According to the Board of Water Supply, Hawaii tap water is some of the best quality drinking water around. It is rainwater that is naturally filtered through underground porous volcanic rock for about 25 years before it reaches aquifers.
“It is very pure and requires very little treatment,” Erwin Kawata, the Honolulu Board of Water Supply’s Water Quality Division program administrator told Civil Beat.
Kawata told the online news source, Civil Beat, “There is almost no bacteria in the water in Hawaii, which is why the chlorine which has to be put into the water here is very low compared to other cities.” Very low means zero to 0.15 milligrams per liter.
In fact, if you buy bottled water on Oahu, it’s very likely the exact same water you would find if you filled your bottle from the sink in your hotel. That’s because bottled water for sale on Oahu comes from the same aquifers as our tap water.
Kawata says that many mainland cities use surface water from rivers and lakes — water that is exposed to contaminants in the air. But, Hawaii’s water, which percolates through basalt below the ground, is protected from airborne bacteria.
The Honolulu Board of Water Supply says Oahu’s municipal water is safe to drink and use, and it does not require treatment by home filtration units.
Yet in spite of all the scientific evidence and the regular testing of all municipal water in Hawaii, there is a subtle effort by some water treatment companies and bottled water manufacturers to make us feel uncomfortable about the water from islands’ taps.
And, to be fair, many visitors to Hawaii live in places where the tap water ISN’T safe. So, it makes sense to feel skeptical.
If you still want to buy bottled water while on vacation in Hawaii, you might see the name brand, Menehune. Menehune is the state’s biggest bottled water company.
Joseph Hartzman, the company’s director of sales and marketing told Civil Beat that Menehune’s bottled water is from the same aquifer as regular tap water but that it has been filtered in an eight-step reverse osmosis process that removes 99 percent of the water’s minerals.
In reverse osmosis, dissolved inorganic solids are removed from water by using pressure to push the water through a semi-permeable membrane. The membrane allows the water to push through but not the dissolved solids, which are flushed down the drain.
Hartzman told Civil Beat that demineralized water “assimilates into our bodies a lot quicker than when minerals are blocking the way.”
But, according to the online news source, there is no scientific proof reverse osmosis makes water assimilation speedier or that demineralized water is healthier.
Kawata of the Honolulu Board of Water Supply told Civil Beat that, even if the science to back up companies’ claims that reverse osmosis water is healthier is non-existent, “if people feel more comfortable drinking it, it’s their choice. It’s a personal matter.”
According to Civil Beat, all water in Hawaii is treated with chlorine and in some areas the water is routinely treated with granular activated carbon.
Each year the Board of Water Supply and the Department of Health conduct thousands of tests on drinking water as required for all states by the U.S. Environmental Protection Department. Kawata says by federal and state law, water cannot be served unless it is safe.
Hawaii’s almost-omnipresent trade winds carry with them moisture that has evaporated from ocean water warmed by the sun. The winds blow across the ocean and reach Oahu from the northeast, then are deflected upwards as they hit the steep cliffs of the Koolau Mountains. The rising moisture cools as it reaches the mountaintops then forms clouds, condenses and falls as rain. If Oahu didn’t have both mountain ranges and flat plains, the island wouldn’t be able to capture the moist air needed to support the living things that exist now. (The island of Niihau, on the other hand, gets very little rainfall because it doesn’t have much in the way of elevated slopes.)
In a year, about two billion gallons of rain fall on Oahu every day. About a third of that replenishes the island’s aquifer (the layer of rock, sand and gravel ground water flows through), another third nurtures the island’s vegetation and the rest runs off into the ocean.
For the drinking water you’ll enjoy while you’re here, the Honolulu Board of Water Supply uses four shafts, 12 tunnels and 84 well stations around the island to draw water from the ground. Dike Tunnels are drilled through a mountain to its dike rock compartment where freshwater is drawn out before it reaches the aquifer. Inclined shafts descend hundreds of feet to the top of the aquifer, skimming its upper layer to extract fresh water. Deep wells are located over the aquifer and supply most of the island’s water.
On the surface, the water enters a complex and unique water transmission system, which transports water from pumping stations to customers. Pumping stations pump water from the shafts, tunnels and wells into the transmission system. Sometimes, booster stations are used to push water over long distances and to higher elevations. The purpose of pumping and booster stations is to deliver fresh water to the reservoirs, which store water for future use. Finally, when water is needed, it’s fed back into water mains for delivery to hotels and resorts, homes and businesses. More than 2,000 miles of transmission mains are utilized to convey fresh water from the pumping stations to the reservoirs, and to your hotel room and the restaurants you visit.
Drink up. It’s good stuff.
Bottom line? Hawaii tap water IS safe to drink. And, it’s no less-safe than bottled water, most of which comes from the same place as our tap water. So, drink up and feel good about it!