Sustainable Water

Because of the limited production and questionable reliability of traditional wells, Kauaʻi's sources of potable water dramatically diminished. Back in the late 1990s and early 2000s, Grove Farm began to develop plans, in conjunction with the Kaua‘i Department of Water, to develop the state’s first surface treatment plant. Opened in late 2005, the Waiahi Surface Water Treatment Plant is the island’s most important source of potable water. To date, Grove Farm has invested over $11 million of capital, and the annual operating expenses to run this facility is approximately $1.6 million. The plant currently produces an average of 2.4 million gallons of water daily. The terms of this facility were reviewed and approved by the Board of the Kaua‘i Department of Water in 2004.

Today, 20% of the island’s residents obtain their drinking water from Waiahi. This facility benefits residents in the Hanamaʻulu – Lihuʻe – Puhi – Wailua, and Kapa‘a areas and the businesses and visitor establishments located there.

After the water is processed, extensive testing for water quality is conducted, and the drinking water exceeds all water quality standards parameters. Interestingly, because of Kaua‘i’s geological age – being the oldest of the main Hawaiian Islands -- we have a naturally high level of bauxite in our soils. Bauxite is a source of aluminum, and in the mid-1900s, several businessmen looked into the feasibility of creating an aluminum processing business.

Water was also provided to the Wailua lands owned by the Department of Hawaiian Home Lands and is available when water flows through the plantation irrigation systems.

Grove Farm contracts Aqua Engineers to operate and maintain the facility. The facility operates under stringent guidelines of the Safe Drinking Water Act, the principal federal law in the United States, to ensure safe drinking water for the public. The State of Hawai‘i Department of Health, Safe Drinking Water Branch, administers the federal law, and regulates the Waiahi SWTP.

Here’s more facts about this important facility and the drinking water that it produces:

Is our drinking water safe?

Yes! Constant testing is conducted and the Waiahi SWTP adheres to strict guidelines of the Department of Health – Safe Drinking Water Branch. Drinking water is regulated by the comprehensive set of laws as set forth in the Safe Drinking Water Act. There are many regulations to protect the public that must be adhered to in order to provide safe drinking water for our residents and visitors.

We were told that high levels of aluminum are in our watershed. Is this true?

That is correct. Although our raw water contains high levels of aluminum, the purification process ensures that the drinking water levels are well in compliance with the standards.

Water sources in the Hawaiian Islands are influenced by volcanic soils,some of which are naturally rich in deposits of bauxite, a rock composed mainly of aluminum-bearing minerals. The United States Geological Survey (USGS) has studied the presence of bauxite on Kaua`i and reports that the bauxite has formed by weathering of basalt of the Kōloa Volcanic Series. The raw water is filtered through the ultra-filtration membrane process which removes silt, pathogens, and bacteria. The clean water is further disinfected and delivered to Puhi, Lihu‘e, Hanama‘ulu, Wailua and Kapa‘a.

Is aluminum a contaminant?

No, aluminum is not considered a “Primary” contaminant under the Safe Drinking Water Act. Aluminum is regulated by “Secondary” standards under the Safe Drinking Water Act. Secondary standards are established as guidelines to assist public water systems in managing their drinking water for aesthetic considerations, such as taste, color, and odor.

Is aluminum added to the water purification process?

Aluminum is not added. However, a coagulant, aluminum chloralhydrate (ACH), is added to the raw water prior to the membrane filtration process. The coagulant reacts with the raw water to remove harmful pathogens and bacteria particles through the filtration process. ACH is the standard coagulant for drinking water membrane filtration plants, is required by the Hawai`i Department of Health, and it meets the certification requirement in National Sanitary Foundation Standard 61.

A coagulant must be added to the surface water treatment process when processing the drinking water. It is usually in an aluminum- or iron-based form. We use aluminum chlorohydrate (ACH), since aluminum is the one element that is most abundant in the earth’s crust – it is part of us – just like iron. The FDA recognizes ACH as aluminum-based salts, which are widely used in water purification to remove dissolved organic material.

Is the ACH added for coagulation a cause for concern in my drinking water?

No. In fact, the aluminum-based coagulant that is required to be added to the treatment process is designated NSF Certified. This means that it has been certified by NSF International, formerly the National Sanitation Foundation, to be safe for consumers. NSF International develops public health standards and certification programs to protect the world’s food, water, consumer products and improve global health.

What happens to the ACH, pathogens, silt and bacteria?

The membrane filters allow only clean water to pass though, making the purified drinking water free of contaminants. The coagulated material, including ACH, pathogens, silt and bacteria, collects on the outside of the membranes and is regularly backwashed. The backwash water is then pumped from the plant to a detention basin where the solids settle. After settling, the clarified water is returned to the Kapaia Reservoir. Only about ten percent of the water that is drawn into the facility is returned to the Kapaia Reservoir. This is water from the backwash of the membranes and other operations of the facility.

Is the discharge water harmful to the environment?

No. In the 15 years of operating the facility, we have passed all toxicity testing – all results have been meeting the standards 100% of the time! The discharge is carefully monitored by the State of Hawai‘i Department of Health – Clean Water Branch. The Clean Water Act exists to protect waterways from becoming toxic environments for aquatic life and to protect our environment.

Regular testing is done of the discharge water to ensure that the water is within acceptable levels for specific elements. In times of adverse weather conditions, we do experience spikes in turbidity and more suspended solids. Due to the high levels of naturally occurring aluminum in the raw water, we have implemented practices to prolong settling of the solids.

Can you explain more about the discharge water?

In general, the water that is returned to the reservoir is cleaner than the intake water. With heavy rainfall, the water contains high levels of turbidity. As you know, Kaua‘i is blessed with abundant rainfall and we are constantly susceptible to weather conditions. Therefore, we will be installing larger holding ponds to allow longer settling times prior to returning the water to the Kapaia Reservoir. This capital project is expected to cost $2.6 million, which will be cost shared with the Department of Water, and will be completed by December 2022.

Another standard for the discharge water is Dissolved Aluminum which the standard is set at 260 micrograms per liter. In all testing to date, the actual Dissolved Aluminum levels have always been reported by an independent laboratory as “non-detectable.”

What is a microgram per liter?

One microgram is equivalent to one part per billion. It is equivalent to one second in nearly 32 years or one sheet in a roll of toilet paper stretching from New York to London!

Why was the Waiahi Surface Water Treatment Plant built in the first place?

In the sugar plantation era, Kauaʻi’s abundant supply of water was used to irrigate thousands of acres of sugar cane. Fresh water aquifers benefited as they were recharged at a rate that was sustainable with Kauai’s demand.

As sugar plantations began closing, aquifers were recharged at a much slower rate. It is also believed that over pumping to supply population and tourism increases also contributed to aquifer depletion. And, Kauai’s geology generally has a low percolation rate and is not as conducive to aquifer recharge as the younger Hawaiian Islands.

This resulted in the aquifers no longer being able to keep up with Kauai’s demand and were being depleted. Hence, the Waiahi Surface Water Treatment plant was built in 2005. This state-of-the-art facility processes potable water for Puhi, Līhu‘e, Hanama‘ulu, Wailua and Kapa‘a – major areas of Kaua’i.

Grove Farm has been accused of “selling water” which is a public trust issue. Is this true?

No. The Public Trust Doctrine provides for the protection of water for purposes, including domestic water use of the general public, particularly drinking water.

From a financial standpoint, the agreement between Grove Farm and the Department of Water enables Grove Farm to be reimbursed for expenses required to produce potable water plus a return on two-thirds of the plant investment, which is about $12.9 million as of mid-year 2020. Just to process the raw water into drinking water costs an average of $1.6 million a year. Based on the average demand of 2.4 million gallons per day, the DOW pays $1.6 million, which just covers expenses. At those levels, no return is being made.

Grove Farm is certainly not in the business of “selling water.” Rather, it was a responsibility we accepted to develop this critical water source, storage and transmission to provide homes and commercial and industrial opportunities in the Puhi – Lihuʻe - Hanamaʻulu area. Think about it – what would happen if this vital water purification facility were not around today?

An educational center for our keiki to learn:

The Waiahi SWTP is an educational learning center for our keiki. Students continue to visit the site through the Grove Farm Educational Modules program to learn about the membrane filtration system and to expand their minds on the importance for building a sustainable Kaua‘i. Our keiki learn that this Waiahi SWTP is one of the most critical infrastructure items for all of Kaua‘i.