Mastering Water Catchment

In Hawaii, where the lush landscapes meet modern living, an estimated 30,000 to 60,000 individuals lean on rainwater catchment systems as their primary water source ^[1]. This reliance underscores not just a way of life but a critical infrastructure for drinking water, bathing, and gardening purposes.

Unlike on the mainland, these systems in Hawaii are unregulated by the Department of Health, putting the onus on homeowners to ensure their water supply is safe and reliable ^[2]. It’s essential, then, to follow the “Guidelines on Rainwater Catchment System for Hawaii” for proper installation and upkeep, ensuring the integrity of your water supply with regular maintenance and DOH-recommended testing ^[2].

Navigating the waters of rainwater harvesting in Hawaii can be as much about embracing island living as it is about understanding and managing your water catchment area effectively. Homebuyers and renters are advised to delve into the particularities of living with a rainwater catchment system, considering its maintenance needs and the soft, mineral-free water it provides, which is kinder on plumbing and appliances ^[4] ^[3]. This introductory guide aims to shed light on setting up, maintaining, and troubleshooting your water catchment and harvesting systems, offering a comprehensive overview to ensure you’re well-prepared to harness Hawaii’s bountiful rainwater for your household needs ^[2].

Understanding Rainwater Catchment Systems

Rainwater catchment systems, a staple for many Hawaiian homes, especially on the Big Island, offer a sustainable solution to water supply challenges. These systems collect rainwater from rooftops, typically made of metal, and channel it into storage tanks through gutters ^[8]. The tanks are usually lined to ensure the water remains clean and safe for use ^[8]. This method not only provides a reliable source of water but also contributes significantly to water conservation efforts, making it an economically wise choice for homeowners ^[7].

Key Components and Maintenance of Rainwater Catchment Systems

Collection Surfaces: Ideal materials for roofs include coated metal, slate, or Tesla’s Solar Roof Tiles, which are effective in capturing rainwater ^[6].

Storage Options: Various tanks can be used, such as corrugated steel, concrete, or polyethylene tanks, each offering different benefits and suitability depending on the location and budget ^[10].

Maintenance Practices: Regular checks and cleaning of gutters, screens, and first-flush diverters are crucial to prevent blockages and contamination. It is also important to inspect the tank liner periodically for any signs of wear or damage ^[10].

By integrating these systems into their homes, residents can significantly reduce their reliance on potable water for non-drinking purposes, which is particularly beneficial given that up to 50% of water usage can occur outdoors ^[9]. Furthermore, these systems are not only practical but also add a layer of security as a backup water source during emergencies or natural disasters ^[7].

Setting Up Your Catchment Tank

When setting up your catchment tank in Hawaii, there are several key considerations to ensure the system is efficient, safe, and durable:

Material Choices

1. Polyethylene Tanks

Pros: Polyethylene tanks are lightweight, making them easier to transport and install. They are resistant to corrosion and chemical attacks, which is essential in the acidic rain conditions prevalent in some parts of Puna. These tanks are also less expensive compared to their metal or concrete counterparts.
Cons: They can be less durable than concrete or metal tanks and may not withstand the test of time as well, especially in areas with high UV exposure.

2. Fiberglass Tanks

Pros: Fiberglass tanks are known for their durability and resistance to corrosion. They can handle a wide range of chemicals and are suitable for underground installations, such as septic systems.
Cons: The initial cost of fiberglass tanks can be higher than polyethylene tanks. Installation requires careful handling to avoid cracks.

3. Concrete Tanks

Pros: Concrete tanks are incredibly durable and can last for decades if properly maintained. They are well-suited for below-ground installations and can withstand the weight of the soil above them.
Cons: The weight of concrete tanks makes installation more challenging and expensive. They are also prone to cracking if not properly constructed or if the ground shifts.

4. Stainless Steel Tanks

Pros: Stainless steel tanks offer excellent durability and resistance to corrosion. They are suitable for storing potable water and can withstand the harsh environmental conditions of the Puna District.
Cons: Stainless steel tanks are among the most expensive options. They also require regular maintenance to prevent corrosion in the long term.

Installation Considerations

Location

Choose a location that is easily accessible for maintenance and sufficiently elevated to prevent flooding during heavy rains, common in the Puna District.

Foundation

Ensure a solid foundation for the tank, especially for heavy concrete and stainless steel tanks. A stable base prevents shifting and potential damage.

Professional Installation

Given the complexity of tank installations and the specific challenges of the Puna District’s environment, hiring professionals with local experience is advisable. They can ensure the tank is installed correctly and complies with all local regulations.

Catchment Tank Costs

Embarking on tank installation in Hawaii’s Puna District necessitates a deep understanding of its distinct environmental and geological characteristics. This region, characterized by its volcanic landscape, tropical climate, and high precipitation levels, demands careful selection of materials and methods for tank installations for water storage or septic purposes.

Tank Installation and Material Choices

Galvanized Steel Tanks:
- Cost: Approximately $5,000 for a 10,000-gallon tank with liner.
- Location: Puna area.
Polyethylene Tanks:
- Note: Prices may be higher per gallon due to smaller capacities.
- Capacity: Up to 4,000 gallons, potentially insufficient for larger needs.

Installation Costs

General Overview:
- Costs vary with system complexity, tank size, and project nature (DIY vs. professional).
- Professional Installation: May include site preparation, downspout connection, and pump and pipe setup.
Labor Costs:
- Landscapers: $50 to $100 per hour.
- Wet System Installation: Extra costs of $440 to $760 for about 3 hours of work due to excavation needs.

Additional Components

Irrigation and Sprinkler Systems:
- Cost Range: $4,000 to $7,000.
Water Treatment Systems:
- General Cost: $2,500 to $3,000.

Installation Resources:

WaterWorks Hawaii
1717 Kamehameha Ave Ste A Hilo, 96720
808-933-9111 
https://www.waterworkshawaii.com/

ISLAND CATCHMENT CO.
15-1934 33rd Ave, Keaau 96749
808-982-8282
https://islandcatchment.com/

DIY Considerations

System Complexity:
- Simple systems might be DIY-friendly, whereas larger systems may require professional assistance.
Essential Components:
- Gutters, pipes, check valves, filters, and pumps.
- Costs: Approximately $800 for gutters; $800 for pumps and filters (UV filter excluded).
Water Flow and Filtration

o Installation of a First-Flush Diverter: To remove initial contaminants.

o Downspout Positioning: Ensure a continuous downward slope for efficient water flow.

o Inclusion of Screens: To keep leaves and debris out.

o Filtration Process: Begin with a sediment filter, followed by additional filters and UV sterilization.

o Regular Maintenance: Clean and inspect gutters, filters, and tank surfaces to prevent issues.

Maintenance Best Practices

Regular maintenance is crucial for the longevity and efficacy of your rainwater catchment system. Here are some best practices to ensure your system remains in top condition:

Regular Cleaning and Inspection:
- Clean the system’s roof, tank, gutters, and filters periodically to minimize water contamination ^[2].
- Inspect and clean the roof, gutters, downspouts, pre-tank filters, First Flush Diverters, and the storage tank regularly ^[14].
- Ensure that the tank overflow device is functional and that runoff is directed away from the tank to prevent contamination ^[13].

Water Testing and Treatment:
- Test the water for E. coli, turbidity, lead, and copper using a DOH-approved laboratory to ensure it meets safety standards. Acceptable levels are: Turbidity ≤ 5 NTU, E. coli = Absence, Lead ≤ 0.015 mg/L, and Copper ≤ 1.3 mg/L ^[2].
- Install NSF, UL, or WQA certified filtration systems to remove harmful contaminants ^[2].
- Use chlorine treatment at recommended levels of 1 ppm during rainy periods and 4 ppm during dry periods to maintain water safety ^[14].

Preventive Measures and System Enhancements:
- Trim nearby trees to prevent animals from accessing the roof and potentially contaminating the water supply ^[11].
- Regularly check and adjust the pH levels of the water to prevent corrosion and scaling in the plumbing system ^[14].
- Implement additional precautions during increased volcanic activity to protect the water quality ^[2].

By adhering to these maintenance protocols, homeowners can significantly enhance the safety and reliability of their rainwater catchment systems, ensuring a sustainable and efficient water supply.

Water Quality and Treatment Options

Ensuring the safety and quality of rainwater in your catchment system involves several critical steps and considerations:

Regular Testing and Monitoring:
- Homeowners should perform regular screening tests for E. coli, turbidity, lead, and copper. These tests should be conducted using laboratories certified by the Department of Health (DOH) ^[2].
- The acceptable levels for these tests are defined by the EPA: Turbidity should be ≤ 5 NTU, E. coli should show absence, Lead ≤ 0.015 mg/L, and Copper ≤ 1.3 mg/L ^[2].

Filtration and Treatment Systems:
- Installing certified filtration systems is recommended to remove contaminants such as heavy metals and bacteria. These systems should be certified by NSF, UL, or WQA for specific contaminant removal ^[2].
- Common filtration options include charcoal or carbon filters for heavy metals like lead and copper ^[16].
- For adjusting pH levels to prevent corrosion, adding baking soda or calcium carbonate to the water is effective ^[16].

Maintenance and Upkeep:
- Regular maintenance should include checking the structural integrity of tanks and the functionality of filtration systems.
- Disinfection can be achieved by adding regular, unscented bleach to maintain a residual chlorine level of at least 1.0 ppm, especially during rainy periods ^[11].
- It’s crucial to ensure that design and construction of the catchment system use appropriate materials to reduce chemical contamination and protect against disease-carrying animals ^[2].

By adhering to these guidelines, homeowners can significantly enhance the safety and reliability of their rainwater catchment systems, ensuring a sustainable and efficient water supply.

Common Challenges and Solutions

Rainwater catchment systems in Hawaii face unique challenges during periods of increased volcanic activity. Here are some essential precautions homeowners should consider to protect their water supply:

Disconnect and Protect:
- During volcanic eruptions, disconnect the gutters feeding into your catchment tank to prevent ash and other contaminants from entering the water supply ^[15].
- Do not reconnect the gutters until all volcanic hazards have passed and the roof, gutters, and tank surfaces have been thoroughly cleaned to remove any debris ^[15].

Alternative Water Sources:
- Utilize emergency water resources provided by the County of Hawaii Department of Water Supply. They offer emergency spigots which can be a reliable alternative for clean water during periods when catchment systems might be compromised by volcanic ash or debris ^[15].

Comprehensive Precautionary Measures:
- Homeowners should be vigilant and take additional precautions during increased volcanic activity to ensure the safety and functionality of their rainwater catchment systems ^[2] ^[15].
- Regular monitoring and maintenance are crucial, especially in adjusting practices promptly in response to environmental changes brought about by volcanic activity ^[2].

By implementing these strategies, homeowners can mitigate the risks associated with volcanic activity and maintain a safe and reliable water catchment system.

Legal and Environmental Considerations

In Hawaii, the approach to rainwater catchment systems is supportive and minimally regulated, making it an attractive option for homeowners looking to harness natural water resources. Here are some key legal and environmental considerations to keep in mind:

Regulatory Landscape:
- Rainwater harvesting is not illegal and faces no heavy regulations in Hawaii ^[18].
- No permit is required for rainwater catchment systems used for non-potable purposes if the storage capacity does not exceed 360 gallons ^[18].
- The Hawaii County Plumbing Code specifies that systems designed for outdoor drip and subsurface irrigation up to 360 gallons do not require a permit ^[19].

Incentives and Support:
- The Honolulu Board of Water Supply promotes rainwater harvesting by offering incentives for rain barrel installation, encouraging residents to adopt these eco-friendly systems ^[9].
- Senate Concurrent Resolution 172 (2008) encouraged county water boards to explore and promote water conservation via rainwater collection ^[19].

Safety and Best Practices:
- While the Department of Health does not regulate domestic rainwater systems, they recommend homeowners follow the “Guidelines on Rainwater Catchment System for Hawaii” by the University of Hawaii College of Tropical Agriculture and Human Resources to ensure water safety ^[2].
- Homeowners can participate in a program to test their rainwater for lead and copper, helping to maintain safe and healthy water standards ^[2].

These considerations highlight the state’s commitment to supporting sustainable water use practices while ensuring public health and safety.

Conclusion

As your local real estate professional deeply rooted in the beautiful landscapes of the Big Island, it’s been my privilege to guide you through the nuances of rainwater catchment systems, an essential component of living here. Embracing these systems not only showcases our commitment to sustainable living but also ensures we have reliable and safe water sources for our daily needs. The journey we’ve embarked on together in this guide, from installation to maintenance and understanding legal considerations, reflects the unique lifestyle that Hawaii offers, integrating modern living with respect for natural resources.

In conclusion, mastering the art of water catchment is more than just a practical necessity; it’s a testament to the resilient and eco-conscious spirit of our community. As you move forward, remember the importance of regular upkeep and staying informed about the latest in system maintenance and water quality to ensure your home remains a sanctuary of health and sustainability. Whether you’re setting up a new system or optimizing an existing one, my hope is that this guide serves as a valuable resource in your journey to efficient and responsible water use on the Big Island. Together, let’s uphold the beauty and sustainability of our island home for generations to come.

FAQs

1. Are water catchment systems legal in Hawaii?

When installed on individual homes, water catchment systems are not regulated by the Hawaii Department of Health (DOH). However, the DOH does encourage homeowners to implement proper safety measures to ensure the water collected is safe for use.

2. What is the cost of a water catchment system in Hawaii?

In Hawaii, the annual operating cost for a fully-equipped rainwater catchment system is approximately $370, or about $30.83 per month, for a typical home.

3. What are the maintenance requirements for a water catchment system?

To maintain a water catchment system effectively:

Inspect and clean your gutters and downspouts monthly to remove any debris, which can affect water quality.
Conduct a thorough cleaning of gutters and downspouts several times a year, particularly after windy storms.
Regularly clean and check the pre-tank filter and First Flush Diverter every month to ensure optimal operation.