The quality of our water is a direct link to the quality of our health.
In Hawai‘i, the safety of your rainwater is your responsibility.
There are no government agencies regulating individual catchment systems—making it essential for homeowners and users to fully understand both the benefits and the risks. If you're relying on rainwater for daily use, you must be equipped with the knowledge to manage your system properly and protect the health of your household and guests. Safe water doesn’t happen by accident—it’s the result of informed, proactive stewardship.
There are no government agencies regulating individual catchment systems—making it essential for homeowners and users to fully understand both the benefits and the risks. If you're relying on rainwater for daily use, you must be equipped with the knowledge to manage your system properly and protect the health of your household and guests. Safe water doesn’t happen by accident—it’s the result of informed, proactive stewardship.
A properly designed rainwater harvesting system must be easy to use—and maintained without compromise.
Routine maintenance isn’t optional; it’s essential to ensuring clean, reliable water. Failure to maintain your system can lead to unsafe water, lower storage capacity, bacterial contamination, and serious health risks to users. Every component—from the roof to the faucet—must be part of a clear, consistent maintenance plan. When systems are neglected, water quality suffers. When they’re maintained, water security thrives.
Routine maintenance isn’t optional; it’s essential to ensuring clean, reliable water. Failure to maintain your system can lead to unsafe water, lower storage capacity, bacterial contamination, and serious health risks to users. Every component—from the roof to the faucet—must be part of a clear, consistent maintenance plan. When systems are neglected, water quality suffers. When they’re maintained, water security thrives.
Stored rainwater is vulnerable to serious contamination—biological, chemical, and metallic.
Every category of contaminant poses a direct threat to water quality and human health, reinforcing the need for proper disinfection or purification. Biological hazards are especially dangerous, as they include disease-causing pathogens from animals and pests. Leptospirosis, giardiasis, and cryptosporidiosis stem from organisms found in the digestive and urinary tracts of mammals. Birds, slugs, geckos, and reptiles can introduce harmful agents leading to salmonellosis, campylobacteriosis, and rat lungworm disease. The risks are real—and treating your water is non-negotiable.
Every category of contaminant poses a direct threat to water quality and human health, reinforcing the need for proper disinfection or purification. Biological hazards are especially dangerous, as they include disease-causing pathogens from animals and pests. Leptospirosis, giardiasis, and cryptosporidiosis stem from organisms found in the digestive and urinary tracts of mammals. Birds, slugs, geckos, and reptiles can introduce harmful agents leading to salmonellosis, campylobacteriosis, and rat lungworm disease. The risks are real—and treating your water is non-negotiable.
Heavy metals are a hidden but serious threat to rainwater quality.
These contaminants often enter through roofing materials, plumbing components, or environmental exposure. In Hawai‘i, lead, copper, zinc, and cadmium can leach from nails, flashings, painted surfaces, and galvanized steel. Volcanic emissions and pesticide drift add further risk. Because rainwater is naturally acidic, it accelerates the corrosion and leaching of metals and chemicals from construction materials—potentially introducing toxic elements into your household water. Without proper safeguards, your roof could be contaminating your tap.
These contaminants often enter through roofing materials, plumbing components, or environmental exposure. In Hawai‘i, lead, copper, zinc, and cadmium can leach from nails, flashings, painted surfaces, and galvanized steel. Volcanic emissions and pesticide drift add further risk. Because rainwater is naturally acidic, it accelerates the corrosion and leaching of metals and chemicals from construction materials—potentially introducing toxic elements into your household water. Without proper safeguards, your roof could be contaminating your tap.
Acid rain is a real and recurring threat to rainwater safety in Hawai‘i.
While globally linked to industrial emissions, here on the islands, acid rain is largely driven by volcanic activity—specifically, sulfur dioxide (SO₂) from Kīlauea. When SO₂ combines with atmospheric moisture, it forms dilute sulfuric acid that falls as acid rain, often with a pH below 5.6. According to the University of Hawai‘i’s College of Tropical Agriculture and Human Resources, Kīlauea emits an estimated 350 metric tons of SO₂ daily during quiet periods and up to 1,850 metric tons during eruptions. Acid rain accelerates corrosion and leaching from rooftops, posing significant risks to your water quality if untreated.
While globally linked to industrial emissions, here on the islands, acid rain is largely driven by volcanic activity—specifically, sulfur dioxide (SO₂) from Kīlauea. When SO₂ combines with atmospheric moisture, it forms dilute sulfuric acid that falls as acid rain, often with a pH below 5.6. According to the University of Hawai‘i’s College of Tropical Agriculture and Human Resources, Kīlauea emits an estimated 350 metric tons of SO₂ daily during quiet periods and up to 1,850 metric tons during eruptions. Acid rain accelerates corrosion and leaching from rooftops, posing significant risks to your water quality if untreated.
Acid rain doesn’t just affect your tank—it attacks your plumbing.
Copper pipes are especially vulnerable, and the impact is intensified when transporting hot water. Even before copper reaches unsafe levels, leaching can leave blue-green stains on porcelain and fiberglass sinks and tubs. Iron leaves behind brown stains, while lead—though toxic—is less likely to discolor surfaces, making it harder to detect without testing. Fortunately, the University of Hawai‘i offers subsidized water testing services. For more information and resources, visit www.tiloscleanwater.com/clean-water-partners.html.
Copper pipes are especially vulnerable, and the impact is intensified when transporting hot water. Even before copper reaches unsafe levels, leaching can leave blue-green stains on porcelain and fiberglass sinks and tubs. Iron leaves behind brown stains, while lead—though toxic—is less likely to discolor surfaces, making it harder to detect without testing. Fortunately, the University of Hawai‘i offers subsidized water testing services. For more information and resources, visit www.tiloscleanwater.com/clean-water-partners.html.
Acid rain in catchment systems has no natural buffer—just your roof and tank.
Unlike groundwater, rainwater collected from rooftops doesn’t pass through soil or rock to neutralize its acidity. In Hawai‘i, areas downwind of volcanic emissions—especially Kā‘ū and South Kona—frequently record rainwater pH levels as low as 4. This level of acidity accelerates corrosion, degrades system components, and increases the risk of metal leaching into your water supply. If you’re not testing and treating your water, you’re taking a chance with every drop.
Unlike groundwater, rainwater collected from rooftops doesn’t pass through soil or rock to neutralize its acidity. In Hawai‘i, areas downwind of volcanic emissions—especially Kā‘ū and South Kona—frequently record rainwater pH levels as low as 4. This level of acidity accelerates corrosion, degrades system components, and increases the risk of metal leaching into your water supply. If you’re not testing and treating your water, you’re taking a chance with every drop.
Tanks and Clean Water filter Pack
Poly Tanks Galvanized Steel tanks Whole House Disinfection
Suggested Maintenance Schedule
A Critical Reminder for All Rainwater Harvesters
The following information is not a complete maintenance manual.
It offers essential guidance—practical steps and serious recommendations—to help you protect what matters most: your health.
Clean, pathogen-free water is not a luxury. It’s a necessity.
As a Rainwater Harvester, your relationship with water is personal and powerful. It directly impacts your well-being, your resilience, and your quality of life.
Water sustains all life. Water is life. Clean water is health.
Rainwater Harvesting empowers self-reliance—especially here in Hawai‘i, a remote island chain in the middle of the Pacific Ocean, built on five volcanoes, surrounded by the Ring of Fire.
Out here, every drop counts. Every decision matters. And living with purpose isn’t optional—it’s essential.
The following information is not a complete maintenance manual.
It offers essential guidance—practical steps and serious recommendations—to help you protect what matters most: your health.
Clean, pathogen-free water is not a luxury. It’s a necessity.
As a Rainwater Harvester, your relationship with water is personal and powerful. It directly impacts your well-being, your resilience, and your quality of life.
Water sustains all life. Water is life. Clean water is health.
Rainwater Harvesting empowers self-reliance—especially here in Hawai‘i, a remote island chain in the middle of the Pacific Ocean, built on five volcanoes, surrounded by the Ring of Fire.
Out here, every drop counts. Every decision matters. And living with purpose isn’t optional—it’s essential.
12 Essential Maintenance Steps for Your Rainwater Catchment System
Chlorine Tablets - * DO NOT USE POOL TABS WITH STABILIZER - THE STABILIZER IS CYANURIC ACID.
There are tablets made for portable water. Always look for the NSF rating!
There are tablets made for portable water. Always look for the NSF rating!
Managing pH Is Essential to Protect Your Water and Your Health
Raising the pH of stored rainwater is a critical step in reducing corrosion and metal leaching.
This can be achieved by introducing alkalizing minerals such as baking soda (sodium bicarbonate), granulated calcium carbonate (calcite), or sodium carbonate (soda ash). Among these options, baking soda is most commonly used due to its availability, affordability, and predictable performance. UTCW Acid Rain Mineral Pack is also a good way to balance pH.
Baking soda acts as a safe neutralizer, allowing pH adjustment without the risk of excessive elevation. However, as noted by Patricia Macomber of the University of Hawai‘i College of Tropical Agriculture and Human Resources, determining the correct dosage is not one-size-fits-all. Each catchment system is influenced by variables such as rainfall patterns, tank volume, roof materials, and existing water chemistry.
When adding chlorine and/or baking soda, always dissolve the material in water first. Pour the solution into the tank and stir thoroughly to ensure even distribution throughout the stored water. A pH of 7.0 is considered neutral. The ideal range for household water falls between 6.5 and 8.5, with a strong recommendation to maintain pH above 6.5 to reduce corrosion and metal leaching—particularly in systems with metal roofing, pipes, or fittings.
Beyond infrastructure concerns, consistently acidic water may also impact dental health, making proper pH management an important part of protecting both your system and the people who rely on it.
This can be achieved by introducing alkalizing minerals such as baking soda (sodium bicarbonate), granulated calcium carbonate (calcite), or sodium carbonate (soda ash). Among these options, baking soda is most commonly used due to its availability, affordability, and predictable performance. UTCW Acid Rain Mineral Pack is also a good way to balance pH.
Baking soda acts as a safe neutralizer, allowing pH adjustment without the risk of excessive elevation. However, as noted by Patricia Macomber of the University of Hawai‘i College of Tropical Agriculture and Human Resources, determining the correct dosage is not one-size-fits-all. Each catchment system is influenced by variables such as rainfall patterns, tank volume, roof materials, and existing water chemistry.
When adding chlorine and/or baking soda, always dissolve the material in water first. Pour the solution into the tank and stir thoroughly to ensure even distribution throughout the stored water. A pH of 7.0 is considered neutral. The ideal range for household water falls between 6.5 and 8.5, with a strong recommendation to maintain pH above 6.5 to reduce corrosion and metal leaching—particularly in systems with metal roofing, pipes, or fittings.
Beyond infrastructure concerns, consistently acidic water may also impact dental health, making proper pH management an important part of protecting both your system and the people who rely on it.
Water Testing for Private Water Supplies
If You Don’t Get Your Water from a Public Utility, It’s All on You.
If your household water comes from a rainwater catchment system or private well—not a regulated public supply--you are the Water Department. It is solely your responsibility to ensure your water is safe to use and safe to drink.
Routine water testing isn’t optional—it’s essential.
Even if your water appears clean and meets safety standards today, regular testing creates a documented history of your water quality. That record is critical when troubleshooting future issues, tracking changes, or protecting your health.
Test for key contaminants such as:
- Bacteria (E. coli, total coliform)
- pH levels
- Heavy metals (lead, copper, zinc)
- Turbidity and mineral content
For more information on local Hawai'i water testing:
www.tiloscleanwater.com/clean-water-partners.html
www.tiloscleanwater.com/clean-water-partners.html
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