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  • Writer's pictureGary Moller

Is Drinking Water off a Roof Harming your Health?

Updated: Apr 5

(Updated: October, 2023)

The Story in a Glance

The rural lifestyle, with its picturesque surroundings and natural charm, is a dream for many. However, there's an overlooked threat that could affect the health of rural families: drinking rainwater collected from rooftops. Extensive testing through Hair Tissue Mineral Analysis (HTMA) consistently reveals elevated levels of various minerals in water, including copper, iron, manganese, and more. These elevated mineral levels have alarming health implications, from cognitive impairments to long-term illnesses, often with subtle symptoms initially. Even low toxin levels can pose risks when combined with other contaminants.

Rainwater, slightly acidic due to a pH of around 5.5, becomes a concern after dry spells. Salt from ocean winds settles on rooftops, typically made of metal coated with paints containing metals like titanium and lead. In the scorching sun, these metals transform into soluble mineral salts, which are flushed into tanks during the initial rain after droughts.

Families then use this tainted water for various purposes, raising serious health concerns.

To address this, rural residents can explore alternative water sources, differentiate usage of collected roof water — install "First Flush" systems, prioritise effective filtration, and consider the timing of rainwater collection. Vigilance is also required regarding potential contamination from other sources.

Swift contamination can overwhelm the body's detoxification mechanisms, making it crucial to avoid drinking contaminated water, especially after dry spells. Vulnerable groups, like children and women, may be more sensitive to toxins. In cases of concern, conducting HTMA tests on household members can provide insights into contamination levels, guiding detoxification efforts and confirming contamination before costly water supply upgrades.

In conclusion, protecting the health of rural communities is paramount. Regular water testing, awareness of contamination risks, and proactive measures are vital for safeguarding water sources and protecting the well-being of rural families.

Hair tissue chart
An example from a "tired" farmer and hunter who has been taking water off rooftops.

Note: Arsenic is elevated in the above HTMA example. This is because the rural lifestyle brings people into contact with arsenic-treated timber, such as with fence posts.



The rural lifestyle has undeniable charms — fresh air, abundant sunshine, home-grown food, and clean water, among others. It all seems idyllic, but is there an unseen threat lurking in the pristine countryside that could jeopardise the health of rural families?

I'm talking about drinking rainwater collected from rooftops. After conducting numerous hair tissue mineral analysis tests (HTMA), a consistent pattern emerges — elevated levels of various minerals, including copper, iron, manganese, chromium, cobalt, molybdenum, arsenic, cadmium, lead, aluminium, rubidium, lithium, nickel, vanadium, tin, titanium, and tungsten.

But what's concerning about these elevated mineral levels, you ask? Well, they're associated with a wide range of health issues, from mental impairments to dementia. These effects can take years, even decades, to manifest as a full-blown illness. In the meantime, individuals may experience vague symptoms like unusual fatigue, skin problems, mysterious aches, and pains, or memory lapses — symptoms often overlooked or attributed to other causes.

Even when a toxin's level appears low, it can have a significant impact on health when combined with other toxins, including excessive levels of "nutritional" elements like iron.

For example, arsenic exposure may be linked to treated timber, such as fence posts, or soaking in geothermal hot pools. Aluminium, often used as an anti-caking agent in fertilisers, and cadmium, a contaminant in super-phosphate, can also contribute to contamination. Surprisingly, lead exposure may not be limited to anti-corrosive paints but may even involve everyday items like firearms, including children's airguns that fire lead pellets. However, these explanations, while relevant, don't fully account for the extent of mineral contamination observed.

After conducting numerous tests and scrutinising various factors, a significant source of bodily contamination has come into focus: the consistent factor among many cases is a history of consuming rainwater collected from rooftops. Let's delve into what's happening here.

Rainwater tends to be slightly acidic, with a pH around 5.5 (7.0 being pH-neutral). Picture a summertime scenario after a prolonged dry spell, even a drought. Much of New Zealand is exposed to salt carried by the wind from the ocean. This salt settles onto rooftops, typically made of metal and treated with anti-corrosive paints. Interestingly, some of these metals, like titanium and lead, serve not only as effective anti-corrosives but also as pigments, making them common rooftop components. Bear in mind that the roof may have had a dusting of fertiliser from aerial top-dressing as well.

Under the relentless NZ sun and in the presence of salt, the minerals in paint and metals undergo a transformation into soluble mineral salts. Overnight dew and occasional light showers facilitate this process. Meanwhile, the rainwater storage tank approaches depletion. Then, when it finally rains, the initial runoff carries a concentrated solution of these toxic mineral salts into the tank. This tainted water is then used by families for drinking, cooking, and bathing — a practise that raises serious health concerns.

We may, therefore conclude that, while the rural lifestyle offers numerous benefits, it's crucial for those relying on rainwater collected from rooftops to be aware of potential health risks, and to do what they can to mitigate its potential to cause harm. As our analysis shows, this water source may not always be as pure as it seems, and understanding the underlying hazards is essential to safeguarding the health of rural communities. So, what can rural people do about this hazard?

Testing your water for toxic elements is a crucial step in protecting the safety and quality of your water supply. However, it can be challenging due to several factors:

  1. Toxic Buildup: Even minimal exposure to highly contaminated water can lead to toxic buildup in the body. These toxins can remain hidden within organs for extended periods, gradually affecting your health over time.

  2. Rainwater Dilution: Rainfall can dilute water samples, masking the presence of toxins. To get an accurate assessment, it's best to collect and test the water after an extended dry spell, especially if you rely on rainwater harvesting.

  3. Location Matters: The timing of sample collection isn't the only factor to consider. The location within the water supply chain can also influence the presence of contaminants. Water that sits stagnant or is exposed to certain materials, like metal in tap fittings (some of which may contain lead), may become contaminated.

Here's a helpful tip: If your water has been stagnant for a while, such as overnight or after returning from a holiday, it's advisable to run the taps for a few minutes to flush out any stagnant water from the immediate pipes and fittings before using it for drinking or cooking. This precaution also applies to holiday homes and remote huts.

If you're on roof water, regular water testing and vigilance in checking the quality of your water source are essential steps in safeguarding your health and well-being.

Mitigating Hazards: Protecting Rural Water Quality

While addressing the hazards associated with rainwater collected from rooftops in rural areas may not offer simple solutions, there are several considerations that can help reduce exposure to these toxins. Here's what rural residents can explore to safeguard their water quality:

  1. Alternative Water Sources: Investigate alternative water sources like springs or boreholes. These sources may offer a cleaner and more reliable supply, reducing reliance on contaminated rainwater.

  2. Differentiate Usage: Reserve collected roof water for non-drinking purposes, such as washing, cleaning, and irrigation. While it might not be suitable for consumption, it can still serve various household needs without posing the same health risks.

  3. First Flush Systems: Install a "First Flush" system, like those available from Marley. These systems help divert the initial runoff after dry spells away from the storage tank, reducing the concentration of contaminants in the collected water.

  4. Effective Filtration: Prioritise water filtration to address both pathogenic microorganisms and toxic elements. Filtering rainwater can be complex, considering factors like water pressure. Consulting experts, such as the Filter Warehouse, can provide valuable guidance on selecting and installing suitable filtration systems.

  5. Time Matters: Assess the timing of rainwater collection. Water collected after several days of consistent rainfall is less likely to contain concentrated contaminants. Regular flushing of the water tank during rainy periods can further minimise the risk.

  6. Other Sources of Contamination: Be vigilant about potential contamination from other sources, such as water from shearing sheds, holiday homes, or backcountry huts. Consider alternatives such as a high-country stream, or bring your water with you. Don't drink water collected from sources that have concentrations of animals above or nearby. This means most lowland rivers in NZ are undrinkable without being treated first.

Warning: Protecting Health from Rooftop Rainwater Hazards

It's crucial to be aware of certain warnings when dealing with rainwater collected from rooftops in rural areas. Understanding these potential risks and taking appropriate precautions is essential for safeguarding your health and that of your loved ones:

  1. Swift Contamination: Contaminated rainwater can overwhelm the body's natural detoxification mechanisms in just one or two instances of consumption. The extent of contamination depends on factors such as the concentration of toxins and the timing of collection. It's imperative to avoid drinking contaminated water, especially the initial runoff following an extended dry period.

  2. Vulnerability of Specific Groups: Children, adolescents, and women may exhibit increased sensitivity to these toxins compared to men. Children, in particular, are considered accumulators of environmental toxins, making it crucial to shield them from exposure to substances like lead and cadmium.

  3. Accumulation in Organs: If the body can't expel toxins promptly through mechanisms like urination, bile secretion, perspiration, and the natural shedding of hair, skin, and nails, it'll sequester excess toxins in organs such as the liver, kidneys, adipose tissue, bones, and even the brain. This accumulation can lead to unsafe levels of toxins like cadmium, emphasising the importance of avoiding prolonged exposure.

Test your Family

If you have concerns about the potential health impact of contaminated water, whether it's an ongoing issue or a historic one, it's advisable to consider the following steps:

1. Test Your Body: Consider conducting a Hair Tissue Mineral Analysis (HTMA) for yourself and other household members. HTMA is a highly accurate method for detecting signs of bodily contamination by toxic elements. It can provide valuable insights into the presence of toxins in your system.

2. Act Based on Results: If the HTMA results indicate contamination, it can serve as a guide for taking appropriate steps to safely remove toxins from the body. Tracking progress through repeated testing is also crucial in assessing the effectiveness of detoxification efforts.

3. Confirm Contamination Before Upgrades: If you're contemplating costly upgrades to your water supply due to contamination concerns, it's wise to perform HTMA testing first. This will help confirm whether there is indeed contamination affecting the health of individuals in your household. If no contamination is found, you may save yourself unnecessary expenses.

While implementing protective measures can significantly reduce the health risks associated with rainwater consumption, it's essential to seek expert guidance and regularly test your water to ensure its safety and quality. Prioritising proactive measures to safeguard your water source is an invaluable investment in your family's well-being. Your health should always be the top priority, and preventive actions can play a pivotal role in maintaining it.

In Conclusion

While the rural lifestyle offers numerous benefits, it's crucial for those relying on rainwater collected from rooftops to be aware of potential health risks and to take steps to mitigate this hazard. As many HTMA analysis have shown, this water source may not always be as pure as it seems, and understanding the underlying hazards is essential to safeguarding the health of rural communities.

Testing your water for toxic elements is a crucial step in protecting the safety and quality of your water supply. However, water testing can be challenging due to factors like toxic buildup, rainwater dilution, and location within the water supply chain. To mitigate these challenges, consider alternative water sources, differentiate water usage, instal First Flush systems, and invest in effective filtration.

Additionally, remember that swift contamination can overwhelm the body's natural detoxification mechanisms, making it imperative to avoid drinking contaminated water, especially the initial runoff following an extended dry period. Vulnerable groups like children, adolescents, and women may be more sensitive to toxins, emphasising the need for caution.

If you have concerns about the potential health impact of contaminated water, consider conducting a Hair Tissue Mineral Analysis (HTMA) to detect signs of bodily contamination by toxic elements. Act based on the results, and confirm contamination before making costly water supply upgrades.

Protecting your family's health and well-being should always be a top priority, and taking proactive measures to safeguard your water source is an invaluable investment in maintaining a healthy rural lifestyle.

432 views2 comments


Kiwi Cam
Kiwi Cam
Oct 07, 2023

I'm also concerned about what we're NOT testing for. I don't know what paint is made of (doubt there is lead in modern paint), but I sometimes see a green coloured sludge in the first leaf filter which is the same colour as the roof paint and wonder what chemicals are in that. Polymers/plastics? The low pH of rainwater will leech the copper from copper pipes and give a blue/green stain. We have high pH bore water, so we sometimes mix the too which eliminates the visible copper issue. It seems we should be focusing more on fully filtering our water and town supply has toxic chemicals too. Not to mention a lot of mismanagement, but we won't go there.

Gary Moller
Gary Moller
Oct 09, 2023
Replying to

You're absolutely on the money, Cam.

Its anybody's guess what's in the roof materials on a person's roof, so testing is important but it can be problematic, as oultlined in the article.

By the way, manganese and iron may leave a brownish stain on porcelain.

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