Rain water collection for drinking with questionable roof material

I have a metal roof with ( APOC 243 4.75-gallon White Elastomeric Reflective Roof Coating ) on it to keep the interior cool.

Is this stuff as bad as asphalt roofing for rainwater collection? From the researching ive been doing asphalt shingled roof is a big no-no and leeches chemicals that filters wont remove (such as a berkey). Ive read the datasheet on this product but it does not tell me as a laymen anything and the company wont respond, but does have a lot of scary chemical names in it.

Would you drink filtered water with a roof with such a coating or am I overthinking this? Ive still been using unfiltered roof water collected to do dishes / wash, etc but not drink.

Having a rough idea of your location would help.  Assuming you are in the USA,I would contact an organic Chemistry instructor at the nearest state university and ask this question.  I have had good results with 5his sort of approach.

Cameron Miller wrote: Would you drink filtered water with a roof with such a coating or am I overthinking this? Ive still been using unfiltered roof water collected to do dishes / wash, etc but not drink.

The Safety Data Sheet lists the reflective components in detail, and I think those could be filtered out. (Titanium Dioxide, limestone, silica crystalline - quartz, kaolin - a bentonite clay)

But as far as I can tell it doesn't talk about the elastomeric (rubberizing) components, and personally I think that's the wild card. My guess is this is a sort of flexible plastic glue that holds it on the roof surface. As a rule the more flexible a plastic is, the less healthy it is. So I would be cautious.

Personally, in an emergency/short term situation I would let the rain wash off the roof and then collect the water for filtering/boiling. For long term use, I would set up a separate collection system with a different roofing material. My 2c.

If you are bathing in, washing cloths and or eating off of dishes cleaned with that water, you are already exposed to it.
I would check what kind of standard Australians use for roof coatings and see if your coating is up to snuff.
They are big on drinking roof water, and they seem healthy enough.

I think the hydrocarbons from a  shingle roof can be removed via filtering, via reverse osmosis if not something simpler.
Any plasticizers in the roof water should also be filterable

From my memory of using elastomeric paint on my roof in Tucson, it was basically a thick latex paint. I collected lots of rainwater there (for plants, not drinking) and it was good quality -- no off smell and attractive to bugs if I left it uncovered. The roof paints that are sold here (NZ) are acrylic latex and most, if not all, are labelled as being drinking water safe. You might be able to ask the manufacturer, or have some captured water tested.

In Australia most coloured roofs would be created with 'Colorbond' treatment, which is water safe.
The material is now being sold in North America.
As for your issue, I think the advise given is good.
A google search found this
"No, APOC 243 is not safe for drinking water collection.
The official manufacturer product safety documents explicitly state: "Do not use in drinking water or food systems".
Chemicals, polymers, and biocides from the coating can leach directly into the runoff water, making it toxic for human consumption.
Essential Safety CertificationsTo collect drinking water from a roof, you must choose products that carry specific public health and safety certifications:
NSF/ANSI Standard 61: Certification for drinking water system components.
NSF Protocol P151: Health effects evaluation specifically for rainwater catchment system components.
Safe Alternatives for Drinking Water CollectionIf you must coat your metal roof and intend to harvest drinking water, you will need to completely pivot your strategy to alternative systems or materials:
Potable-Safe Coatings: Specialized products—such as Weather Barrier 2000 Rain Coat—are explicitly manufactured and certified under NSF P151 for drinking water catchment.
Bare Metal Surfaces: Safe, unpainted steel roofing panels such as COLORBOND® or ZINCALUME® are widely approved for harvesting drinkable rainwater.
Avoid lead flashings and lead-based paints entirely."

John C Daley wrote:A google search found this
"No, APOC 243 is not safe for drinking water collection.
The official manufacturer product safety documents explicitly state: "Do not use in drinking water or food systems".

I am as sceptical as you. However, the documents I can find from the manufacturer at apoc.com do not appear to contain this statement.  It's a mystery -- I am not sure where this comes from?

Douglas Alpenstock wrote:

John C Daley wrote:A google search found this
"No, APOC 243 is not safe for drinking water collection.
The official manufacturer product safety documents explicitly state: "Do not use in drinking water or food systems".

I am as sceptical as you. However, the documents I can find from the manufacturer at apoc.com do not appear to contain this statement.  It's a mystery -- I am not sure where this comes from?

I don't trust anything coming out of Google now. I stopped using it years ago and this could very well be an AI hallucination, especially since there is no citing of the source and it differs from the manufacturer's advice.

AI is peeing in the pool, tainting everything it touches and it's too bad that we now have to go to lengths to avoid it or fact-check it aggressively. I miss the old internet when search engines prided themselves on returning relevant results.

I may stand corrected, but I have not seen those issues.
Here is a further link https://pdf.lowes.com/productdocuments/121aa11b-b343-4f91-80aa-0b580cc43b30/47616957.pdf

that specifically states
"PRECAUTIONS: DO NOT allow product to freeze.
Protective clothing, gloves  eyewear should be used during application of these products.
When transporting this product, ensure that lid is tight & pail secure & upright.
DO NOT allow pail to tumble as this may cause lid to loosen and leakage to occur.
Do not transport on passenger seats or inside the passenger compartment
of any vehicle. Store product in the cargo area of vehicle, and secure over
protective cloths to prevent damage due to accidental spills.
For longest life, store in controlled environment, 35 °F - 80 °F. Do not store in direct sunlight.
Close container after use.
Do not use on EPDM, TPO, PVC or other rubber/ synthetic surfaces.
Do not use on single ply or synthetic roofs.
If there is any question regarding compatibility to the roof surface, test a small section first
for proper adhesion.
Do not use in drinking water or food systems. "

I agree with John C. the product is definitely not suitable for collecting drinking water, per the MSDS.
If it is not suitable for drinking water, what is it doing to the ground water?
There are some really good quality roof paint products that are suitable as a surface from which to collect water.  We have had a colourbond roof for over 40 years and never had an issue.
I found this via Duck Duck Go AI.  Interesting note is that Permies.com is one of the sighted references

John C Daley wrote:I may stand corrected, but I have not seen those issues.
Here is a further link https://pdf.lowes.com/productdocuments/121aa11b-b343-4f91-80aa-0b580cc43b30/47616957.pdf

that specifically states
"...Do not use in drinking water or food systems. "

Thanks for the link, John C. It looks like the manufacturer  removed this statement in newer versions of their documentation (Technical Data Sheet and SDS). Or maybe it's still on the pail label. Regardless, if it was true in 2022 it is still true today.

Douglas Alpenstock wrote:

John C Daley wrote:I may stand corrected, but I have not seen those issues.
Here is a further link https://pdf.lowes.com/productdocuments/121aa11b-b343-4f91-80aa-0b580cc43b30/47616957.pdf

that specifically states
"...Do not use in drinking water or food systems. "

Thanks for the link, John C. It looks like the manufacturer  removed this statement in newer versions of their documentation (Technical Data Sheet and SDS). Or maybe it's still on the pail label. Regardless, if it was true in 2022 it is still true today.

Unless they changed the formulation, which is not out of the question. The ambiguity of the whole thing is what gets me. They should be clear about it and keep their documentation up to date, since people can and do use rainwater for domestic needs. Certainly in the teeth-gnashing realm, maybe not up to garment-rending levels.

Phil Stevens wrote:Unless they changed the formulation, which is not out of the question. The ambiguity of the whole thing is what gets me. They should be clear about it and keep their documentation up to date, since people can and do use rainwater for domestic needs.

True, though if they had a new formula that was rain-collection friendly, they would trumpet that in their marketing.

Once retailers start hosting documentation on their own sites instead of pointing to the manufacturer's site, it's impossible for the manufacturing company to control versions. That's hard enough to do within a single company with a single command structure (ask me how I know).

If I have any doubt, I do a search for the material data safety sheet (MSDS) or manufacturer's required data sheet.

It will be more work for you, but you could repaint the roof with appropriate coating.  Other options exist for keeping your interior cool, like healthy air space beneath the metal.  Also consider a safari roof if you need greater cooling