Asphalt shingles and catchment??

[AKpilot]

One of my structures catches water off of a Asphalt roof. I put it through 2 micron filters and a UV light. I don't drink it, but a friend suggested that the petrolium products are removed via the filtration process. I drink off of my metal roofed catchment....filtered the same way by the way.

AKpilot

We're all here, because we're not all there!

[EightFingers]

Several houses with asphalt shingles here. Haven't head of issues with catchment. I know of one for sure that drinks the water. Maybe the granules act as a filter of sorts. For me, I wouldn't do it.

[geochem]

VERY BAD IDEA. Under no circumstances would I drink or cook with water from a roof catchment fed by asphalt shingles (I wouldn't even make a habit of showering in water from asphalt shingles). The only way I would consider it is if there was an activated carbon filtration system on the water coming into the house - and even then, I would want to check the water on a regular basis for dissolved petroleum hydrocarbon leakage through the filter. Asphalt is a stew of hydrocarbons and contains significant fractions of "polycyclic aromatic hydrocarbons" that can generate a host of health problems when ingested (http://superfund.oregonstate.edu/superfu...about-pahs).

This isn't the kind of thing that you will immediately see problems - but ingestion of these compounds could significantly increase your statistical risk of (a host of) cancer(s) after long term, low level, exposure. For some sensitive individuals, it's also possible that they will develop an allergic reaction to these compounds as a result of long term dermal exposure.

[terracore]

"Asphalt Shingle Roofs

Asphalt fiberglass shingles are the most commonly used roofing materials out there, so odds are this is what you’ve got to start with. A lot depends on how old the roof is. New asphalt shingles produce water with a high concentration of dissolved organic carbon (DOC), which are molecules found naturally in bodies of water. In general DOC isn’t very harmful, but when combined with Chlorine, a chemical frequently used to disinfect water, DOC produces chemicals that can cause cancer if ingested. After one year, the concentration of DOC decreases to more normal levels, however, other pollutants like particulate matter, zinc and iron increase as shingles age.

Around here, many asphalt shingles are treated with a moss killer, which will complicate rainwater harvesting. Moss treatments generally contain zinc and copper which will pollute your water.

If you have an asphalt roof that was installed before 1980, my guess is that you know just by looking at it that you should not be drinking what comes off of it. Aside from being severely deteriorated, thirty-three-plus year old shingles may contain asbestos, a toxic fiber widely known to cause mesothelioma and other cancers. Shingles made since then are asbestos free."

http://www.pacificwestroofing.com/blog/t...-rainwater

“We have been researching and sampling raw rainwater from asphalt shingle roofing and have found that rainwater is ideal for deionization and, along with other filtration and UV disinfection, we can produce ultra pure water of laboratory quality”, explains Ken Blair. “This process allows those with this type of roofing material to enjoy the benefits of rainwater collection.”

https://rainbank.info/can-you-collect-po...ngle-roof/

Municipal water in most of the country starts out as rain, some of which comes off asphalt roofs and streets that eventually gets dumped into a river to be used downstream by another community. It is unlikely that anybody on the mainland has never drank water that didn't at least a minute quantity of water that had contact with some sort of asphalt product. I remember the water in Oklahoma City was so putrid it practically had to be chewed.

I think with carbon filtration I would be comfortable bathing etc with the water so long as the shingles aren't brand new or ancient old. What is most important for leeching chemicals is the duration of time the water has contact with the substance. So long as your roof isn't ponding water the water will be spending the majority of it's time leeching from your catchment liner. You could always send a water sample out to be tested. I have a TDS meter and while it only tests for dissolved solids our catchment water tests cleaner than both municipal water and name-brand bottled water. I probably wouldn't DRINK the water without a test result, but that's probably just personal preference.

[ericlp]

dunno... while probably not a good idea... I can't imagine that while as pointed out, a commonly used roofing material... There must be billions of sq ft of roofing that is getting rained on daily and billions of gallons of fresh water hitting those roofs every day/night getting saturated. Oahu and Maui probably have more asphalt roofs than metal ones. My roof is asphalt, but I got private water. Point is, many animals and bugs are consuming all that water and ... that runoff undoubtedly going into the ground to become drinking water for millions of people. Filter or not, I think you'd be fine to shower in it or wash up dishes ... But drinking or cooking with it... maybe not. Your choice I guess.

[Carey]

the CTAHR Catchment booklet advises against roofing materials that can have asbestos and asphalt (many Asphalt shingles have used asbestos as a fire retardant in the past):
http://www.ctahr.hawaii.edu/oc/freepubs/pdf/rm-12.pdf