Is rainwater safe to drink?

My main objective in writing this article is to establish that rainwater is safe for any purpose, especially for non-potable uses such as irrigation, toilet flushing, and doing laundry but also as a drinking water source.  I will do this by focus first on captured rainwater for potable use with the idea that if it’s OK to drink, it’s OK for everything else.

Captured rainwater actually already is the primary drinking water source for millions of people now in the U.S. and its territories.  Does that mean that it is actually safe?  Of course that is not automatically true.  There may be immediate (acute) or latent (chronic) health effects of using rainwater, treated or untreated, for potable uses. This article intends to point out the benefits of potable rainwater as well as indicate the lack of any evidence of any negative effects of using rainwater as a potable water source.

Rainwater captured from private property rooftops is currently, and has been used for hundreds of years, as a drinking water source.  I am personally unaware of any reports from anywhere of any negative effects from using this water source.  I have on the other hand heard and read about many reports of municipal water sources causing serious acute health issues.  The cryptosporidium outbreak in Milwaukee in 1993 is one example where people became seriously sick from municipal water supplies.  In that extreme case, it is reported that over 1 million people became ill and 104 people’s deaths were attributed to the water issue. In many more cases E. Coli is detected and reported in municipal water supplies.  While this does not automatically indicate that this water was unsafe to drink, it usually did result in water boiling requirements for local residents and definitely exceeded EPA standards.  The risk of acute issues with municipal water supply remains a concern even though most of us do not worry about this.

Before I launch into my evidence in support of collected rainwater as a viable potable water source, I must point out that municipal water supplies have greatly improved our level of health over the last 100+ years.  Clean drinking water from waterways and groundwater were greatly improved with modern treatment and better water management practices. Before that, lack of knowledge of possible pathogens and know-how to create clean water out of dirty water sources led to many problems.  However, the trend to use surface and groundwater as a large scale water source does not negate the viability of rooftop collected rainwater as a viable, safe drinking water source.

In contrast, there is no data and no instance of acute problems from drinking collected rainwater of which I am aware.  I would love it if someone would contact http://www.ecovierain.com to give any instance where this has occurred in the U.S. or anywhere in the world.  On the other hand, we do have our anecdotal and scientific research which indicates that collected rainwater is totally safe to drink and offers as low or lower risk of acute health issues than municipal water supplies.

Ecovie has installed several potable rainwater systems.  Check out our website for examples.  In each case, we tested the water before and after treatment and in every case found treated water to meet EPA drinking water standards.  In many cases the untreated water also met EPA standards.  See http://bit.ly/WFIaxI. I think that is fantastic, but it a limited sample size.  There is one study done in Australia which uses a larger cohort.  See http://bit.ly/11Kyari.  Over one year, there was no statistical difference in occurence of gastrointestinal issues between households which had rainwater systems as the sole drinking water source WITH AND WITHOUT treatment.  Please ask us if you want to see the full university report.  The Ecovie results and this one university study still does not prove that it is impossible to become sick from rainwater.  Even the thousands of rainwater systems from rural Kentucky to Texas to Hawaii to U.S Virgin Island and Puerto Rico to not prove that.  But, that fact that none of these example indicate any risk of acute issues from rainwater is a pretty strong indication that the risks are minimal.  In contrast, the ongoing examples of risk and actual incidents with municipal supplies indicate that rainwater may actually be a safer water supply.  Again, I ask you to send me real and verifiable data for specific examples of acute issues with rainwater collected from rooftops.

Now, let’s talk about chronic effects.  Are there any long term documented effects of drinking any type of water? Most of us have heard about the contaminants that exist in our municipal water supplies.  From runoff of pesticides and fertilizers in surface sourced water supplies to chromium-6 detected in many cities’ water supplies, the potential risk has been raised.  The chomium-IV contamination made famous by Erin Brockovich nor the PCE and TCE well contamination at Camp Lajeune, NC in the 1950’s to 1980’s causing alleged cancer cases do not have definitive direct proof of a link to chronic heath issues, but have raised concerns to say nothing about the court awards. Please check out Wikipedia and others sources to draw your own conclusions. I personally strongly suspect that the link exists, but being the scientific type I will not write or say that actual proof exists.  But, what is the actual level of risk to you regardless of what your water supply is?  The above examples indicate possible chronic risks from municipal water supplies albeit without definitive cause and effect links.

What about collected rainwater?  We can measure a wide range of contaminants in municipal water supplies and can prove how they came to be there.  With collected rainwater, none of these contaminants have been detected to my knowledge and we know that by the nature of the source of collected rainwater that the possibility that these types of detecting contaminants is an order of magnitude more remote than water coming from surface water (runoff to reservoirs or rivers) or from groundwater (wells).  Since rainwater never touches the ground, it cannot accumulate unwanted contaminants that are found from runoff.  For the same reason, rainwater cannot be accumulate many of the same contaminants that can seep into groundwater supplies.  Rainwater collected from rooftops by design avoid most of the risks to water quality found in our normal municipal water sources.

Does that mean that collected rainwater is automatically free of risk from contamination for either acute or chronic agents?  Of course not.  Nothing I can think of is completely free from risk from anything.  Risk is a relative term.  It is riskier to drive your car from Atlanta to Chicago than it is to fly.  Using collected rainwater for any use, especially non-potable uses but even for drinking water (in my opinion) is less risky than using municipal water supplies.

Now I would like to cover a bit about non-potable water uses.  There are a lot less concerns about water quality with water used outdoors for things like irrigation.  Nevertheless, we have heard about worries about sprayed rainwater being inhaled or about someone drinking water from a non-potable spigot.  Given that it is likely that the water meets EPA drinking water standards, this concern is minimal. Again, there are no reported incidents of anyone experiencing acute symptoms from inhaling or drinking captured rainwater.  On the other hand, wells and surface runoff sources are not controlled for water quality when used for non-potable irrigation use.  Now, let’s cover indoor use.  One concern is that piping indoors, specially in large institutional and commercial buildings will be confused with a potable water pipe and linked in sometime in the future.  This is a valid concern and I agree with backflow and pipe indication measures that prevent confusion and inadvertent mistakes, although the actual risk may be minimal.  I do not agree with measures like labeling toilets as supplied with non-potable rainwater which is the case in many areas.  The risk I have heard that a pet may drink from a toilet.  While this may happen from time to time, the potential risk from fecal coliforms we humans put directly in said toilet is far greater than contamination from rainwater.  The same argument holds for water splashing up on your butt after a particularly satisfying trip.  Again, risk is relative.

At Ecovie, we match treatment regimen with the end use to assure clean, pure water that meets the needs of our customers.

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2 Responses to “Is rainwater safe to drink?”

  1. Tom Barrett Says:

    Bob,
    I do not recommend collecting rainwater from roofs with asphalt shingle or any surface covered with bituminous materials for potable water use.
    Nice article.
    Have you seen any of the work on atrizine contamination in domestic municipal potable water supplies? Atrizine is banned in Europe but widely used in the U.S. Here is a link for more information:
    http://graphics8.nytimes.com/packages/pdf/us/NRDC-Atrazine-report.pdf

  2. bobdrew Says:

    Thanks for your comments Tom!

    I am aware of the concerns about asphalt shingles. We have installed two potable systems using water collected from roofs with asphalt shingles. Tests results show no issues. In addition there was a university study done in Germany to test the affects of asphalt shingles. The results showed no statistical difference between roofs with and without asphalt shingles. This report was pointed out to me by a microbiologist with the EPA who specializes in drinking water. Because of that report, we included asphalt shingles as allowable roofing materials for in the Atlanta potable rainwater ordinance.

    I had not heard about the concern about atrazine, so thanks for pointing that out!

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