Rain Barrels to Water Vegetables?

Hi Angie,

All the data I've come across has also provided conflicting information so when we get this question from residents and community gardens The City of Calgary recommends using a rain garden only to water flower gardens, lawns,trees, and shrubs (non-edible crops) until we can gather more conclusive information one way or the other. If they choose to use it on vegetable gardens they do so at their own risk.  

If someone is really keen they can have their rain barrel water tested by the local healthy authority to determine if its safe or not. This may help with asphalt contamination, but is only as accurate as how clean the roof is kept.

The City is hoping to do further study into this, but haven't started anything to date.

Amy Carton
Water Educator
The City of Calgary
Canada
calgary.ca/waterservices

http://home.comcast.net/~leavesdance/rainbarrels/safety.html

[quote]Summary: The consensus is that there is not a clear consensus. There are significant and reasonable concerns about using rooftop harvested rainwater for drinking or watering food plants. To paraphrase a famous adage: Caution is the better part of good health. You'll have to weigh this information and should probably gather more before making your own choices and decisions. There are many variables to consider, including what part of the country you live in and what your roof is composed of. You can certainly have your water tested, though I suspect that is a costly procedure. [Note: If you can send or direct me to evidenced findings specifically about the use of rooftop harvested rain on edible plants by a credibile source, I would appreciate it.] [/quote]

Consensus seems to be that it depends on the type of roof, what might be living on it, where you live, etc.

Steel roof, upstream of a city and factories, without critters living on the roof, would appear to be safe.


Norm Ruttan
President
iWasteNot Systems
Canada
www.iwastenotsystems.com

My biggest concern about rain water application to fruits and vegetables is application to edible portions of the plants with water that may contain harmful bacteria. Because birds, squirrels and other animals defecate on roofs, the water may pick up those harmful bacteria. This can be especially problematic on coastal homes where many seagulls or other birds land on roofs constantly and in large numbers.

I'd hate to be the person that tells a large group it is okay and then find out someone was sickened by the practice.

Gary Fish
Manager, Pesticide Programs
Maine Board of Pesticides Control
United States
http://www.YardScaping.org

Rainwater is easy enough to purify for the purpose of using on plants by using a first flush diverter and then some small level of prefiltration if the water is touching the fruit or if they are root crops. Otherwise, the divertor, mulch, soil and roots will do a fine job of cleaning whatever might be left in the water. Rainwater is soft and has more oxygen than treated water and your plants will love it.
Here is a page with extensive info on rainwater filtration and rainwater quality:

http://www.whollyh2o.org/waterquality/item/122-rainwater-quality-and-filtration.html

Hope this helps.

Elizabeth

Elizabeth Dougherty
Director
Wholly H2o
United States
www.whollyh2o.org

Hi Elizabeth,

Rainwater is soft and wonderful, but if it hits a roof that is covered in bird feces that contain salmonella, I am not sure that filtration will do the trick. It will require UV treatment or reverse osmosis to take out the microscopic bacteria.

If I water my garden with water from my rain barrel that is full of harmful bacteria and that water goes on tomatoes that I harvest right after watering I may end up sickening myself and my family. I do not think it is a good idea for us to recommend that someone water their vegetable garden with water from a roof unless they drip irrigate or only water the root systems and never allow the water to contact ripe food surfaces.

Even you web site says that rain barrel water must be treated before it is potable and only potable water should be applied to edible portions of plants if they are to be harvested immediately.

We see too many people sickened across our country because people do not recognize the risks from microbial sources of contamination. They over-react to pesticide residues and under-react to biological threats. Think of spinach.

Gary Fish
Manager, Pesticide Programs
Maine Board of Pesticides Control
United States
http://www.YardScaping.org

This is really great information for most of the world. But I want to throw a cautionary note about the western United States.

There is a unique body of law called Water Law which has its own court system to cover the collection, distribution and use of water in the arid landscape. In most of the states where this law exists, rain barrels are illegal.

When Sandra Day O'Connor was retiring from the US Supreme Court, she urged the President to appoint another westerner, familar with this law. The reason being that the most far reaching court decision of the 21st Century was likely to be about water rights coming from this arcane body of laws.

Richard Knaub
Director of Education Programs
Veterans Green Jobs
United States

Here are a few useful reports that speak to pathogens in rainwater and bmps:
http://www.rainharvesting.com.au/rainwater_research.asp
enhealth.nphp.gov.au/council/pubs/documents/rainwater_tanks.pdf
http://www.irc.nl/page/29189

If you properly maintain your collecting and filtration system, you will find yourself to use the water as desired on food crops.


Elizabeth Dougherty
Director
Wholly H2o
United States
www.whollyh2o.org

The key to your response is that the collection system have filtration and that it be maintained. At this point in time in most of the rain barrels I have ever seen, there is neither filtration nor any real maintenance. Hence my recommendations stand, use the water on non-edible plants or keep it on the root systems. You must not live in an area where seagulls and other marine birds make a real mess of people's roofs.

Gary Fish
Manager, Pesticide Programs
Maine Board of Pesticides Control
United States
http://www.YardScaping.org

Gary:

I live in the area of the largest estuary on the western side of North and South America, (SF Bay Delta)and therefore many many birds. We just teach people how to maintain their rainwater harvesting systems safely and legally.

Here in California, we HAVE to begin using rainwater for both outdoor and indoor use if we are going to maintain water security. Therefore we are agressive in learning how to manage it correctly.

Best,
Elizabeth

Elizabeth Dougherty
Director
Wholly H2o
United States
www.whollyh2o.org

Greetings...This is an excellent site! I'm going to add some of the information from here to our safety page.

I just wanted to update y'all on our popular "build your own" rain barrel website's new location:

http://tylertork.com/diyrainbarrels/construction.html

Also on our site's safety page is a link to a site detailing the making and use of a bio-sand filter system; at the bottom of this page: http://tylertork.com/diyrainbarrels/safety.html

Happy Watering!

Rebecca C.
United States