Blog Update!
For those of you not following me on Facebook, as of the Summer of 2019 I've moved to Central WA, to a tiny mountain town of less than 1,000 people.

I will be covering my exploits here in the Cascades, as I try to further reduce my impact on the environment. With the same attitude, just at a higher altitude!

Wednesday, May 30, 2007

Rain barrels and vegetable gardens

Rain barrel instructionsSince I've been planning on buying a rain barrel for a while now and I have it listed as one of my action items for Low Impact Week, I decided to do some more research on them before I buy.

One thing I ran across, for those of you out there that want to make your own, is this super nifty set of instructions that even I could do myself (with some additional tools). But, just when I was all ready to start planning my rain barrel production line, I ran across something that stopped me in my tracks.

According to this guide from Seattle Rain Barrel (see page 3), if you have an asphalt roof, you shouldn't use the water you collect for watering vegetable or herb gardens. Of course, that is what I was planning on doing with all this fabulous Seattle rain.

Apparently, a lot of modern asphalt shingles contain zinc, which produces toxic chemicals. Since our roof was replaced by the previous owner, I don't know whether or not it is safe.

Does anyone have any clue as to how to test whether my shingles will kill me if I use the collected water on my vegetable plants?


Niobium said...

I would call the roofer who put the shingles on the house if you know his/her name. Otherwise, call any roofer who offers free estimates and ask him/her when they come to do the estimate.

Kim said...

Oh no! I hadn't gotten that far in our research. Does anyone know what asphalt shingles look like? Are those the "normal" ones?

Thanks for letting us know.

Anonymous said...

probably the water isn't that good for you. Aside from the chemicals in the shingles, you've also got the stuff that settles on your roof due to air polution. I'm considering getting my rain water tested once I get my barrels up for the same reason.

Also, some places (sorry, no link) sell a diverter that will allow some amount of water to flow out the downspout and then switch over to the rain barrel - this theoretically washes the junk off your roof giving you cleaner water.

QT said...

Luckily, we have a tin roof! I hate it an want to replace it with a metal roof, but that is in the very - distant -future!

Greenpa said...

eeeeehhh. This is sounding like suburban legend, a bunch. I don't have a rainbarrel at the moment, but I grew up with one, and have kept an eye on the idea. I'd be surprised if the roofer knew off hand, but they should be able to at least get you the info on your shingles.

Zinc is a long way from being the worst thing out there- I have to ADD it to my soils for my crops. If you want to get it tested, it really shouldn't be that hard; ask your county agent first.

Living in sunny Seattle, you have the advantage of lots of rain- washing your roof frequently. That'll help.

A low tech pathway- set up the barrel, and leave the lid off. You'll get mosquitoes immediately, of course. But before too long you'll get other things too- like dragonfly larvae- and frogs. If you wind up with tadpoles living and growing cheerfully in your rainbarrel, I'd quit worrying- frogs are very sensitive critters.

Of course- that would take a year. :-)

Or you could send it to a little lily pond for a while- let the kids sail boats- watch the frogs.

The automatic diverter things CAN work nicely- good for washing bird poo etc. off the roof before you start collecting- but they are a mechanism that needs watching- the ones I'm familiar with can go out of whack fairly easily, leaving you with either no wash; or no water.

Have fun!

Anonymous said...

@greenpa - thanks for the reminder about the fish or frogs in the rain barrel. From what I understand, this is a fairly common practice in parts of South America - friends who've served in the Peace Corps tell of fish who both keep the bug population under control *and* provide a great way to check the safety of the water. Sort of a canary in the coal mine type of thing.

Crunchy Chicken said...

kmh - asphalt shingles are the "normal" ones. I think they are sometimes referred to as composite?

From what I was reading it's fairly common for people to put goldfish in their rain barrels to keep the mosquito population down. There are other things you can put in the water that will do that as well that, I think, are safe.

P~ said...

I'm not sure about the zinc in asphalt shingles, but my understanding of the composition of them is that they are essentially the same thing as an asphalt parking lot and contain all of the same oils and petrochemical compounds. I readily agree with the idea of a rain barrel, but would personally never use one draining off a Asphalt roof for anything but watering a lawn, or non-edible landscaping.
A possible fix though might be to place a couple of tracks of metal roofing or sheet metal on a particular part of your roof, and channel that water directly into your catch basin. I'm sure that in Seattle you wouldn't need a huge area to fill a barrel.
As far as mosquito abatement, there is a mosquito fish that a lot of cities will provide for free to owners of ponds, drainage ditches etc, that feeds primarily on Mosquitos, you should check into those. Also, Dragon flies are big mosquito eaters as well as also being waterborn insects.

Rechelle said...

Do you have a yippy dog in your neighborhood? One that like to bark all night long? That might be a good test subject for possibly poisonous water.

Kim said...

Well, this certainly changes some of our plans. We'll have to put our rain barrels by the metal shed instead.

We have been talking about putting a metal roof on our home when it needs to be redone. We are really working on making our home as sustainable as possible.

Our roof is only 11 years old. I wonder how much longer before we need a new one.

Thanks everyone for the ideas. This is what I love about the blogging community. Someone is sure to have answers!

Piddler said...

Well, I'm glad to know I shouldn't use it on my vegetables, but I still think it is a great idea for all my flowers and bushes up around the house. Get me a rain barrel and a soaker hose and I'll be set.

Anonymous said...

Interesting that my (desert) city's 41-page rainwater harvesting manual does not even mention this issue.

Greenpa, uncovered barrels of water are strongly discouraged locally due to the concern with West Nile virus transmitted by mosquitos. A friend's open rainwater barrel has not, over a number of years, developed a mosquito-controlling ecosystem. I know because I was bitten many times by the little bloodsuckers when I had to take care of watering her garden for 3 weeks a few summers ago!

Crunchy Chicken said...

Okay peeps. I contacted the experts and here's the deal.

As a general rule do not use water collected from asphalt roofs on your food crops.

In addition to the zinc leaching out, asphalt is a petroleum product and leaches other chemicals into the water. Asphalt roofs also are absorbent so they absorb pollutants, bird excrement and other things.

The sum of it all is that (for asphalt roofs) it's okay to use on your lawns or ornamentals but don't use it on plants you plan on eating.

If you want to chit-chat with an expert call the Natural Lawn & Garden Hotline at 206-633-0224.

P~ said...

So I got to thinking further about my suggestion to use a section of metal roofing to "clean catch" water for use with edible plants and wanted to add to it by mentioning galvanized steel roofing. The process of Galvanizing literally coats steel with a layer of zinc. There are powder coated roofing products, and aluminum sheeting products though that should be fine.

Anonymous said...

I have a question..hope this doesn't sound too dumb. We live in the country and have our own well. Now, it takes electricity to pump the water from the well, but we don't pay for the water like someone who lives in the city. We live on a lake and our yard is watered with water pumped directly out of the lake...again, the only cost monetarily is for the electricity to run the pump. Living just south of you in western Washington, we generally get lots of rain and only water the yard a couple times a week throughout the summer. I am interested in conserving and sustainability, but other than the electricity I'm using for the pumps, is there any reason to cut back on water usage? Like I said, hope this all doesn't sound really dumb and naive...I'm just learning!

Christy said...

Things like this make me feel so hopeless. I've been using a rain barrel for over a year and feeling good about it. Now, I may be poisoning my family by doing the right thing? Sometimes I really feel like I can't win. It is like trying to buy local, all I can get around here has been sprayed with pesticides and I don't want to feed that to my family, but I do want to buy local. Sometimes I think it would be easier to go back to eating Pop Tarts and frozen dinners. Sigh.

Crunchy Chicken said...

Christy - I'm sorry. You shouldn't feel hopeless. I think that the fact you've been using a rain barrel for the last year is fantastic. And, the studies at this point are inconclusive. So, I doubt you are poisoning your family. Just stop using it for food crops if you are in doubt.

Here's the information from the email I got from Seattle Tilth:

The issue that we have come across is not only with the asphalt roofs but also with many of the moss killers that folks use which contain zinc (and other nasty stuff) that comes off the roof during collection. Additionally many of the newer asphalt roofs in our area are made with zinc pellets injected into the shingles to try and reduce moss growth.

Obviously this leads to even larger amount of zinc runoff, particularly in the first few years after installation. There has been a bit of research conducted on the subject but I don’t believe it is terribly conclusive. Here are some links and a short blurb on the health risks of zinc that the Hotline has put together:

Studies showing the different contamination levels based on roof types and other rainwater harvesting information.

From "Roofing as a source of nonpoint water pollution" Chang, M McBroom, MW Scott, Beasley R
Austin State Univ.:

The roof runoff was compared to rainwater... Based on 31 storms...
"concentrations of pH, Cu, and Zn in rainwater already exceed the EPA freshwater quality standards even without pollutant inputs from roofs..."

Hopefully this will help to answer a few of the questions. I think it is a topic that is getting more and more research dollars and attention as water shortages become more and more frequent. As a rule Australia is leading the way with rainwater collection in urban areas (they certainly need to with all the severe droughts they are experiencing as of late) so they are usually the ones to watch for newly published results. Again, our policy is better safe than sorry.

I hope that helps. Don't worry too much about it. I'm sure we're breathing in way more pollutants and chemicals living in the city then you are possibly ingesting from your veggies grown with roof rain water.

Miss Notesy said...

I'm with that goofy county doctor's wife, try it out on a pesky dog. :-)

Greenpa said...

Chile- yeah, West Nile virus is something you don't want to ignore. Where I am; one more puddle won't make any difference to the mosquitoes; but in some places, it might. Bear in mind you're never going to get the mosquitoes down to zero; maybe tricking them into feeding the frogs in your barrel would result in fewer adults than if they searched for some puddle with no frogs?

Rae- if you have your own water system, in a place where there's tons of water- I think a rainbarrel is probably not very useful. My own water is pumped by wind (house) or solar electricity (greenhouse) so the burden on the world is small.

If you're in the city; and your water use puts demand on the city system- that's different. Anything you do to cut use is helpful.

It's a complicated world! :-)

Oldnovice said...

"concentrations of pH, Cu, and Zn in rainwater already exceed the EPA freshwater quality standards even without pollutant inputs from roofs..."

So, bottomline: Rain is not fresh water. WhoKnew? LOL.

I'm saving rain water anyway. I live in North Texas and we've had droughts for so many years that the rains we're having currently have turned our patio green. I doubt very much that our asphalt shingles contain something designed to ward off growths common in areas with tons of rain/year. I just got some 5 gallon buckets (with lids) on sale at Home Depot and stick my "regular" buckets outside when it starts raining. 'course those I bring in as soon as the rain's over to discourage the skeeters. I water the inside plants, use the water to clean things, etc.

I don't think the "Little House on the Prairie" people thought about how much zinc might be on the roof shingles or whether the cutting board needs bleaching after cutting the chicken.

Moderation, people. You know it's not potable, but it's probably as safe as the acid rain that didn't fall off your roof. JMO, YMMV.

Kristin said...

open rain barrels = danger for young kids. Ok granted you'll be watching the itty ones, but my 5 yr old LOVES to play in rain barrels. She'll stick sticks in there, etc. I really have to keep an eye on her when we're at friends' houses with open rain barrels.

Rosemarie said...

I don't have any advice on the roof issue, but just wanted to congratulate you on getting a rain barrel. We hooked ours up for the 1st time this spring and so far so good. I don't use it on the vegetables because I have enough plants.

Anonymous said...

As to the contaminates from your typical asphalt shingles, I would NOT advise using rain barrel water for that purpose. I was an Environmental Science major and we studied stormwater runoff and it's effects on watersheds (rivers, streams..etc,). The earlier uses of rain barrels and rain water capturing systems dates back a few 1000 years but the areas that used them were mostly in places like Egypt, Greece, Italy and Middle Eastern Countries. They mostly had clay, brick..etc. roofs. Today, with using different types of metals and composites, it makes it difficult to have clean "rainbarrel water". Even water from copper roofs are not advised for vegatable gardens as well as other metal roofs, cedar shake roofs, and asphalt roofs.

With everything going on in the world in terms of chemicals, plastics...etc., it's just "safer" to use you rain barrel for watering non-edible plants. It has been shown that plants will absorb toxins in the ground and transfer them to the fruit they provide...if they are vegetables or fruit plants. There are certain vegetables that would absorb toxins in larger quantities such as carrots, beets, potatoes...etc because they have direct contact with the soil unlike peppers and tomatoes...etc.

The purpose of a rain barrel or similar systems/devices has changed from providing drinking water/cooking water (early times) to the more modern use of the rain barrel to water flowering plants, shrubs, hanging baskets and the lawn...etc. Many of the rain barrel projects/programs are not even for that purpose. Many conservation districts and watershed offices are using it to less the amount of stormwater runoff that we get in our rivers and streams. It's to help lessen the contaminates that get into our waterways...etc. By using rain barrels, you prevent the runoff from your gutters...drains...that then feed onto driveways or streets which pick up contaminates and then go into stormwater drainage systems.

I wouldn't even advise using it for birdbaths because it would be horrible to know that the birds that you are providing for become diseased or are killed due to your rain barrel water.

All in's just safer to use tap/well water for your vegatable and fruit plants/trees and to use the rain barrel water for everything else in your yard.

Anonymous said...

Wow...I am glad that I read all of the comments, I just set up our first rain barrel which will run off our asphalt shingle roof. I will not use in my herb or vegtable gardens. The bird bath comment got me too. It never ceases to amaze me as to how much I have always just taken for granted. Will continue to try to stay informed...there's alot to know.

Robj98168 said...

I use rain barrels coming off my asphalt roof that I knew has zinc in it. I did not know this, i didn't die as a result of eating last years tomato crop. Good to know. Thanks!

Anonymous said...

I found this bit of info on the OSHA site:

Icarus said...

There are many solutions to the problem of poisons on a roof getting into rainbarrels. First of all use a diverter. What this device does is automatically discard the first 25 gallons or so of the most polluted water that runs off the roof. Most of the poisons and pathogens are in that first flow of water. No need to spend hundreds of dollars on a "commercial diverter" - you can easily make one yourself. Secondly, use a slow sand filter - this you can also build yourself for under 75 dollars. It will take out 99 percent of the bacteria and virus pathogenic organisms. Slow sand filters have been used for over 100 years. On the output of that filter use a carbon granule filter - this can also be built for the cost of some 1 1/2 inch pvc and several fittings and some carbon granule filter material - maybe 25 dollars. There are places that will test the water for you although it is quite expensive if you don't know exactly what you are looking for. I use Amtest in Woodinville. You can google them - they have a website with their prices and tests listed. I have been studying slow sand filters and rain water harvesting since I graduated from the UW in 2006. There are coatings available that you can put on your roof that will prevent the bitumens from the roofing from seeping into your roof runoff. Slow sand filters will remove some of the heavy metals and other metals from your water such as lead from the drain vents, and zinc from the roofing (it is used to kill moss). Metal roofing can be installed over composition roofing or any roofing because it is light. The metal roofing brand name 'Galvalume" is what they use in Texas where lots of people harvest roof water for drinking purposes. This roofing consists of an alloy of zinc and aluminum which is coated by a non-toxic baked on enamel finish I believe it is nsa 61 and awwa 100 approved. There is much more info on my website including instructions on how to put together a diverter, and a slow sand (biosand) filter:

The concentration of chemicals from your roof will depend on its age and whether or not it has built in moss killer (usually zinc). The standard water test for Snohomish county tests for most metals including zinc. After you read the Amtest website you see that the test for Whatcom county is the best test to get. Also bitumens (voc volatile organic compounds) and coal tar are what you would what to check for if you have a composition roof. Most composition roofs have a sand coating that is inert but the coloring used in the sand can have poisons in it. There was a study done in California on the manufacture of roofing and its effect on contamination. I have much more info than I can put in this post - much of it is on my website but the is some that has yet to be added. I have located roofing locally that looks like it will be ok for potable water production (with the use of a diverter and biosand filter of course). Also consider a uv filter and a 10 stage filter - also note most of the runoff from hundreds of thousands of roofs eventually ends up in water and soil around your house - so if you are only watering your garden filtered water from your rain barrels may not be all that bad. What I did was had the water checked pre-filter and post-filter. After looking into this problem for some time, I would not recommend drinking the water from an asphalt or 3-tab, or cedar shake roof under any circumstances for extended periods of time. Watering a vegetable garden may not be that harmful as the concentration of poisons after the filter may not be strong enough to build up in one season. Watering a fruit tree may be another concern however - but consider this if the runoff from your roof drains anywhere near your garden or your fruit trees, the chemicals from your roof that do not biodegrade will be super concentrated in the soil. Have your water checked for the most common contaminants and then for the voc's and coal tar derivatives. You will know then if the water is safe from a chemical point of view. The biological contaminants can be removed using a slow sand filter - they are the least of your worries.

Anonymous said...

Just because zinc didn't kill you yet, doesn't mean it's good for you. Nor is it safe just because the oligarchy says so! Don't even get me started on aluminum.
You are a generation of Americans, who grew up without any science education at all. You don't understand even the most basic processes in anorganic chemistry, let alone organic chemistry and biology. Thinking that choosing to be a 'flake' automatically predisposes you for medically and socially correct decisions is just another result of your upbringing. Rain water won't run through soaker hoses, at least not for long. Come on, even the disolved solids in most treated water are enough to clog a soaker hose within days. So run to save the environment by buying more products. Especially ones made from stuff that has to be torn from deep underground and then tons of pollutants need to be generated before the final product arrives at your organic front door!
Stay with your dayjobs, eat poptarts and shave your armpits. You folks ain't gonna make any difference with you half-assed attempts at goodness...

Dave said...

For what its worth, some info on hydrocarbon pollutants from roof water collected from a "composition" roof. We have been testing a slow sand filter/diverter system here since 2007. See for all the details. The most recent test shows that hydrocarbons are significantly reduced by the diverter, and further reduced by the slow sand filter. It is possible to build a first flush diverter for not much more than the cost of the barrel and some pvc pipe (this is also on the website) Once the first flow of water has been discarded,even in the summer, the remaining water is of much higher quality. There have been quite a number of epa certified tests done on this system. It has become quite clear that in the winter months, water from a rain barrel will likely be ok to water a garden with depending on the type of roofing material used. In the summer months, without using a diverter, the water is very bad. As far as lead from a roof, we have not tested for that yet. For those who do not have a drilled well, make note that in the past, the seal on the screen was lead. I do not know what they are using now.

Dave said...

One thing to keep in mind, edibles from trees and shrubs aren't affected by the water. Any pollutants from water will not travel through the wood into the edibles. This is what I learned from my permaculture class. Roots from things like lettuce or tomatoes are less at risk, the main thing to think about is watering on the lettuce or leafy stuff that you're going to be eating. Personally, I don't worry about it much, but I do plan on replacing my roof with some kind of metal that is safe to drink the water from.