Become a Creator today!Start creating today - Share your story with the world!
Start for free
00:00:00
00:00:01
Rainwater Catchment & Produce Safety
6 Playsin 2 days
This episode features Nick Panicola, a Produce Safety Technician for the Grand Traverse Conservation District, and Dr. Kevin Tarwa, a recent University of Maryland doctoral graduate. They discuss Dr. Tarwa’s research on harvested rainwater and what it means for produce safety.
Recommended
Transcript
Introduction to Produce Safety and the FSMA
00:00:00
Speaker
Hello and welcome to the Agri-Food Safety Produce Bites podcast, where we discuss all things produce safety and dive into the rules and regulations surrounding the Food Safety Modernization Act Produce Safety Rule.
00:00:13
Speaker
My name
Sanitizer Treatments in Agriculture
00:00:14
Speaker
is Dr. Kevin Tarawa. Recently just defended my dissertation at the University of Maryland. I was working on my dissertation project with look which looked at different sanitizer treatments and how they impacted microbial communities associated with agricultural water and fresh produce. So a lot of my research was on the fresh produce safety side and also looking at various sanitizer treatments. Specifically on the pre-harvest side, we worked with sanitizer treatments for harvested rainwater.
00:00:44
Speaker
and My name is Nick Panicol. I'm a Produce Safety Technician with the Grand Traverse Conservation District. I help provide education and resources for the implementation of the Produce Safety Rule for local farms here in Michigan.
00:00:56
Speaker
Kevin, I'm
Rainwater as an Irrigation Solution
00:00:57
Speaker
glad that we have this opportunity to talk here. We're going to talk about the safety of rainwater collection and its use in growing produce. Do you agree with the statement that rainwater can be safely utilized to irrigate produce?
00:01:11
Speaker
Definitely. um Rainwater overall, it it serves as as an alternative water source and it's cost effective. Not a lot of farmers have access to agricultural water sources. So I think it's it's just very cost effective. And why not utilize what Mother Nature has provided us, you know?
00:01:30
Speaker
I started
Safety Concerns of Collected Rainwater
00:01:31
Speaker
collecting rainwater two years ago. i had a a roof that was washing off into my garden and kind of destroying one of our garden beds. And I thought, why don't i put up a little gutter?
00:01:43
Speaker
put a rain barrel out there and I'll collect the water and I'll use it in the garden. And I was using it all last year, willy nilly, kind of throwing it where I wanted to. And the garden plants love it.
00:01:54
Speaker
You know, i think that's what they really enjoy is they love that rainwater and it's a really easy source of water. And I always feel good about it. And I take my watering can over there. But, you know, my thought process was, well, it's rainwater. It's from the sky.
00:02:08
Speaker
you know There's nothing going on up there that's really too much of a problem, hopefully. So is it is it safe to assume, Kevin, that rainwater collection is just safe in itself? Overall, all I would say in general, ah rainwater that's deposited through the air is generally safe.
00:02:25
Speaker
I would say more of the concern comes with the actual collection of the rainwater, right? Especially when when you when you think of some of the risks associated with other agricultural water sources like surface water and even groundwater in a sense. with surface water generally has higher risk because that of that high exposure. So I would say looking at just collecting rainwater with an open barrel, it's it's almost very similar where you're you're still exposing it to the environment. So I would definitely say a lot of factors like
00:02:56
Speaker
how open your barrel is, as well as even some of the quality of like your roofing material. I think a lot of those factors on how you collect it make a big difference on the quality. Yeah, I think ah you you highlighted a good point. You should consider rainwater as surface water. Yeah.
00:03:13
Speaker
We're talking about contaminants here. um So what are some types of contaminants and where are they coming from? In terms of microbial contaminants like E. coli, salmonella, or even listeria, I think a lot of that comes from what is deposited onto your roofing material. So for instance, wildlife and small little rodents that might be crawling on top of your roofs might may deposit some fecal matter in there where during heavy rainfall periods, that's potential animal fecal matter can deposit it into your rainwater system. As as
Contamination Risks in Urban vs. Rural Areas
00:03:49
Speaker
well as we've we've looked at various studies that
00:03:52
Speaker
have highlighted different the the risks associated with different roofing materials, especially ones that may leach certain heavy metals. And depending on a lot of the areas as well, where there's high pollution areas, that ah that rainwater that's deposited from the air can also carry some of those pollutants, heavy metals that might potentially trickle into your rainwater system, as well as ah even like physical contaminants. Even from a consumer standpoint, it's always recommended to clean out your gutters. So looking at some of those risks, I think is really important to assess your quality of your rainwater.
00:04:31
Speaker
You brought up pollutants from the air. Where are those coming from? And are we seeing those as a heavy concern when collecting rainwater?
00:04:43
Speaker
Overall, looking at cities compared to more rural areas, you'll definitely see more traces of pollutants such as like heavy metals that might be in the air. And and and that's mainly due to more more of like a human ah behaviors in a sense where we have more...
00:05:02
Speaker
city traffic, things like that, causing more risks of pollutants in the air. We talk a lot about potentially harmful like and ah like nitrates and fluorides that might be in the air due to increased industrialization, as well as even agricultural production. i
Advantages of Rainwater Collection
00:05:19
Speaker
don't want to say in rural areas, it'ss there's no detection of some of these contaminants, but I think just with the rapid increase in population, as well as you know industrialization and businesses just booming, I think
00:05:34
Speaker
cities overall have a higher risk compared to more rural areas as well. So that it's it's more kind of human human-made pollution, I would say, in a sense. But yeah, I would say that's where a good majority of that pollution comes from.
00:05:51
Speaker
So taking these contamination risks into consideration, why are people collecting rainwater at all? Why aren't they just relying on municipal sources or you know out of their tap or ground out of the groundwater through a well?
00:06:05
Speaker
In terms of just collection over um collecting overall, I think it's just very easy. um And i would say also also cheap as well. I think a majority of our are our water that we have on Earth is used mainly for agriculture production. and I think in terms of um why we even use rainwater in a sense, I think it's just very easy. And especially with some of these areas that are don't have as much access to waters, and as well as even areas where we we see a lot of malnutrition. I think harvesting rainwater ah is is it's just has just been very common, has been used even as far back as
00:06:51
Speaker
4000 BC for agricultural production. Looking at sustainability as um nowadays, I think that's that's kind of one of the main drivers in terms of looking at agriculture from more of a sustainable and efficient standpoint.
00:07:07
Speaker
Can we talk a little bit
Storage and Quality of Rainwater
00:07:08
Speaker
about collecting now for later use? What would maybe be some concerns for doing that? If you are going to store your rainwater, just making sure that you clean out your rainwater, like clean out your barrels, minimize potential biofilms that might develop nutrients that might enhance some of the growth of some of these bacteria.
00:07:29
Speaker
um and and And in terms of even looking at what temperatures your water is stored at. So I think a lot of people may just store their waters outdoors. And in the summer months, you know we have a lot of these warm temperatures that bacteria love.
00:07:43
Speaker
So I think um looking at some of those factors makes a huge difference in terms of the the quality of your stored rainwater overall. As we're harvesting this rainwater, what are some ways that we can ensure its safety?
00:07:58
Speaker
We've seen a lot of cases in in in studies where they've applied certain filters. First flush diverters, especially if you're um collecting your rainwater from a like a gutter off of a roof. i think So with that first flush diverter, you're essentially creating this diversion in terms of when we have these precipitation events where whatever material that's on your roofing units, once it starts to rain, that first...
00:08:26
Speaker
a kind of wave of water that's depositing into your barrel will enter this first flush diverter. Almost acts like as a natural filter in a sense where any debris, any foreign materials will leach into this first flush diverter, which will settle at the bottom. And then once the water raises to a certain level,
00:08:49
Speaker
it'll then enter into your actual collection water system. So various studies have shown that this is very effective. Even implementing like a like a mesh filter as well to prevent any um leaf debris or foreign materials from entering a rainwater barrel is also very effective.
00:09:10
Speaker
and and And also just looking at just natural UV treatments. um You know, studies have shown that UV treatment is effective at killing bacteria, but it all depends on, i guess, the...
00:09:25
Speaker
ah the material of the barrel that you're using and whether that UV lights is able to even penetrate um and and penetrate that that barrel and and and be effective. So looking at those sort of factors is important as well. So a lot of different um treatment options. and and And I would say in general, they're very, very cost effective as well.
00:09:50
Speaker
I guess I wanted to talk a little bit about filters. You know, you talked about a mesh filter. That sounds like a thing
Purifying Rainwater: Filters and Treatments
00:09:57
Speaker
that somebody can implement at home. I've heard about sand filters. I've also heard about ZVI sand filters. What is ZVI and how does it work?
00:10:08
Speaker
Yeah, so ah ZVI is short for zero valent iron filters. and the way that it works, it's it's it's very similar to a sand filtration system.
00:10:19
Speaker
What it does is it's it's pretty much a a system where it has a pump. So you would actually have to implement the ZVI filter in a sense where you have...
00:10:32
Speaker
your rainwater that is collected. So what we did in one of our projects is we collected rainwater in these IBC totes, at least 100 gallons of collected rainwater, where we had an actual ah pump that pumped the rainwater through the sand filtration system. And what it does is the sand filtration system it ah It definitely relies on the flow rates of your system in terms of how fast water is pumped through the sand filtration system. So the sand filtration system essentially can trap any foreign materials, even bacteria, because it's very...
00:11:19
Speaker
porous in a sense, where it's it has a lot of these pores that are around the same surface area as light bacteria, even viruses. And it can also capture some of these like potential heavy metals that might contaminate your harvested rainwater system.
00:11:36
Speaker
So it sounds like the the filters act as like a physical removal process. Yes. While like ah a first flush diverter is excluding kind of that first and maybe most contaminated bit of water that could get into your system.
00:11:51
Speaker
And then we talk about treatment of water, which I think we're going to talk about next in the question. We're talking about like a chemical kill step. So, you know, removing, is it killing those bacteria or is it preventing their growth? What does that look like?
00:12:03
Speaker
In terms of chemical treatments, we've used parasitic acid, ah very commercially available. We used a PAA from a biosafe system. So Sanidate was the one that we mainly used for pre-harvest agricultural treatment.
00:12:20
Speaker
PAA is very effective. It has a much broader kill spectrum compared to something like chlorine-based, which chlorine is very Effective as well. However, you have to factor in things like the pH because chlorine is very effective at a very narrow pH range compared to parasitic acid.
00:12:44
Speaker
So yeah, we've seen that it was very effective and we only used 8 ppm, which is very low compared to even commercial produce washing, which generally goes between about 50 to 80 ppm. So we saw very effective results in terms of reducing foodborne pathogen levels.
00:13:02
Speaker
um But then we've also seen things we looked at just sort of the natural um microbial community that is present in rainwater. And and we saw we saw varying results there um because a lot of these natural microbes are Environmental pathogens that have been adapted to some harsh environments may have developed things like stress stress resistance with even various different treatments. However, in terms of looking at some of the main concerns with fresh produce, we saw that it was very effective at reducing specifically foodborne pathogens.
00:13:42
Speaker
And when you talk about chlorine products, i said how is household bleach and ah a usable option there? Yeah, in terms of ah household bleach, so yeah, we worked with sodium hypochlorite, which essentially is just household bleach.
00:13:56
Speaker
um The reason why we didn't want to ah use chlorine as a treatment was because...
00:14:07
Speaker
During the project we worked on, i would say we were treating rainwater once per week. um And again, looking at some of the risks associated with chlorine is, you know, ah looking in terms of pH, right? so in industrial settings, especially during like post-harvest washing, a lot of these operations have um dosing strategies with their chlorine systems where it constantly monitors hers the pH, constantly adds more chlorine as the chlorine levels start to deplete.
00:14:43
Speaker
And then in terms of looking at some of the risks, I would say chlorine in general has a much higher risk just because it can break down into your more toxic byproducts where looking at parasitic acid, it generally just breaks down into three components. So it breaks down into water, breaks down into oxygen, and it breaks down, it breaks down into water, vinegar,
00:15:08
Speaker
and oxygen. So all those three components are very very low risk, especially with vinegar. We always use vinegar at our at home, during cooking. So I would just say in terms of the chemical differences between chlorine and parasitic acid, parasitic acid was just more, in terms of a safety standpoint, i would say it's it's it's much safer as a treatment compared to chlorine.
00:15:36
Speaker
So it sounds like if someone has access to PAA, especially a small grower setting, that's a really good option for treating their harvested rainwater. um And I know something with bleaches as, especially with chlorine and its effectiveness, as the water gets more turbid, it becomes less effective, right? And that's something that may be paired with a first flush diverter might be more useful. And especially if that's all someone has access to, especially if you're ah a gardener or a home grower like myself, But definitely it sounds like PAA is a good good option.
00:16:09
Speaker
Yeah, i've definitely I would definitely say so. Just in terms of, yeah, going back to that first flush diverter. so We've seen a lot of cases. I've worked a lot with both of these sanitizers. and going back to sort of the chemistry with these sanitizers, they're very ah they're both very considered very oxidative. So they're able to react with things like organic matter that might build up in in in in your um your collection barrel system. So a lot of that organic matter can come from...
00:16:45
Speaker
sedimentation can come from leaf debris foreign materials that essentially can increase your organic matter load in your systems and we have seen studies that have shown that when we do see some of these high organic load conditions, these sanitizers can react rapidly with them. Specifically with chlorine, I'd say with parasitic acid, it's much more of a slower reaction just because they both behave very differently in in water. so and And one of the issues too with ah chlorine is that um these high organic matter conditions can...
00:17:28
Speaker
potentially cause chlorine to break down into some of these toxic gases. And
Enhancing Rainwater Safety Practices
00:17:33
Speaker
it's just mainly due to the chemistry where PAA again, parasitic acid it again, just breaks down into those non-toxic byproducts, which don't really create some of these toxic gases compared to chlorine.
00:17:46
Speaker
So I think implementing that first flush diverter or even a filter where you can um mitigate some of the issues that like leaf debris form materials. I think those are very effective in terms of even looking at like a two-step treatment where um you're preventing some of these ah organic matter entering into your wash, um into your rainwater barrel, ah thus maximizing sort of the effectiveness of your sanitizer treatment.
00:18:17
Speaker
I think ah to to add on to that, and I think it's important as the produce safety technician to talk a little bit about how we can utiliz use water, rainwater effectively and safely, even after some of these extra steps. We're talking about layering here, right? We're talking about Implementing a first flush diverter, maybe implementing a treatment system, but I think another layer to that as well as when we're always talking about the utilization of water for crops, we're talking about source and method are normally the two things that i have in my brain. And right now, if we're talking about source, we're talking about harvested rainwater, which we're considering as surface water. So we want to probably avoid contact with the plant as much as possible.
00:19:01
Speaker
um So carefully watering is probably a first one, making sure that the water that we use that comes out of a rain barrel isn't touching the harvestable portion of the crop. implementing maybe if possible some systems like drip irrigation, or maybe we'll talk a little bit about subsurface irrigation. but then there's also methods for if you're going to harvest produce from your farm, or going harvest it from your garden. you probably don't want to wash that produce right away. You can wash it, uh, right before you're about to use it. Um, so if there's anything that's on that produce that there's no water getting into that system that allows those pathogens to grow. Um, and always, uh, at the end of the day, if you cook your food, that's also very helpful too, but we're talking about produce, so we're eating it raw. So that's, uh, but we did also talk about maintaining the system. So, you know, uh,
00:19:50
Speaker
Making sure we and inspect the integrity of our rain barrels, making sure that there is, you know, if you have a little mesh filter on the top and you're seeing a lot of animal activity on there, then maybe that's something that you shouldn't consider.
00:20:02
Speaker
Cleaning your
Rainwater Research and Resources
00:20:03
Speaker
barrel least once a year and rotating the water. You know, we talked a little bit about collecting water, And then saving it for later. It does help also, it seems to use the water that's in the barrel and rotate it frequently. So there isn't maybe that extended amount of time that pathogens can grow in that system.
00:20:22
Speaker
Well, I think this has been such a ah wonderful conversation. and I think it seems that... As we continue down this path of inconsistent water patterns and and people implementing water collection systems for their own use or for commercial uses, this research is just going to more and more important. so um from somebody in the produce safety world that extend my and our gratitude for all this continued great research into how we can do things more safely.
00:20:55
Speaker
Again, I thank you for having me on the podcast. as We picked a good time since this was just fresh on my mind for my defense last week. So I really appreciate the opportunity for you guys to be here.
00:21:07
Speaker
Links to anything referenced in this episode can be found in the podcast description. For more produce safety resources, tools, and upcoming trainings, visit the MSU Agri-Food Safety website at gaps.msu.edu.
00:21:21
Speaker
That's G-A-P-S dot M-S-U dot E-D-U. We hope today's episode helped you take another step towards safer produce.