"Can I clean a bird feeder in my dishwasher?"
If you’re asking this question, you’re probably really asking, “Will the dishwasher damage my bird feeder?” What you should be asking is, “Is it safe for me and my family if I clean the bird feeder in the dishwasher?”
I dug into the scientific research for you and guess what?
Science strongly suggests it is not safe to clean your bird feeder in the dishwasher, especially if there is an immune-compromised person in your home.
Reasons not to clean a bird feeder in a dishwasher
- Dishwasher sanitizing cycles are designed to kill mainly food-borne germs.
- Wild bird poop can carry more than 60 diseases, including at least one that can be fatal in humans.
- Dishwasher sanitizing cycles don’t always work effectively, even when NSF-certified.
- The germs from your feeder will end up all over the inside of your dishwasher.
- Germs can transfer from the inside of the dishwasher to your dishes and also escape from the dishwasher into your home.
- Chlorine-based dishwasher detergents can actually make sanitizing LESS effective at sanitizing.
- There is a better way to clean bird feeders: Grapefruit Seed Extract is safer for you and the birds and is up to 100 times more effective than bleach.
What about the sanitize cycle?
Consider this: the majority of dishwashers don’t even get as hot as the recommended safe cooking temperature for chicken (165º F).
Also, the sanitize cycle on a home dishwasher is meant to kill the kind of food germs typically found in a kitchen (not in wild bird poop.)
Finally, sanitization may kill bacteria on the dishes, but recent scientific research shows that dishwashers shelter and grow microbes that cause disease in humans.
Let's look at the science
I read dozens of studies to gather the information here - some of them are listed at the end of this article
Dishwashers always have germs inside
Until 2011, no one in the health field gave a second thought to dishwashers as a potential hazard for human health.
Then a team of scientists decided to swab the rubber seals on 189 domestic dishwashers in a dozen or so countries all over the world.
They found that 62% of the dishwasher seals were contaminated with various fungi, especially two species of black yeast that are known to cause disease in humans.
The fungi were present not just on the rubber seals, but also spread over the entire interiors of the dishwashers.
Dishwasher germs come from items put into the dishwasher
A 2019 study tested dishwashers in 30 homes and found, on average, 4 to 8 kinds of microbes per dishwasher, and a total of 632 different microbes during the study.
The study found that these microbes were not coming from the tap water, but rather from items put into the dishwasher.
Can you imagine the nasty microbes that might be introduced if you were to put a dirty bird feeder in the dishwasher?
Germs can spread from ‘dirty’ items to ‘clean’ items within the dishwasher
A study in 2004, tested a hospital-type dishwasher to see whether soiled dishes could spread microbial contamination to other dishes. Long story short, they could and did.
Again, imagine what could happen if you put a bird feeder in the dishwasher!
Dishwashers don’t always sanitize effectively
A 2013 study evaluated 103 domestic dishwashers with sanitizing cycles that were being used in small health-related establishments such as small establishments, such as family daycare services, group homes, and residential care homes.
They found that 17% of the dishwashers studied did not kill germs effectively enough.
Surprisingly, dishwashers that used chlorine-based detergents were more likely to FAIL this test.
My takeaway from the science is this: if you put a bird feeder in your dishwasher, there’s a strong chance you’ll be exposing yourself and your family to the diseases wild birds can carry.
Better ways to clean your bird feeder
Here's a better way to clean your bird feeders:
1. Always wear rubber gloves and a flu mask to protect yourself.
2. Remove any caked-on crud with a stiff brush and wash the feeder thoroughly with soap and water.
3. Soak the feeder in a 10% bleach solution for an hour or so, rinse well and let it dry before filling OR
4. Consider using Grapefruit Seed Extract (GSE)instead of bleach.
What's so great about Grapefruit Seed Extract?
Grapefruit Seed Extract (GSE) is a very acidic, bitter substance derived from the seeds, membranes, and pulp of grapefruit. It is non-toxic when diluted as directed and fully and quickly biodegradable.
Quite a number of studies have shown that GSE is extremely effective at killing hundreds of bacterial, viral and fungal organisms, as well as a large number of single-cell and multi-celled parasites.
For example, testing done by Bio Research Laboratories in Redmond, WA, USA found that GSE was
“ten to one hundred times more effective than chlorine” against Candida albicans, Staphylococcus aureus, Salmonella typhi, Streptococcus faecium, and E. coli.”
How to use GSE for cleaning bird feeders
First, it’s important to make sure you get a high-quality GSE product that does not contain other disinfectants and does not contain alcohol.
Look for a liquid product that contains only grapefruit seed extract and vegetable glycerin and dilute as follows:
Regular strength GSE: use 60 drops in a 32 oz (950 ml) spray bottle; spray from a distance of one foot (30 cm) or less.
Maximum strength GSE: use 30 drops in a 32 oz (950 ml) spray bottle; spray from a distance of one foot (30 cm) or less. https://amzn.to/2t7xOE9
If you’d rather soak your feeder than spray it, add 40 drops of regular strength GSE or 20 drops of maximum strength GSE per 9 US gallons (18 L) of water and soak for 30 minutes.
Does GSE actually work? The Naysayers.
If you look beyond this article for information on GSE, you’ll probably come across “Not natural, not safe: Grapefruit Seed Extract”, a 2016 article by Scott Gavura.
That article claims there’s no scientific evidence that GSE has any disinfecting properties at all unless the product includes synthetic preservative/disinfectants such as benzalkonium chloride, and that all GSE products contain these disinfectants. That’s just not true.
At least one of the studies I looked at specifically addressed this possibility.
Here’s what it had to say:
“GSE used in this experiment was assayed for its contaminants, and 0.0024% BZC was detected. BZC is an analogue of konium, which is originally present in grapefruit seed.
However, in order to confirm that the BZC content would not contribute to the bactericidal effect of GSE, bactericidal activity of 0.0025% BZC was tested.
… BZC did not show any bactericidal activity in the given contact time. Previous studies reported that GSE, void of any contaminant, can exhibit bactericidal activity, which is consistent with the findings of the current study.”
This study focused on GSE’s effectiveness against certain pathogens carried by birds and was found to be highly effective against all but one (that doesn’t affect humans.)
Heather Dessinger, who writes the Mommypotamus blog, has another article you’ll probably see if you do further research. (Why I Don’t Use Grapefruit Seed Extract.)
In claiming that GSE is ineffective, Dessinger too relies on old research (2001) and also leans heavily on Wikipedia’s article about GSE, which is based on even older research.
All three of these ‘naysayer’ sources are at the very least out of date and don’t reflect current research.
Dishwasher, bleach or GSE?
I hope I’ve convinced you not to put your bird feeder in the dishwasher! As to other cleaning methods, I personally have used bleach up to now with good results.
I’m persuaded that GSE would be an effective disinfectant for bird feeders and will definitely give it a try. (I’d never heard of it until I wrote this article.)
What about you? Would you put a bird feeder in the dishwasher? If not, how do you clean your feeders? Tell me in the comments below
Please share this article with everyone you know that might be tempted to clean their bird feeder in the dishwasher!
Image at top by Daniel Hatton (CC BY-NC-ND 2.0)
Some of the many studies I read when writing this article include:
Zupančič, J., Turk, M., Črnigoj, M. et al. The dishwasher rubber seal acts as a reservoir of bacteria in the home environment. BMC Microbiolology 19, 300 (2019) doi:10.1186/s12866-019-1674-5
Zalar P, Novak M, de Hoog GS, Gunde-Cimerman N. Dishwashers – a man-made ecological niche accommodating human opportunistic fungal pathogens. Fungal Biology. 2011;115:997–1007.
Nicolella C, Casini B, Rossi F, Chericoni A, Pardini G. Thermal sanitizing in a commercial dishwashing machine. Journal of Food Safety. 2011;31:81–90
Ståhl Wernersson E, Johansson E, Håkanson H. Cross-contamination in dishwashers. Journal of Hosp Infection. 2004;56:312–7.
Dru Sahai,Emily PetersonYe Li.Microbiological Assessment of Utensils Cleaned by Domestic Dishwashers in Ontario Small Establishments. Food Protection Trends, Vol 35, No. 3, p.185–195
Diane D. Addi et al. Disinfectant choices in veterinary practices, shelters and households: ABCD guidelines on safe and effective disinfection for feline environments. Journal of Feline Medicine and Surgery, Volume: 17 issue: 7, page(s): 594-605
Beth M. Layton. Disinfectants and Salmonella: A Study Showing the Effectiveness of Disinfectants Against the Bacteria Salmonella. Saint Martin’s University Biology Journal, May 2006, Volume 1
Heggers JP, Cottingham J, Gusman J, Reagor L, McCoy L, Carino E, Cox R, Zhao JG. The effectiveness of processed grapefruit-seed extract as an antibacterial agent: II. Mechanism of action and in vitro toxicity. Journal of Alternative Complementary Medicine. 2002 Jun;8(3):333-40. Erratum in: J Altern Complement Med 2002 Aug;8(4):521. Reagor Lana [corrected to Reagor Lee]. PubMed PMID: 12165191.
Miyuki KOMURA, Mayuko SUZUKI, Natthanan SANGSRIRATANAKUL, Mariko ITO, Satoru TAKAHASHI, Md. Shahin ALAM, Mizuki ONO, Chisato DAIO, Dany SHOHAM, and Kazuaki TAKEHARA. Inhibitory effect of grapefruit seed extract (GSE) on avian pathogens. Journal of Veterinary Medical Science. 2019 Mar; 81(3): 466–472, accessed here January 14, 2020
Cvetnić Z., Vladimir-Knezević S. 2004. Antimicrobial activity of grapefruit seed and pulp ethanolic extract. Acta Pharm. 54: 243–250. Accessed here on January 14, 2020 (This link will download the PDF file.)
Information about Grapefruit Seed Extract (GSE) AT30 Diphenol hydroxybenzene complex, accessed January 14, 2020
G. Ionescu, R. Kiehl, F. Wichmann-Kunz, Ch. Williams, L. Ba S. Levine. Oral Citrus Seed Extract in Atopic Eczema:In Vitro and In Vivo Studies on Intestinal Microflor, Journal of Orthomolecular Medicine, Vol 5 No 3 1990
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