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Drainage channel

I have been getting a lot of stick from beekeepers here in the UK about the drainage channel in the Flow system. They are saying it is a source of possible infection as the bees can’t get in it to clean it. That there is bound to be traces of honey left in there…exposed to the air…becoming hydrated…so pathogens could grow in it. So that when you next drain honey through it…the honey could become infected too.
Can you give your stance on this and what you think about whether the channel needs cleaning between harvesting and at the end of the season. Has any testing been done? Swabs taken etc? Thank you

Some day I am going to have to do an experiment. Take a small sample of honey and leave it open at room temperature, and a comparison sample in the hive, but with a way to keep bees out. Then every week, take a sample and test with my refractometer.

I don’t think swabs and cultures would really help, as the culture medium is not a true reflection of what is happening in the honey. If I was going to set up a test for this, I would take a sample and make a smear on a microscope slide, staining it for yeast, bacteria and bacterial spores (C. botulinum etc). Might need to do it by taking a known volume of honey, diluting it, spinning the bugs down, then smearing the spun pellet onto a slide. It would be tedious, but if people are really worried, it might give an answer.

Having gone so far down this road, I now need to back track a little. I think bacteria are not very good at growing in hyperosmolar solutions (even under-ripe or diluted honey). Yeasts are much better at it. However, very few yeasts are pathogens, so even if they did multiply in the honey remnant, I can’t think that it would be toxic or “infected”, just slightly alcoholic.

I didn’t get a Flow harvest this year, but I think I will probably rinse the frames in lukewarm water, in particular flushing the channel. The bees should take care of the cells next season - they won’t store (or add to) fermenting honey.


it would be good to hear from Flow on this subject.


From the Flow Team FAQs

Does the honey in the bottom of the Flow™ frames ever go mouldy, ferment or crystallize? If so, what can I do about it?
In: Frequently Asked Questions Viewed: 7,986 times

We recommend cleaning Flow™ Frames at the end of the summer, after harvesting is finished for the year.
This is easy to do without removing the frames from the super or the super from the hive. You can squirt water into the trough and then let it drain out.
If there are still signs of dirt, mould or crystalised honey, you can use a bottle brush to loosen it and then wash out with warm water.


The questions directed at me were about botulism and similar pathogens. Would 50% hydration keep them under control?
If the answer is to wash out the channel with dilute Milton or similar…that’s fine.
I don’t think mould, fermenting honey or crystallised honey is a particular worry as you can easily wash them away.

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I don’t know that they’re being picked on? But the only sources in reference to this being raised as an ‘issue’, that I’ve come across is on this forum. From the little information I’ve looked at in further research into to this, I don’t feel like it’s really an issue & perhaps is more a result of over zealous cultures of cleanliness? The current recommendations for kids regarding allergies is higher exposure to allergens. (I realise that they are not talking about allergens re the Flow frames.)
I suppose I’m more interested in, is it something that occurs with the honey in these conditions, to what degree, the how & why & is it something they had to think about or research (I don’t imagine it would, or should have been)…curiosity.

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Here is another thread with questions around this…



Well I was hoping for a reply from Flow too. Perhaps they don’t know? In which case they should say so.


This is one I was referring to, maybe we should link the threads @Faroe

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Hi Dee I agree it would be nice if flow could answer this question and put peoples mind at rest. It would also stop others from making assumption’s on there behalf.

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Hi all,

Guessing the Good Ole Boys n maybe a lady or two just need something to bitch about without any data or truth…

Who knows ! Maybe it’s true but I’d just say, “Put up or Shut up”. I guess I’m just getting old n don’t really give a care unless there is truth n data … Speculation gets nobody anywhere except on a SWEAT for nothing.

Shoot … If your not careful … N use your kitchen it is possible to have a bit of contamination in that HONEY as well. Tell them to get a LIFE … Those old goats will go down “ten toes up” still giving their undocumented B.S.

Wow ! How did I ever get on this War Path :sunglasses:. !! Sorry folks. But those rejects need something else to get under their saddle n move on!

Ta ta n Cherio á Gram use to say,


P.s. Hey Doc @ Dawn. You going lay out a set of those peatree dishes for that experiment !? :sunglasses::honeybee:

. Do I need one of those honey moisture meters, thermometer n what else. Need to get this fun experiment on the road ! :sunglasses::wink::+1:

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Just how do we figure out if any of that bad stuff exists in thar reseses ?

. Don’t see any critters ! :space_invader::ghost::japanese_ogre::rat::ant::beetle::snail::paw_prints: in there :smile::+1:. Am I BAD yet ! Gerald.


Wow, I didn’t realize there was that much nastiness trapped in those channels. Great shots Gerald!

Botulinum isnt an issue in the flow hive drainage channel. Even if the moisture content in the channel is high enough to allow bacterial growth… oxygen inhibits botulinum. It requires low oxygen levels.

So spores may be present but no more than any other honey for sale.

There could be other bacteria out there to talk about but we needn’t concern ourselves with Clostridium botulinum.

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The black specs looks like rodent feces :worried:

The other flaw in this criticism is that the honey will absorb water. Honey is hygroscopic but only if the air is sufficiently humid.

Honeys tend to be in equilibrium with humidities between 55-65%.65% humidity is roughly in equilibrium with 22% moisture honey.

I found a reference that states that, based on a wide range of literature, at humidities <=61% there is no microbial growth in honey.

A another way of putting it is… the air in the hive is sufficiently dry for the bees to be able to evaporate water off the honey most of the time - otherwise it would be impossible for the bees to make honey. Honey residue in the drainage channel will be in equilibrium with the air in the hive and so during the honey production season the conditions for dilution of the honey won’t exist.

This doesn’t address outside of the honey season. It is possible that for periods of the year (such as cold weather or tropical weather) the humidity in the hive could be higher than 61%, meaning that sufficient dilution could lead to microbial growth. But dilution to 50% water content would take close to 100% humidity. An earlier reference in this discussion quoted research that found pathogenic bacteria couldn’t grow in 50% water content but that non-pathogenic organisms could.

Based on this, I am convinced that during honey production there is no risk of bacterial growth and that outside of that period there is no risk of pathogenic bacterial growth.

If there is any non-pathogenic bacterial growth over winter, it will be killed off within a few days of being mixed into the first honey harvest.

All in all, I would argue that the risks of contamination are in the bottling process (common to traditional and flow harvesting methods) and not in the flow hive.


This is a list of bacteria that can grow in foods at different “water activities”.


“water activity” is the humidity that the material is in equilibrium with. I.e. honey with a water activity of 0.6 would be in equilibrium with 60% humidity (i.e. in 60% humidity air, it would neither gain nor lose water).

Pure water has an activity of 1.

Note that bacteria won’t grow in the residue until you hit a consistent humidity in the hive of 86% and 97% for C. botulinum.


Nice to see that they agree with my original comment:

I have to admit, that in my mind I lump yeasts in with fungi. That is a bit approximate, but they tend to behave similarly. Thank you very much for finding the literature reference to clarify and back me up, @Dunc! Nice work. :blush:

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Thanks Dunc! This is the information we needed. I had forgotten that C. botulinum is an anaerobe. This coupled with your other information makes botulism poisoning from this mechanism in someone less than a year old improbable. If you still have the references handy do you mind throwing them the bottom of the post? I think this could be a very quotable post when this issue is brought up.

I’ll dig out the key references. The key one is the last one that I posted.

However, the less than a year old thing is still a risk. All honey (including heat treated) can contain botulinum spores (just not the live bacteria). For kids under a year, their gut can’t stop the botulinum growing and so it grows there and produces the toxin. From what I’ve read, it’s pretty rare that a child is admitted for botulism from honey but it is possible and potentially lethal, hence the advice not to give them honey. But the risk from raw flow hive honey is no higher than heat treated shop bought honey. I didn’t give honey to my babies and would recommend that others don’t either.

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