Honey Water Content – Is it Too Much?

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Bees make honey from plant nectar. It contains sugars, proteins, enzymes, pollen, organic acids and many other substances – including water. But, if the honey water content is too high, it will spoil or ferment. Beekeepers can use a honey refractometer to measure the moisture content of their crop.   

Percentage of Water in Honey

Honey refractometer used to measure content of water in honey image.

The percentage of water in honey varies depending on the nectar source and environmental factors. Some types of honey tend to have a higher moisture content (or lower) right out of the hive.

The goal is to have honey that is between 15.5 and 18.5% water content. If too low in moisture, it may crystallize faster.  However, high levels of water leads to fermentation. 

Honey is hygroscopic. This means that it absorbs moisture from the air. Frames or boxes that are harvested before the bees have finished the conversion process-may be too high in water.

Also, improperly stored frames (even capped comb) can absorb moisture from the air before extraction. The same can occur when liquid is stored in open buckets without tight sealing lids.

No one wants a ruined crop. And for beekeepers who sell honey, having your product at the correct moisture level is very important. In the United States, this product is evaluated on a grading scale. To qualify for Grade A or B, the water content must be below 18.6%.


Any raw food product, can contain contain some natural yeasts. When yeasts, warm temperatures and water combine – you get fermentation. This is a great thing if you are making mead – but not otherwise.

Ripe honey (of a suitable moisture content) contains fewer yeasts. These yeasts can be killed with heat. However, this is not advised as you also destroy some of the good healthy benefits of having raw honey.

What is a Honey Refractometer?

A refractometer is a device used by beekeepers to measure honey’s water content. A tube-like instrument that measures the degree to which light is bent as it passes through material. This is the refractive index.

As light moves though any substance, it changes direction or bends. This is called refraction and the amount of refraction depends on the amount of solids in the solution.

In fact, the refractive index of honey will change a bit due to the solids in it. This is why a range is necessary instead of a set desired percentage.

Refractors come in many different types and are used in industries including brewing, medicine, gemology and the car industry. 

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Honey refractometers are a bit different than other types. Instead of measuring the solids in a substance, they measure water content. This makes them the perfect tool for measuring the level of water in honey.

A regular refractometer can be used to measure moisture too. But those marked for honey are easier to read and understand for the average beekeeper. 

Their scale usually shows between 10-30% water. When measuring sugars (and honey is sugar) the Brix scale is used to get a reading. A reading of 18 degrees brix means the honey is 18% water.

Using pipete to place honey on refractometer prism image.

How to Use a Honey Refractometer

A honey refractometer is easy to use and provides important information about the status of your crop. Any time you have doubts, it is time to test the moisture levels. Begin at room temperature.

  • Pull up the clear flat panel on top of the glass prism
  • Add a couple of drops of honey on the glass surface – avoid bubbles – don’t put too much honey
  • Close the flat panel against the glass and wiggle slightly to spread honey out
  • Hold refractometer toward a bright light – look through the eyepiece
  • Look for the sharp line between the blue and white field – this is your reading
Degrees brix reading of 18% on honey refractometer image.

After use, be sure to clean your refractometer. Use a damp lint free cloth to clean both panels of the unit. Store your tool in the box to protect the prism and other delicate parts.

While there is no universally agreed standard, most beekeepers want the moisture content of honey be between 16-18% – certainly never above 19%. Once the water levels rise about this number, yeast multiplication increases greatly.

Calibrating Your Refractometer

When your refractometer arrives, it is a good idea to calibrate it before using it for the first time.  After that, recalibration once a season helps insure it is working properly.

A small screw on the unit is used to adjust calibration and it can easily get bumped in shipping.  Most new units come with a special reference solution to use for calibration. Follow the instructions that come with your model.

For instance, if the solution that comes with your unit is supposed to have a Brix reading of 20% – you turn the screw until you get that reading.

Using Olive Oil to Calibrate

If you are lacking special solution for calibration, you can use extra virgin olive oil. It will have a Brix reading of about 71.5 – which is 27% water. 

Life the clear panel on the top of the unit, clean the flat glass surface with a lint free cloth. Be careful, don’t scratch it – this is your prism.

Add a couple of drops of your calibration solution to the flat glass – avoid air bubbles. Gently press down the clear panel causing the solution to spread out.

Hold the refractometer towards a bright light, adjust the angle if needed -look through the eyepiece.  You may have to adjust your eyepiece if the view is fuzzy. Look for a blue and white field with a sharp line where the two colors meet.  This is your Brix reading in degrees – i.e. 27%.

If the reading is not very close to that of your calibration solution, you must adjust your refractometer. 

The calibration screw is on the handle and often has a cover. Pop off the cover and use a small screwdriver to adjust the sharp line to the proper measurement for your solution.

Once your unit is reading the olive oil correctly, we know it should be ready use. Remember, you only have to do this process once in a while. It does not require adjustment before every use.

Beekeeper using refractometer to measure honey water content.

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Buying a Honey Refractometer

When shopping for a honey refractometer, there is no need to spend hundreds of dollars. There are plenty of models available for under $50 – many for under $30.

For the everyday beekeeper, these will work just fine. Mine cost under $25 at the time and has been working great for over 5 years.

If you want to pay the price for an expensive digital one, that’s great. However, the lower cost models get the job done just as well.

Remove Excess Moisture in Honey

After breaking down sucrose into two simple sugars, bees use their wings to fan honey down to a stable level of moisture. It is then capped with wax. Therefore, capped frames usually have a low moisture content and pose no problem.

However, that is not always the case. I have had years when a lot of rainy weather and humid days resulted in capped frames with a higher water content than is desirable.

Also, it is common when harvesting honey to have frames that have some uncapped cells on the frame. What is a beekeeper to do to remove excess moisture in honey?

Honey refractometer on frame with uncapped cells.

Reduce High Moisture Content in Honey Supers

If your honey refractometer shows a high moisture level prior to extraction, do not panic. The easiest thing to do is to put the supers in a room with low humidity and have a fan blowing on them for a couple of days.

Most beekeepers keep a room dehumidifier just for this purpose. They are not very expensive and last for years. 

When I have supers that are on the borderline for water content, I sit them on end with a fan blowing through them in my honey room. The dehumidifier is set on 35-40% for a day or two. By then, the honey’s water content has dropped enough to proceed.

Reducing moisture in honey using dehumidifier and fan in room image.

This same process will work for buckets too. You must remove the lid and it is good to have a fan blowing across the top of the open bucket. 

Be advised that having the dehumidifier (or air conditioner) running to reduce room humidity is crucial to the process. A fan blowing humid air will only make the situation worse not better.

Our colonies work very hard to produce a perfect food source. They even make enough to share with us.

Ripe honey lasts virtually forever without going bad. The acid levels and low pH helps prevent spoilage. Stored properly and protected from moisture, it will be ready when you need it.