In some homes, it is believed that static electricity can lead to inferior grinding, and that has coffee connoisseurs searching for answers.

Will water help, or is it just making a mess because while a little may help, people will use too much? 

Coffee is prone to fads the way athletics - nasal strips, cryo-therapy, those weird blue-light filter glasses - and certainly nutrition is. A study may create a correlation and people sell a produce. Giving coffee acupuncture before tamping in espresso was all the rage starting in 2020 and for the last year some have sworn by adding water to reduce static electricity.

Is it just finding a way to make beans 'oilier', and possible reducing grinding efficacy, or a real thing?  University of Oregon Professor Christopher Hendon and colleagues say the benefit goes beyond physics - it can help flavor.

Is it a meaningful effect?(1) The effect of a fly flapping its wings effects the moon, we can detect it, but that doesn't make it meaningful, any more than nearly 100 percent of endocrine disruption claims are anything except belief in homeopathy bolstered by a detection at molecular levels. The authors believe that their volcanology is sound and even note that volcanoes and coffee grinding have things in common - except not hot ash and poisonous gas.

The "Ross droplet technique" is adding a bit of water to the hopper before grinding and is attributed to David Ross in 2005 - but it was a newsgroup Alt.Coffee post, not a journal.(2)

The authors say this coffee version of 'folk medicine' has merit. They contend water does reduce static electricity in coffee the way it does in wood pulping. But then some in the amateur community claimed it led to better taste also. The daisy chain of beliefs contends that less static electricity will mean less clumping also. Espresso enthusiasts are obsessed with clumping, they even argue about the shape of the layout of the acupuncture needles they stick into their grinds.

They used a Faraday cup to measure the electrical charge of coffee particles and found that moisture mattered. Darker roasts have more oil, that makes grinder enthusiasts crazy, and less moisture, but also a negative charge. Light roasts had more moisture and more positive charge. So adding a drop of water before grinding removed the static charge and reduced clumping which, and and it okay to be skeptical here, got them 10 percent more yield from the coffee. They believe that baristas will save a lot of money whereas actual shop owners will want to see what sort of cheap blade grinder was involved if they had 10 percent retention in any case. 

Prof. Christopher H. Hendon. When a coffee cup is in your university bio pic, you mean business.

It could be a minor effect, static is real and they measured the internal moisture and charge, but like the beating wings of a fly and its effect on the moon, how important it is becomes a matter of taste.

If you are prone to buying pearl-handled acupuncture needles and swear that means better coffee(3), a drop of water may help, but real experts are using +/-1 18 grams of beans, so if adding a drop of water and its .05 grams has a real effect on clumping, it absolutely has an effect on taste. 


(1) The same school has work claiming it knows why Taylor Swift is successful, so academics are not immune to embracing culture to get media attention.

(2) That's not even good enough to be gray literature used by the IPCC to claim the Himalayas will be melted away by 2035, which was at least speculation in a 1999 magazine claim the IPCC decided needed no fact-checking before including it in their official report and that set off the 2010 "ClimateGate" scandal. 

(3) You never know. Taste buds vary by over an order of magnitude in humans, and one of my favorite guitarists from the 1980s, Eric Johnson, could hear the impact of different battery brands in his effects box.