A Tale of Two Hoses

It was the best of times, it was the worst of times. It was a nice day in the garden, but when you go to disconnect the hose, it is somehow stuck to the spigot, connector, or other hose. You go and get the pliers, but the hose just doesn’t budge. If this has happened to you, then you now know of the chemical reaction that can occur between aluminum and brass hose fittings. Hopefully, this is just two hoses stuck together, and you can cut them off and replace them with new ends. If the hose is connected to the spigot and won’t budge, you may want to contact a plumber before you create a bigger problem.

While knowing the name of this chemical reaction, galvanic corrosion, doesn’t help you while you curse these hose fittings, it is yet another scientific discovery in the garden. Galvanic corrosion occurs when two dissimilar metals are in electrical contact with each other in the presence of an electrolyte. The metals must be dissimilar in their electrochemical voltage. I know, you just want to disconnect hoses, not learn physics, but this stuff is interesting! Basically, aluminum is pretty reactive, especially when joined up with brass, bronze, copper, and even stainless steel. In the case of our hoses, the water acts as an electrolyte thanks to the calcium present in our delicious and abundant limestone aquifer groundwater. You put all these together and, bazinga, you have the aluminum hose end corroded into your brass hose end so strongly that no pliers will ever unlock them.

So, what do you do to prevent this? The easiest way to prevent galvanic corrosion from ruining your nice day in the garden is to only purchase products with the same material as your spigots. Brass spigots, hose bibs, and hose ends have been the industry standard, while aluminum hose endings seem to be more of a recent occurrence. Aluminum is cheaper, so you can understand why the hose companies would be interested in switching. If you already have two different materials, first check and see if you can get them disconnected. If not, start purchasing new hoses that match the spigot and/or connector. If you can get them disconnected, one method to prevent galvanic corrosion is to just disconnect them regularly to avoid them fusing. Not sure if you’ll remember? You can also use a plastic connector between the hoses to make sure the two metals don’t touch each other or switch out the aluminum hose ends with replacement brass or plastic ends, found at most hardware stores.

Now that you’ve learned about galvanic corrosion, it’s time to get back to gardening. Good luck with those hoses! If you have other gardening questions, please contact your local extension office.