When water is especially high in minerals like calcium carbonate and magnesium, we call it hard water. Roughly 85 percent of the United States has hard water.  It’s perfectly safe for cooking and washing. In fact, some studies even suggest some health benefits to drinking hard water. These include lowered rates of heart disease, decreased risk of some cancers, and increased healthy bone density.

But the strain of hard-water operation can destroy your autoclave.

Limescale Prevention is Essential Maintenance

Hard water has a high concentration of calcium carbonate, which tends to build up inside hot water pipes and appliances. This is especially the case with appliances and devices that heat water, like autoclaves. The resulting build-up (“scale”, “limescale”, or “lime”) jams valves and constricts pipes, diminishing water flow. This ultimately clogs pipes and destroys valves. As scale accumulates, it also acts as an insulator, absorbing energy when you are trying to heat your autoclave’s vessel. This steadily reduces efficiency—eventually by 20 to 30 percent. Given time, scale build-up will drive up utility costs, and strain the autoclave, increasing maintenance while decreasing the autoclave’s working lifespan (even with increased maintenance). 

Scale can build up surprisingly quickly. Ignoring water quality often starts increasing downtime inside a year. But even after replacing valves and gaskets, and cleaning out lime from the chamber, drain condenser, and heating element, lingering traces of scale will continue to degrade the autoclave’s performance and accelerate the accumulation of new scale. 

Check Your Water Supply, Save Your Autoclave

The only real solution is to address hard water at the source. Fortunately, this is extremely straightforward: Installing a “water softener” to capture some of the minerals, reducing the water’s hardness. Even the hardest tap water can be adequately “softened” with a consumer-grade water softener from any big-box hardware store. 

If you are planning on installing a steam autoclave—or have one already—now is the time to check your water hardness. Again, this is extremely cheap and easy. Most labs are on a city water system, so a call to the water company is all it takes to determine if you need to get a water softener installed. 

Generally speaking, water is “soft” when it has below 17 ppm (parts per million) of calcium carbonate, “moderately hard” above 60 ppm, and “hard” when it exceeds 120 ppm. (These numbers may also be given in “grains per gallon,” abbreviated “gpg.” Anything below 3.5 gpg is “soft” and anything above 7 gpg is “hard.”) 

If your water company can’t answer this question, you can test the water hardness with simple test strips from any store carrying aquarium supplies.

Ideally, you want water in the “soft” range. “Moderately hard” water may be fine. If you have “hard” water (120 ppm, or more than 7 gpg), install a water softener. In these cases, a standard water softener will pay for itself in the first six months simply by reducing unnecessary service calls and avoiding all the headaches of unexpected downtime.

[image credit: “hard water” by _gee_ Graeme Maclean is licensed under CC BY 2.0. To view a copy of this license, visit https://creativecommons.org/licenses/by/2.0/?ref=openverse.]