Really Cheap DIY Dehumidifier

I’m counting this as a homeschool science project that I didn’t expect to work, but it did. In our area, dehumidifiers are hard to find these days, so a DIY alternative is really our only option. Some quick research suggested calcium chloride could work, but since we don’t have icy roads around here I was skeptical we’d be able to find it.

In fact, we intially could only find iodized table salt. So, we bought about half a kilogram of it, put it into an open container, and left it out overnight.

In the morning, it seemed to have hardened a bit, but the results were far from impressive. We thought it might be helping a little bit, but my quest to find other options intensified.

Eventually, I found a small grocery store that sold iodized sodium chloride rock salt, and I bought two kilograms of it. We put one kilogram in each of two different places in one room, with both locations almost directly under ceiling fans.

The next morning, in addition to feeling better, we noticed water droplets around the edges of the containers. If you have children, as we do, at least one of them is going to ask where the water came from. That was a great conversation, but the science is beyond the scope of this article.

We then poked holes into the rock salt to increase the surface area. That’s a bit advanced for our youngest children to understand, but their elder siblings could follow along.

We soon noticed that these holes were filling up with water, so we made even more holes. Already, the rock salt was greatly outperforming our initial experiment with table salt. We can only imagine the additional success we might be having if we could find calcium chloride around here.

After several nights, enough water had accumulated that, like you have to do with a regular dehumidifier, it had to be drained. That’s as easy as tilting the container and scooping out the water with a spoon. Rock salt here is cheap enough that scooping out some of it accidentally is not cause for concern.

We’ve already gone ahead and purchased more rock salt. So far, we’ve saved significantly over buying a regular dehumidifier, and we’ve also not increased our electric bill. Most importantly, the presence of water where salt used to visibly be captures our childen’s attentions and gives us an opportunity to talk about science. So far, the more water we see, the more great questions we get to explore together.

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