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Laboratory Test Results

Condensate Water

Ever wonder what is in the water that comes out of a dehumidifier?  Some might guess heavy metals, but what does a lab test say?  Is it safe?

Over the years, we have conducted these tests a few times.  This 2013 test was one of those times.  I found a dehumidifier that was a few years old and had been running in a basement.  After contacting a testing lab, I received a set of clean bottles and filled each set with water from this completely random dehumidifier.  The test results for this unit are here:

Unit 377, metals

Notice that the highest level of any metal was about 75 parts per billion (ppb) or 0.075 ppm, a level that is even safe to drink.

After completing this first test and sharing the results with a gardener, I was told that my test was flawed and that a new unit would have a higher level of metals present.  Again I contacted the testing lab, gathered the materials, randomly chose a new unit, and sent the samples for analysis.  Those results are shown here:

Unit M1267792, metals

As you can see, the new unit came back with similar results. Again, levels that would be safe to drink.

The story continues in early 2015 when I was working with a commercial aquaponics farmer in Wisconsin.  When asked if they would reuse the water from their dehumidifiers with their fish they firmly stated, “NO WAY”.  Like many before them they were concerned that the metals from the dehumidifier would leach out and kill the fish.  After showing them my prior test results, they still refused to use the water because those dehumidifiers are not the same ones they have.  Back to the lab we went… and just to be extra certain we changed labs too.  Would the new lab or these different dehumidifiers give us different results?

The results for the dehumidifier condensate from the aquaponics greenhouse are shown here:

Unit Greenhouse, metals

Again, only very small amounts of metal could be found.  Note that ug/L is equivalent to parts per billion.

The results for the dehumidifier condensate in the aquaponics fish room are shown here:

Unit Fish room, metals

Like the tests before, leaching heavy metals was not a real concern.

The only caveat with the results from the dehumidifiers from the aquaponics farm was the presence of coliform bacteria.  It should be noted that coliform bacteria is naturally present (the constant splashing of the fish) in this environment and not something that originated from the dehumidifier.  For this reason, returning the condensate water to the system is not considered a contaminant as it is already present.  Though this bacteria likely makes the water unsafe to drink for humans, it is naturally found in soil and thus safe to feed their plants.

Until next time….