The water collected by a dehumidifier can be repurposed to hydrate plants, but only with necessary treatment steps and major caveats. This condensate is essentially atmospheric moisture that has been condensed. It is free from the mineral salts found in tap water, which benefits certain plants. However, the collection process introduces significant contamination risks that must be addressed before the water is used.
Understanding the Water’s Composition and Potential Contaminants
The water produced by a dehumidifier is a condensate, meaning it starts as nearly pure water vapor, but it is not equivalent to commercially distilled water. As the air passes over the unit’s cooling coils, the condensed moisture picks up various particles and contaminants from the surrounding air. This makes the collected liquid only as clean as the air quality and the internal cleanliness of the machine itself.
One source of contamination is the internal hardware of the dehumidifier, which can leach trace amounts of heavy metals into the water. The cooling coils and internal components are often made of materials like copper, aluminum, or galvanized metal. As the condensate runs over these parts, especially in older or poorly maintained units where corrosion may be present, minute amounts of these metals can dissolve into the water.
The standing water in the collection reservoir provides an ideal environment for microbial growth. Airborne contaminants, such as bacteria, mold spores, and dust particles, are trapped along with the moisture. If the tank is not emptied and cleaned regularly, these microorganisms can multiply rapidly, potentially introducing pathogens or fungal spores to the plant’s root system.
Essential Treatment Steps Before Watering Plants
Because of the biological and metallic contamination risks, the collected water should not be used directly from the reservoir. The most straightforward and effective method for sanitizing the water is to bring it to a rolling boil for several minutes. This high-heat treatment successfully eliminates any viable mold spores, bacteria, or other microorganisms collected from the air or grown in the standing water.
After boiling, the water must be allowed to cool completely before being applied to plants to prevent root shock. It is also beneficial to aerate the water during the cooling process, such as by pouring it back and forth between two containers. Aeration helps to restore dissolved oxygen levels that are depleted during boiling, making the water healthier for the plant’s roots.
Simple filtration steps can remove larger particulate matter like dust, hair, or debris that the dehumidifier collected. Pouring the water through a fine mesh strainer or a coffee filter physically removes these larger contaminants. Minimizing the initial contamination load is also achievable through regular maintenance, requiring the collection tank to be scrubbed and disinfected weekly.
Plant Specificity and Long-Term Considerations
The water’s lack of dissolved minerals, while a concern for long-term use, makes it particularly well-suited for specific types of plants. Plants that are sensitive to the mineral buildup common in tap water, which can leave a white crust on the soil, benefit significantly. This includes specialty plants that thrive on soft water with low total dissolved solids.
Examples of plants that benefit include:
- Carnivorous species
- Orchids
- Ferns
- Air plants
The absence of minerals means the water lacks the micronutrients that most common houseplants and garden varieties require for sustained health. Long-term, exclusive use of dehumidifier condensate will lead to nutrient deficiencies, causing yellowing leaves and stunted growth without supplementation. The water itself does not contain the necessary elements like calcium, magnesium, or other trace minerals found in municipal water or rainwater.
A balanced application strategy involves using the treated dehumidifier water strategically rather than as a sole source. It can be combined with a standard liquid fertilizer regimen to provide the missing nutrients. Alternatively, the low-mineral water can be used occasionally, such as once a month, to flush out the accumulated mineral salts from the soil left by regular tap water, preventing harmful buildup.