Using Dehumidifier Water for Plants: What to Know

Many homeowners with dehumidifiers wonder if the water collected in the reservoir can be used for their houseplants. Using this collected water is a way to conserve a resource that would otherwise go down the drain. This article explores the safety of using dehumidifier water for your indoor garden, providing a clear understanding of its properties and how to use it properly.

Benefits and Risks of Using Dehumidifier Water

A dehumidifier creates water by drawing humid air over cool coils, causing water vapor to condense into a collection reservoir. The condensation process leaves behind minerals like calcium and magnesium found in tap water, making the collected water similar to distilled or rainwater. This makes it beneficial for sensitive plants, such as calatheas, orchids, and carnivorous plants, which can be harmed by mineral buildup from hard tap water.

This water is not pure, as air pulled through the dehumidifier can deposit airborne particles like dust, mold spores, and bacteria into the collected water. If the collection tank is not cleaned frequently, these microorganisms can multiply. The water is not safe for human consumption and should not be used on any edible plants, including herbs and vegetables, as this could transfer harmful contaminants.

Another risk involves the components of the dehumidifier itself. The condenser coils are made of metals like copper or aluminum, and trace amounts of these heavy metals can leach into the water as it condenses. While the amounts may be small, repeated watering can lead to an accumulation of metals in the soil, which can be toxic to plants. The quality of the collected water is directly impacted by the unit’s maintenance.

Best Practices for Using Dehumidifier Water

To safely use dehumidifier water for your plants, mitigating potential risks is the first step. The most important practice is to maintain a clean dehumidifier. Regularly wash the collection reservoir and any accessible filters with soap and water or a diluted vinegar solution to prevent the growth of bacteria and mold. A clean machine is less likely to introduce harmful microbes into the water.

Before using the water, inspect your dehumidifier’s manual or check the manufacturer’s website to identify the material of the condenser coils. Units with copper coils may pose a higher risk of metal leaching compared to those with aluminum or coated coils. If you have an older dehumidifier, there is a greater chance of material degradation. It is best to avoid using water from very old units.

When you decide to use the water, consider starting with a small number of less valuable plants as a test. This allows you to observe any negative effects over a few weeks before applying the water to your entire collection. Filtering the water through a coffee filter can help remove some physical debris, but it will not remove dissolved metals or microscopic organisms. Letting the water sit for a day is minimally effective in reducing contaminants.

Comparing Dehumidifier Water to Other Water Sources

Tap water is the most convenient, but its mineral content, chlorine, and fluoride levels can vary greatly by location. While some plants benefit from the calcium and magnesium in hard water, these same minerals can harm sensitive species by building up in the soil. Dehumidifier water is a good alternative as it is free of these minerals.

Clean dehumidifier water is functionally very similar to store-bought distilled water. Both are free of the minerals found in tap water, making them a good choice for plants prone to mineral burn. Using water from your dehumidifier is a free, sustainable alternative to purchasing distilled water, making it an economical option.

Rainwater is often considered the ideal source of water for most plants. It is naturally soft and slightly acidic, and it can contain small amounts of atmospheric nitrogen that plants can absorb. Clean dehumidifier water is one of the closest indoor substitutes for natural rainwater, provided you take precautions to ensure it is free from contaminants.