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Can you use dehumidifier water for plants or irons?

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In short

Dehumidifier water is condensed from the air, so it starts out low in dissolved minerals, but it is not distilled or clean. It can pick up dust, airborne particles, microbes and traces of metal from the coils and tank. It is fine for flushing toilets and watering ornamental plants if used fresh, and some people use it in irons where the iron maker allows. Never drink it or give it to pets.

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Pouring litres of water down the sink every day feels wasteful, so it is natural to wonder whether dehumidifier water can be reused. The answer is yes for some jobs and no for others. This explainer covers what is and is not in the tank, why it is not the same as distilled water, which uses are sensible, and simple ways to keep the tank cleaner. It sticks to widely accepted guidance, and for anything to do with an appliance like an iron, the maker's manual has the final say.

Where the water comes from

A dehumidifier condenses water vapour out of room air onto a cold coil, or in a desiccant model out of a heated air loop. Water vapour in the air carries very few dissolved minerals, so the condensed water is soft, a bit like rainwater. That is why it is sometimes compared to distilled water.

The difference is what it touches on the way. The air brings dust, skin flakes, cooking particles, mould spores and anything else floating in the room. The water then runs over the coil fins and sits in a plastic tank, which can hold a film of slime if it is not cleaned. So the water is soft but not pure.

What can be in the tank

The contents depend on the room and how often the tank is emptied and cleaned. These are the main things to expect.

  • Dust and airborne particles caught by the condensing water
  • Microbes, which grow if water sits in the tank for days
  • Traces of metal from the coil and fittings
  • Residue from the tank and float if not cleaned
  • Very few dissolved minerals, so it is soft

Uses that make sense

Because it is soft and free, dehumidifier water suits jobs where it does not need to be clean enough to drink. Use it fresh, ideally on the day it is collected, rather than storing it for weeks.

UseSensible?Notes
Flushing toiletsYesPour into the bowl or cistern
Ornamental houseplantsGenerally yesUse fresh water, not stale
Garden flowers and lawnGenerally yesUseful in dry spells
Edible plants and herbsBetter to avoidUse tap or rainwater
Steam ironsCheck the iron manualSome makers allow, some advise against
Car screenwashCheck the screenwash instructionsMix with the right additive
Cleaning floorsYesAdd your usual cleaner
Drinking, cooking, petsNoNever
Common uses at a glance

Irons and steam appliances

Steam irons and some other appliances can scale up in hard water areas, so soft water can be appealing. Some iron makers recommend a mix of tap and distilled or demineralised water, while others specifically warn against water from dehumidifiers or tumble dryers because of the particles and residue it can carry. Follow your iron's manual. If it does not mention dehumidifier water, filtering it through a fine filter or coffee filter can remove visible particles, but it will not remove microbes.

For humidifiers, CPAP machines, fish tanks or anything medical, do not use dehumidifier water. Use the water the maker specifies.

Note:Never drink dehumidifier water or use it for cooking, ice, pets or medical equipment. It is not treated and can contain microbes and particles.

Keeping the tank cleaner

Water that sits in a warm tank for several days can grow slime and smell. Empty the tank at least daily when the machine is in use, rinse it, and give it a proper clean every week or two with a mild detergent, as the manual describes. Clean or replace the air filter as recommended too, as a clean filter means less dust reaches the water.

If you would rather not empty a tank at all, many machines offer continuous drainage through a hose to a sink or drain. Our guide on how to clean a dehumidifier covers tanks, floats and filters, and the best dehumidifiers for condensation guide notes which models have a drain outlet.

  1. 1

    Empty the tank at least once a day while running.

  2. 2

    Rinse it with clean water before refitting.

  3. 3

    Wash it with mild detergent every week or two.

  4. 4

    Check the float moves freely and is clean.

  5. 5

    Clean the air filter as the manual describes.

Best dehumidifiers for condensation →

How much water to expect

The amount collected varies hugely with the room, the season and the machine. In a heated home through the colder months, a few hundred millilitres to a couple of litres a day is common. During laundry sessions a machine can collect much more. The litres a day rating on the box is measured in a hot, humid test room, so real amounts are lower. Our article on dehumidifier extraction ratings explains why.

If you plan to reuse the water, a tank with a handle and a spout makes pouring easier. Compare tanks in the best dehumidifiers for UK homes guide.

Frequently asked questions

Is dehumidifier water distilled? No. It is soft because it condenses from vapour, but it picks up dust, microbes and traces of metal on the way, so it is not the same as distilled water.

Can you drink dehumidifier water? No. It is not treated and can contain microbes and particles. Do not drink it or give it to pets.

Can you use dehumidifier water for plants? For ornamental plants and garden flowers, generally yes if it is fresh. Avoid using it on edible plants.

Can I put dehumidifier water in my iron? Only if the iron's manual allows it. Some makers advise against it because of particles and residue.

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