Is tumble dryer or dehumidifier water distilled?
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Part of our bottled and other water guide
The tank fills with clear water, and the iron handbook asks for distilled. Is the first the second? You can check how yours compares with your tap using a 20-in-1 test strip.
Short answer: Not in the labelled-bottle sense. The Royal Society of Chemistry defines simple distillation as evaporation followed by condensation, and Which? says condenser dryers and refrigerant dehumidifiers condense water from warm, damp air. A desiccant dehumidifier can reach 80°C inside. In the sources we read, we found no UK official guidance on what the water contains.
By Andrew Tomlinson, WaterKit · Last reviewed 29 October 2026
Is tumble dryer or dehumidifier water distilled?
Not in the way a bottle labelled distilled water is, though the principle is similar. The Royal Society of Chemistry (RSC) defines simple distillation as separating a liquid from a solution through evaporation followed by condensation, and the liquid collected at the end is the distillate. Which? says a condenser or heat pump dryer's heat exchanger cools warm, moist air so the water ends up in the container. If you want to see whether a sample holds dissolved minerals, you can dip a 20-in-1 strip in it and compare it with your tap.
A refrigerant dehumidifier condenses damp air on a cold surface, and a desiccant model heats a moisture-holding wheel, according to Which?. Its separate dehumidifier tips say temperatures inside a desiccant machine can reach as high as 80°C. So the water is condensed vapour that has been through a machine, and none of the pages we read calls it distilled water. In the sources we read, we found no UK official guidance on what it contains, or on drinking it, so we say nothing either way. Our distilled water guide explains the labelled kind.
Can you put tumble dryer or dehumidifier water in a steam iron?
Your iron's handbook decides, and your machine's manual may say something too. The Which? and RSC pages we read do not cover iron water, so we cannot rank it. Our steam iron water guide looks at what iron makers say.
Why might the water from your own machine differ from distilled water?
The textbook picture is an average. Your tank holds whatever your laundry, filters and room air gave it, and a general description of the process does not tell you what is in it. Which? says fibres travel in the steam and air through a condenser dryer's heat exchanger and can clog it over time, so it advises cleaning it under the tap every month or so. It also advises emptying a dryer's water reservoir every time you use the machine. For dehumidifiers, its buying guide says to empty the tank after every use and wipe it with a cloth, so you don't get mould or mildew from stagnant water. Neither page says what the collected water contains.
“I would treat the water from your own machine as its own thing rather than assuming it matches the textbook picture. What ends up in the tank depends on your laundry, your filters and your room, so a quick strip dipped in it next to your tap is a sensible way to see how they differ.”
Your tap water is the other half of any comparison, and it also varies by area, so a strip dipped in both indicates how they differ. Our hardness guide explains how to find your local figure.
What can you use instead of distilled water?
Whatever the handbook for that appliance allows, because the sources we read do not rank alternatives. In the RSC's terms, boiling alone is not distillation, since distillation also collects the condensed vapour. The RSC's teaching notes also say filter paper cannot separate a solution, which passes through unchanged. See boiled versus distilled water, deionised versus distilled water and distilled, filtered and purified water.
How can you check the water from your machine?
Dip a strip and read it. The WaterKit Water Test Kit has a 20-in-1 strip. Fill a clean glass or cup with the sample, dip one strip, wait 30 to 60 seconds and match the pads to the chart, or enter the colours in the free results checker. We have not run strips on this water, so the table is our own reading of the chart, not a test result. It also does not rest on any official figure for this water.
| Pad | Chart steps (mg/L) | What a reading would indicate |
|---|---|---|
| Hardness | 0, 25, 50, 100, 250, 425 | Zero indicates no calcium or magnesium detected at the first step. A higher step indicates dissolved minerals. The unit basis is unconfirmed, so a comparison with your tap is rough |
| Total alkalinity | 0, 40, 80, 120, 180, 240 | Zero means none detected at the first step of 40 |
| Sodium chloride | 0, 100, 250, 500, 1000, 2000 | Zero means none detected at the first step of 100 |
Several things are outside what the strip can do.
- It has no pad for lint, fibres, detergent or softener residue, dust or mould spores. A zero on hardness does not indicate that the water is clean or suits an iron.
- A zero means none detected at that pad's first step, not nothing there. We do not give a pH reading for this water.
- We do not claim the rapid bacteria test for water from an appliance tank.
- A strip result has no legal effect.
Best pack: 20 strips, enough to test your tap and a sample from each machine side by side and repeat the check later, £5.99 (or £10.99 with a bacteria test), with free 2nd Class delivery on every order. See the kit
Your tumble dryer and dehumidifier water questions
Is tumble dryer water distilled?
Not by any label. It is condensed vapour from damp laundry, and we found no UK official figures for what it contains.
Is dehumidifier water distilled? Is water from a dehumidifier distilled?
Not by any label either. It condenses from room air in the tank, and Which? says to empty and wipe the tank after every use.
Can I use water from tumble dryer in iron? Can you use tumble dryer water in your iron? Can I use water from dehumidifier in my iron?
Check your iron's handbook and your machine's manual. The Which? and RSC pages we read do not cover it.
Can you use boiled water instead of distilled water? Can I use boiled water instead of distilled water? Can I use boiled water instead of distilled?
Only where your appliance handbook allows it. Boiling is not distillation in the RSC's terms, because distillation also collects the condensed vapour.
Can I use deionised water instead of distilled?
Check the handbook. Our deionised versus distilled guide sets out how they differ.
Can I use filtered water instead of distilled water?
Only where the handbook allows it. The RSC says filter paper cannot separate a solution, and our filter jug guide covers what a jug does.
What can I use instead of descaling solution?
The sources we read do not cover it, and we found no UK official guidance. Follow your appliance handbook. Our limescale guide explains what the scale is.
Sources
- Which?, Tumble dryer tips and maintenance (dated 21 October 2026; heat exchanger condenses moist air into the container, fibres in the heat exchanger, cleaning monthly, emptying the reservoir; read 29 October 2026). Which? is an independent consumer organisation, not an official body.
- Which?, Best dehumidifiers 2026 (dated 20 October 2026; refrigerant and desiccant types, emptying and wiping the tank) and 5 ways to get the most out of your dehumidifier (dated 2 December 2025; desiccant temperatures as high as 80°C; read 29 October 2026).
- Royal Society of Chemistry, Simple distillation, practical videos, 14 to 16 years (undated page; definition of simple distillation and distillate, and the teaching note that filtration cannot separate solutions; read 29 October 2026).
- We read no UK official source on the contents or use of tumble dryer or dehumidifier water for this rewrite, so the statements that we found none apply to the sources we read.
- WaterKit, Water Test Kit (20-in-1 strip, 30 to 60 second read, optional rapid coliform test read after 24 to 48 hours, from £5.99 for 20 strips, free 2nd Class delivery on every order, 30-day money-back guarantee) and results portal. The strip table is WaterKit's own reading of the colour chart steps.