How Much Condensation is Produced When Bathing
By Ruth MacEachern
Product Manager
Oct 08, 2025
Our bathrooms are one of the major sources of condensation in the home, but did you know how much water vapour is released into the air when you take a bath or shower?
The amount of water vapour that can be held by the air without condensation forming depends on the temperature. Water is released by the air when the temperature drops such as during the night, or when the air meets a cold surface such as a window or exterior wall.
A comfortable indoor humidity level is between 40% and 60%, however in your bathroom, because of steam being released from a hot bath it can rise well above that. Without proper ventilation to control humidity in your bathroom, high humidity causes condensation, which in turn will lead to damp patches forming where mould can grow.
The amount of water vapour from a bath
Taking a bath can release a surprising amount of water vapour into the air. Typically, between 0.6l to 1.2l (one to two pints) depending on a few key factors:
The relative temperatures of the water in the bath and the room temperature. Hotter water will release more steam, and colder air can hold less water vapour so more of it condenses onto surfaces.
Your bathing habits are also a factor. If you have a long soak and regularly top up the bath with more hot water, steam will be released for longer at higher levels than if you have a shorter bath in cooler water.
Many people opt not to use their bathroom extractor fan when bathing to avoid the disturbance of the noise, however this means that there is less air circulation which means that the humidity levels will rise even higher.
Did you know you can reduce the amount of steam from your bath by starting with cold water and then using hot water to bring the bath up to the most comfortable temperature. This can cut steam production by as much as 80% - and may also help contribute to lower bills!
The amount of water vapour from a shower
A hot shower can release even more water vapour than a bath. Depending on the temperature and length of time you spend in the shower, it will typically release about 50% more steam than a bath!
The reasons why showers release more steam than baths is a combination of hotter water, the spraying action which allows more water to evaporate, and the length of time we spend in them. Couple a long, hot shower with a cold bathroom on a winter day, and you have a recipe for a major condensation problem. Thankfully, there are things you can do.
Reducing bathroom condensation
Ventilation is the key to reducing condensation in your bathroom. Make sure you have a good extractor fan and run it during and for at least 20–30 minutes after you take a bath or shower. This will reduce the amount of time that water vapour remains in the air and keep humidity levels more comfortable. Modern units like the EnviroVent Cyclone 8 feature a built-in humidity sensor that adjusts power levels to remove steam more quickly.
If you find that condensation is forming away from your bathroom, it is possible that whole house ventilation may be more effective. PIV (Positive Input Ventilation) systems work by drawing air into your home from outside and then gently releasing it throughout your house to displace the humid air and help stop condensation leading to damp and mould in all your rooms.
Find out more
Larger families may find that the water vapour released during baths and showers can lead to major condensation problems in their home that may result in mould forming. Our local ventilation specialists can visit your property to identify the sources of high humidity and provide you with help and advice about the best way to solve the issues. Enter your postcode below to find an expert near you and book your free home survey.
