The term "water column" is used to measure a material’s waterproofing ability, indicating the amount of water pressure a fabric can endure before it begins to let water seep through. This measurement is particularly important for outdoor gear such as ski jackets, pants, and mittens, as it helps determine how well the material will perform in wet conditions. The higher the water column rating, the better the fabric’s resistance to water penetration. However, the intended use of the material also plays a role—more intense activities may require additional reinforcement for better waterproofing.
In simple terms, the water column rating measures a garment’s ability to resist water. This is done by filling a narrow tube placed on the outside of the fabric with water until it begins to leak through. If a jacket has a water column rating of 15,000mm, it means the fabric can withstand the pressure of a 15-meter (15,000mm) tall column of water without any water penetrating the material.
The water column is typically expressed in millimeters (mm), and a higher rating indicates better waterproof performance. For example:
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A rain jacket with a 1,000mm water column can withstand the pressure of a 1-meter high column of water before any leakage occurs
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A rating of 5,000mm shows increased waterproofing ability, designed for more challenging weather conditions
In general:
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A water column rating of 1,500mm to 5,000mm is suitable for light to moderate rain
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Jackets with ratings above 10,000mm offer reliable waterproofing for heavy or prolonged rainfall, or for extreme conditions like snow or cold, wet weather
For instance, if you find yourself in a downpour and your jacket can handle a 5,000mm water column, it will protect you from the rain, ensuring you stay dry. However, if you’re expecting to be out in heavy rain all day, we recommend opting for a jacket with a 20,000mm rating for maximum protection.
