It does not really matter what sort of outdoor goods you are looking for, the term "water column" will be here quite popular. What is it then ? You can find out in our today´s article.
What does water column mean ?
Especially in a world of outdoor we can see this term almost all the time, but only some of us know, what it really means and how it can help us.
The water column indicates the level of water pressure that a fabric can withstand before water penetrates it. If the water pressure exceeds a certain limit to which the fabric is made, the water starts to penetrate and fabric gets wet.
The higher the better ? Not really
The higher the water column rating, the greater the level of waterproofness, is not completely true. Moreover, you might spend more money than you have to, just because you buy jacket or tent with high water column ratio, that you have no chance to use in our conditions.
How do we measure it ?
The water column is usually stated in milimeteres (mmH2O) and you will surely find different numbers when choosing your outdoor clothing/gear. Different manufacturers use different methods, so it is quite likely that your jacket will have different water column rating than running pants and so on.
How do we measure it? Imagine a cylinder that attaches to a particular material. Water gets onto the cylinder and the material is waterproof until the first three drops penetrate into it. Three drop test is one of the qualified tests for water column ratings.
Water column values
| Hodnoty v mm |
Využití |
| vodní sloupec 500 | vhodné pro deštník |
vodní sloupec 3000 | mírný déšť |
vodní sloupec 10 000 | nepromokne ani při silném dešti |
vodní sloupec 20 000 | vhodné pro lyžařskou bundu |
Permeability
And now we come across another and very important concept. There is a big difference between whether the water runs down or soaks in. Water column relates mainly to free water flowing. If you are sitting on a wet snow, you put pressure on the fabric and water won´t flow but rather soaks in, which means that fabric gets wet and we don´t want that.
Breathability
Breathability is stated in g/m2/24 hours. This means, the amount of water vapour (in mm) that can pass through a square meter of fabric over 24 hours.
The water column is great, but it must go hand in hand with breathability. A 10,000 water column jacket is a decent piece in your equipment, but during physical activity you will sweat in it and eventually get cold. And we don't want that either.
In this case, we appreciate jacket with membrane that literally breathe for us. The membrane starts to work with increasing physical activity and wicks the moisture away from the body. Wouldn´t it be simply enough to get a jacket with high ratings ? Yes, it would, but only for sport activities. If you get jacket with high water column rating and strong membrane, then you will probably be cold during normal walks. And that is also something we don´t want. Therefore, always think about purpose and conditions before you purchase your clothes.
As already mentioned, high water column rating may be keeping the rain off you, but if the material isn´t breathable enough, the moisture vapour won´t be able to escape.
Water column by the tent
Even with tents the water column is highly important and the conditions again play the key role as the standard tent has water column ratings around 1 500 mm and can withstand light rain showers.
For heavy rains it is advised to have tents with water column rating of 2000 - 3000 mm.
For expeditions to mountains or for other extrem conditions, there are tents with ratings around 10 000 mm.
In our conditions, the ratings around 2 500 - 3 000 are sufficient. The most important value can be find by the groundsheet, where the numbers should be higher because of the greater pressure and therefore the risk of penetrating of water is also higher.
Conclusion
It doesn´t sound like rocket science, does it ? When purchasing outdoor clothing or gear, it is really important to think about conditions and general use. Do not hesitate to ask. We are here for you to help.
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- Ondřej Krotil
- This explorer and a criminalistic book author was born at the foothills of Giant Mountains. His biggest hobbies include mysteries, history, criminalistics and much more. Ondřej is currently working on such cases as unsolved murders, unexplained suicides, kidnappings or mysterious disappearances. He had been cooperating with Czech and Slovak media as an investigative reporter. Ondřej would like to make good use of his knowledge in the field of literature.
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