Along with comfortable, non-slip shoes, the rucksack is the hiker's most important tool. Even on bike tours, a small model is usually enough to stow the bare essentials for the day. Some provisions for the rest at the summit, personal documents, sunscreen and a light jacket. It doesn't take much more to be on the safe side. But what if the weather changes on the way and rain clouds gather? Then a waterproof backpack is worth its weight in gold.

In the following article you will find out what waterproof means, what the water column stands for and which backpacks are waterproof on short and longer tours on foot or by bike.

Whether it's a rain jacket, backpack, cell phone case or hiking boots: waterproof means nothing other than that no water penetrates through the material and thus onto the smartphone, into the socks or inside the hiking backpack. As a rule, special membranes ensure that only the surface of the backpack or jacket absorbs the water, so that even large amounts of rain "stay outside". Like this model from Proviz, which is also made of 100 percent reflective material.

Now you might ask why there are additional items of clothing whose material is declared as "water-repellent" or "waterproof". The decisive difference: Waterproof fabrics allow the raindrops to ricochet off. In the event of continuous and heavy rain, however, they will eventually have to admit defeat to the masses of water. This calls for standards that customers can use as a guide so that they don't suddenly end up in the woods like watered poodles on vacation. With this lightweight from 4Monster, the zipper should be waterproof, the fabric itself should at least be water-repellent.

The hydrostatic head is the international standard that the textile industry uses to make transparent how the water permeability of a fabric is measured. Or to put it another way: how long it takes until a certain material or membrane can no longer hold back. In Europe, DIN EN 343:20210-05 is authoritative. To determine the water column, the substance to be tested is exposed to water in the laboratory and the pressure is gradually increased. The so-called Suter test ends as soon as the third drop has penetrated the material and is visible on the inside. If this happens at a water pressure of 0.5 bar, this corresponds to a water column of 5000 millimeters. In Germany, textiles are considered waterproof from a water column of 1500 millimeters. At least if no additional pressure is exerted on the fabric. For example, the straps of the backpack press on the rain-soaked shoulders, a larger water column is needed to get home dry. The wind can also play a role.

With some backpacks (here a model from Semptec), instead of the water column, an IP class provides information about how well the material protects against shocks and water. For example, protection class IPX6 means that the processed material is protected against jets of water and temporary flooding. Read here what the protection classes mean in detail. A waterproof backpack is also important for outdoor fans who plan tours with a canoe or other boat. But be careful: only very few backpacks are waterproof even during a longer dive. This YEAZ backpack for day trips was made of tear-resistant tarpaulin. It is said to be extremely water-resistant, but not completely waterproof. The weak point in such backpacks is often the so-called roll-top closure. With classic backpacks, the zippers are usually the first to lose the fight against the water.

Anyone who already has a good-weather backpack (without a water column) in their closet does not necessarily have to buy a new one. To be prepared for unexpected rain showers, all you need is a rain cover that is slipped over the backpack and is usually bomb-proof thanks to elastic or drawstrings (here's a flexible model from Vaude). However, before you buy the rain cover, always check the volume of the backpack so that the cover fits properly.

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