You may have come across the term ‘Hydrostatic Head’ when shopping for tents, jackets, or even groundsheets — the term ‘Hydrostatic Head’ is actually a measurement. More specifically, a measurement as to how tall of a water column the fabric can hold before water starts to seep through the material, which essentially refers to how water resistant the material is.
Take for example a polyester tent that has a hydrostatic head of 3000mm. This would mean that it can hold a column of water that is 3000mm tall. Any more and water will start to seep through the material. Hence, the higher the hydrostatic head value of a material, the more water-resistant it is.
So what would be an ideal hydrostatic value for a tent? Well, if having a higher hydrostatic head means higher water resistance, doesn’t that mean that the highest value possible would be the best? In theory, the higher the value the better it definitely will be. However, hydrostatic head values aren’t the only defining factor when it comes to how waterproof your tent will be.
What Is A Sufficient Hydrostatic Value For A Tent?
Typically, most tents come with a hydrostatic head value of 3000mm, and that would be a good gauge of what is enough to withstand rainfall in the UK. To be able to call a material water-resistant, it requires a minimum hydrostatic head value of 1000mm.
Harsher rain and snowy climates will obviously call for tents with higher hydrostatic head values. If you plan to camp where there is snow or frequent heavy showers, we recommend you look for tents with hydrostatic head values of 5000mm up to 10000 mm.
Tents with hydrostatic head values of above 1000mm would be sufficient for regions that are dry and rarely see rainfall. Since most polyester tents have a minimum hydrostatic head value of 1000mm, finding a suitable tent shouldn’t be that hard.
Hydrostatic Head Values Isn’t The Only Factor To Be Concerned About
Whilst hydrostatic head values are a good indicator of how water resistant a material is, they aren’t the only factor that comes into play when determining how waterproof your tent is.
Even a tent with a hydrostatic head of 10000mm can end up with water seeping through. This is because hydrostatic heads aren’t the sole factor.
The overall build of the tent plays a part in how well a tent can keep water out. Entry points are the crux of the problem when it comes to waterproofing. Water can seep through seams between sheets of materials and zippers.
A tent with a hydrostatic head value of 3000mm that has tightly sealed seams and zipper covers will outdo a tent with a higher hydrostatic head but a flawed design.
If you intend to stay dry in your tent, looking out for the flaws in the design of the tent is as important as looking for a high hydrostatic head. Zippers with covers are a simple way to keep water out and sealed/hidden seams are a great way of preventing water from entering.
Some tents also come with an additional layer of waterproof coating. This allows water to bead off the material and glide down the sides of the tent and into the ground instead. This provides an extra resistance to water, which will aid in keeping the inside of the tent as dry as possible.
Groundsheets typically have a higher hydrostatic head rating than the material of the tent itself. The part of the tent that will come into contact with moisture the most would be the groundsheet, hence the higher ratings.
Much like the rest of the tent, there are, however, other factors to consider when it comes to the groundsheet.
Groundsheets have to be of a certain thickness to prevent wear and tear. Even if you manage to find flat ground to set up your tent, there will inevitably be small rocks and sharp objects on the ground.
This will eventually cause wear and tear over a prolonged period of time, and holes are never a good thing when it comes to water. Worn down groundsheets are susceptible to water leaking in through the ground which would definitely lead to an unpleasant experience.
Can I Increase The Hydrostatic Value Of My Tent?
The short answer would be no. Fortunately, you can, however, increase the water-resistance of your tent. As mentioned above, there are other factors that come into play. We have gathered a few methods to help in ensuring that your tent remains as waterproof as possible and the insides remain completely dry.
A simple way to improve your tent’s water resistance would be to use what is known as seam sealers. Seam sealers help to seal the small holes between stitches at the seams. This creates a watertight seal and hence prevents water from leaking in through the seams. It can also be reapplied when wear and tear effects are noticed at the seams.
A tarp is an excellent addition to have as well, especially when you face strong winds and heavy rain. They provide an extra layer of protection against the rain, covering any form of entry points where water can potentially seep through.
Waterproof coatings are also an option if your tent doesn’t already have one. We also recommend getting a UV coating on your tent as it helps with preventing degradation of the waterproof coating by UV rays. Waterproof coatings don’t last forever, so having a spare bottle of waterproof coating allows you to apply it at any point in time.
The next time you are shopping for a tent, look out for the hydrostatic head rating that comes with it. However, keep in mind that there are other factors to look out for. That being said, hydrostatic head ratings are a good place to start with, and it helps to narrow down your selection. This is especially true if you are planning to do some camping in the rain or snow and require a tent of a certain rating.