19-05-2022 / 11:32

Water column and waterproofness of your polyester and/or nylon tent

As a camper you have probably experienced it before: you have just pitched your tent and it starts raining cats and dogs. At such a time, it is of course important that your tent is waterproof. But how waterproof is your tent and how is waterproofness measured and declared? And what can you do if your tent starts to leak?


What is water column?

If you look for the waterproofness of polyester or nylon NOMAD tents on our website, you will see that it is indicated by the term “water column”. What does it mean? Water column is the term used to indicate the degree of waterproofness of a certain material. The higher the water column number, the higher the waterproofness of your tent fabric material.

Tents are tested for waterproofness by placing a tube (also called a column) with a diameter of about 2.5 cm against the canvas and then filling the tube with water. As soon as the fabric starts to leak, the test is to see how watertight the tent is. A water column of 4,000 mm, for example, means that the fabric can withstand the water pressure of a tube of water 4,000 millimeters (4 meters) high.

When is a tent waterproof?

Under ideal conditions, a tent fabric is waterproof from a water column of around 1000 millimeters. Because ideal conditions are simply not a given during a camping trip, we use higher minimum values for NOMAD tents (from 2000 mm).

For the groundsheet we use a minimum water column of 5,000 millimeters. In general, the water column of groundsheets is higher than the water column of outdoor tents. Because you stand and lie on them and thus exert a great deal of pressure, groundsheets must be even more resistant to water.

Even with groundsheets with an extremely high water column, we always recommend putting an extra tarp under the tent to protect it. It keeps the tent clean, dry and thus extends its life. Do you use an extra ground sheet? Then make sure that the ground sheet is about 10 centimeters narrower than the size of the tent to prevent water from flowing between the tent and the ground sheet.

The waterproofness of a tent fabric does not say anything about the overall performance of the tent. The waterproofness of the seams, the coatings, the construction, the poles and many other factors must also be considered.



To increase the waterproofness of polyester and nylon tents, a coating is applied to the inside of the tent fabric. Applying a coating is precision work. Especially with extremely lightweight tent fabrics it is important to do this carefully because it makes thin tent fabrics weaker. This is why extremely thin and lightweight tent fabrics often have only a thin coating and therefore a lower water column.

Coatings have the advantage of making the fabric waterproof, but make it less breathable. This means that condensation cannot escape from the inside.


Waterproof seams 

The seams of polyester and nylon tents are taped on the inside. This means that the holes created when sewing the tent are “taped” with transparent tape. This tape is applied by heat.

In a good tent, all seams of the outer tent are taped on the inside. Of course, this is always the case with our tents.

What can you do if your tent starts to leak?

Rain gently tapping on your tent as you lie in it can be very cozy, but wetness inside your tent is something you want to avoid at all costs. If your tent starts to leak somewhere, check the following:

  • Is your tent leaking at a seam? Then it could be that there is a small defect in the taping. Fortunately, there are many repair kits on the market that make it easy to repair seams.
  • Is your tent leaking at the canvas? First make sure you don’t have any objects against the canvas. Pressure against the canvas from the inside can cause leakage. If this is not the case, it could be that the coating of your tent is worn out. The only cure for a worn coating is to buy a new tent.

Despite precautions, there is still a possibility of a drop of rain getting through somewhere.