Why you shouldn't trust the waterproof rating on your tent

When shopping for the best tent for a UK camping trip, you're always likely to choose one with a high level of waterproofing. So why is it so common to find water inside your tent?

Even if the forecast says you're in for a scorcher there's a chance the weather could turn, so we recently put 10 popular pop-up tents to the test to find out which ones survive the unpredictable British weather.

Each tent was pitched for three days and endured several rain storms, and after less than 24 hours some tents with high waterproofing ratings had puddles in them.

That's because hydrostatic head waterproof ratings aren't everything when it comes to keeping water out of your tent, but sadly they're often all you have to go on when shopping for one.

Read on to find out why you should take tent waterproof ratings with a pinch of salt, tips on keeping your tent rain and condensation-free, and which pop-up tents we managed to pitch and pack down the quickest in our tests.

Head straight to our list of the best pop up tents to find out which ones survived three days of heavy rain

Hydrostatic head ratings explained

You might come across a tent with a waterproof rating of 2,000mm and assume that it means the tent will put up with 2,000mm of rainfall before it leaks. But it doesn't quite work like that.

What it actually means is if you press a column of water 2,000mm high against the tent's canvas, the water wouldn't go through it.

These are called hydrostatic head ratings, which aren't very easy to quantify but can be understood by following a simple rule that the higher the number, the more water the canvas can withstand.

However, we've found that high hydrostatic head ratings don't always mean good waterproofing overall. In our tests, there were two tents with matching hydrostatic head ratings of 3,000mm, and while one was bone dry at the end of testing, the other had a large puddle inside.

This is because most leaks in tents don't come through the canvas, they come in through the seams and zips.

If the seams and zips haven't been stitched and sealed together securely, water will leak into the tent regardless of how repellent the canvas is.

If there's a lot of water ingress at a certain point along a seam or near the door of your tent, it's likely to be a problem with the stitching and should be covered by your tent's warranty.

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How to keep your tent as dry as possible

• Open the vents Even in dry conditions there's plenty of moisture in the air, so it's a good idea to keep your vents open where possible during your camping trip. Good air circulation will help the moisture escape outside.
• Avoid touching the walls and ceiling Applying pressure to the canvas when the tent is pitched risks breaking the surface tension between water on the outside and the canvas underneath, which will funnel that water through the canvas at the point of contact.
• Watch out for doors that open inwards If it's rained recently, lots of water droplets will sit on the door and if it opens inwards all that water will run off the door into your tent. Take care to hold the door and pull it outwards as you're unzipping it.
• Keep wet gear out of the bedroom Damp clothes bring much more unwanted moisture into the tent, and because it has a waterproof shell that moisture won't have anywhere to go as your gear dries. It will likely condense on the ceiling and make your sleeping area damp.
• Open doors and windows for a couple of hours every day As mentioned above, air circulation is key to keeping moisture out of your tent. It's a good idea to prop the doors and windows open for a couple of hours a day to give the circulation a boost.

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Is my tent leaking or is it condensation?

It's common to wake up in the morning to see droplets of water sitting on the ceiling of your tent.

This is most likely condensation rather than a leak, and there's little you can do to eliminate it from your camping experience.

Lots of moisture floats around in the air we breathe, and because the ceiling of your tent is a waterproof barrier the moisture finds it difficult to escape back outside.

The air inside the tent also tends to be warmer than the canvas, causing the moisture to condense into a liquid form when it touches the ceiling.

Campers inside a tent also cause condensation to form. Over the course of one night's sleep a person can breathe out as much as one pint of water into the air. Even with good air circulation it's difficult for all of that moisture to escape your tent.

As advised above, taking steps to keep your tent as ventilated as possible will help to reduce condensation. Don't hurry back to the shop to return your tent if you do find the ceiling a little damp, though.

Water ingress from a small single point or consistent heavy leaking is likely to be a leak, but damp or water droplets in a patch on the ceiling is probably just condensation and nothing to worry about.

Check out the best head torches.

Watch: what's the fastest pop-up tent?

See our tests in action as we timed and judged the speed and convenience of pitching and packing away 10 popular pop-up tents.

Still need more help? See our guide to choosing the best family tent.