September 10, 2021 8 min read

You did it—hiked a dozen miles deep into a mountain range, dealing with mosquitoes, brambles, and some of the most incredible views along the way. You trekked all the way to your campsite, set up your tent, ate a hot meal, and are ready to finally get some rest. The rainclouds nearing your campsite don’t bother you; you’ve camped in the rain before and always slept cozy and dry. 

This time, however, dripping water wakes you up at 4 a.m. Your tent has sprung a leak! Now you’re scrambling to get something, anything, over your tent to stop the water from getting in. But, it’s too late; tonight, you’re just going to be wet.

Nothing ruins a great camping trip quite like a leaking tent. So, what can you do to fix your tent? More importantly, what should you do before you hit the trail to make sure this doesn’t happen to you? Read our guide to learn how to waterproof a tent like a boss.

What does “Waterproof” Really Mean?

Most modern tents are waterproof or at least water resistant. But what makes a tent waterproof in the first place? After all, water is a molecular substance that can be divided into, well, molecules. So how does a fabric tent repel even the tiniest water droplets?

The answer is, it doesn't—at least not fully. In technical terms, no fabric is truly waterproof in the sense that no water will ever get through it. Fabrics are breathable by nature and under extreme pressure, water will find its way through. However, under normal circumstances, water will not make it through a waterproof fabric unless the water pressure maxes out the fabric’s “waterproof rating.” 

The waterproofness (such a technical term!) of fabric is usually measured in millimeters (mm). It corresponds to the maximum amount of water that can sit on top of the fabric without getting through. So, a fabric rated 1,500 mm in waterproofness can withstand the weight of 1,500 millimeters of water sitting on it without leaking.

If you think 1,500 mm of water sounds like a lot, that’s because it is. In fact, that’s more than the famously rainy city Seattle, Washington gets in a year. In theory, any fabric rated at 1,500 mm or above should stay completely dry even in intense rain. 

But if you’re camping in a tent, you also need to consider groundwater coming from below. When you’re camping over wet ground, your body weight from above can force water droplets through the fabric. And since your body weighs more than rain, a 1,500 mm rating, while strong enough for rain flies and tent walls, would not be quite enough for the tent floors or footprint. 

Therefore, when searching for a tent, you want to stick with fabrics rated 3,000 to 5,000 mm to ensure it has the strength needed to be functionally waterproof. That higher rating allows the tent floor to withstand the higher pressure from your body for days at a time while you’re out in the wilderness. 

Hyke & Byke tents are rated at 5,000 mm on the floor (sometimes called the “bathtub”) and the walls, and the rain fly is at least 2,000 mm—making them waterproof from top to bottom. They’ll hold up and stay dry, even in the most extreme three-season conditions.

How Does Waterproof Fabric Work?

Typically, waterproof fabric is made from different layers of synthetic material. Manufacturers will make waterproof fabric with different specifications and layers, but they usually have at least two layers in common.

When it comes to camping gear, the outside fabric is generally nylon or polyester, which are not waterproof fabrics but do resist water well and are appealing to the touch. Below that, you’ll find a coated membrane, usually made of polyurethane. This layer has microscopic holes that will let water vapors through, but not water droplets, allowing waterproof fabrics to remain breathable even though they’re watertight. 

The outer layer is treated with a Durable Water Repellent (DWR) that makes the fabric fully waterproof. DWR is a liquid polyurethane that bonds with the fabric and seals it against water. When all the layers are combined, you’ve got a fabric that breathes well and is completely watertight. 

What Causes a Tent to Lose its Waterproofness?

Tents, outerwear, and other waterproof fabrics are worn down over time by dirt and oil particles that get ground into the fabric and by the sun, which fades and erodes its surface. The polyurethane coating on the outside fades and loses efficacy with repeated use, and after a few summers in your tent, you might notice that it doesn’t hold up against rain as well as it used to. The same goes for waterproof jackets, pants, stuff sacks, and backpacks. 

Tent seams are also liable to degrade over the years. They’re typically very durable, but once the seam taping starts to wear off, water will collect around the seams and start to seep through and it’s game over. 

Some outdoors enthusiasts respond to this issue by buying new equipment (and that’s a fair solution), but not everyone has the means to reinvest in a brand new tent every few years. The good news is, you can affordably and easily restore your tent’s waterproof qualities. 

Here’s how it’s done.

How to Waterproof a Tent

Find the Leak

If you’ve recently camped on a rainy night, you might already know where your tent is leaking from. The problem with water leaks, though, is that they rarely start in the place that you first notice them. If your tent has lost its waterproof quality, there could be more than one leaky spot. 

Inspect every inch of your tent by looking for holes or tears. Sometimes, the culprit of a leak is as simple as a tiny tear in the fabric. If that’s the case, a patch is all you’ll need. Most of the time, however, leaky tents are a bit harder to solve. 

If the source of the leak isn’t obvious, set up your tent at home to test it out. Use a hose to wet the ground underneath you, set up the tent, and use the hose again to give the tent a nice simulated rain shower. Then, hop in the tent and check to see where water has worked its way inside. Pay close attention to the tent seams, walls/rain fly, or tent floor/bathtub, as these are typical problem areas.

Supplies You’ll Need

  • Rubbing alcohol for wiping tent seams and surfaces to remove oil, dirt, and other particles that prevent effective sealing
  • Wet and dry cloths
  • Water and soap to clean the tent and remove dirt/oil
  • Tent waterproofing DWR spray, which is easy to find online or at your local camping store
  • Seam sealer, which is a bit like household superglue and is also easy to find online or in an outdoors-focused shop 

Seal The Tent Seams

If one of your tent seams is leaking, it’s a good idea to repair all of them. Sealing your tent seams is pretty easy and takes less than an hour (excluding drying time). 

Follow these steps: 

  1. Clean the tent seams. Wipe down each seam with a wet cloth, followed by rubbing alcohol. The glue that was originally holding the tent seams together is now your enemy, and the rubbing alcohol will help get rid of it so that the seam sealer can do its job. 
  2. Brush on tent sealer. Use a specialized sealer for tent seams and a brush or popsicle stick to coat the entire seam. You don’t want it to be too thick or too thin. A coating about a millimeter thick is perfect. 
  3. Wipe excess and let dry. Use a clean cloth or rag to gently wipe the excess sealant. Then, let the tent seams dry indoors or in the shade for at least 6 hours before packing your tent away again. 

After your tent seams are completely secure and waterproof, they’ll remain that way for years. Usually, sealing your tent seams is a one-time, permanent fix. Unless you’re backpacking in harsh conditions for months on end, you’ll only have to reseal the seams once every 8-10 years.

Restore Waterproof Surfaces

Now, it’s time to refresh the urethane coating of your tent with a new layer of durable water repellent (DWR) coating. This will add years to the life of the tent and takes about 20 minutes to do, minus drying time. If you think your old, trail-worn tent could use a new coating of DWR even though it hasn’t yet sprung a leak, it’s well worth it to go ahead and give it a refresh! 

Here’s how:

  1. Set up your tent. The easiest way to refresh your tent’s DWR is when it is fully set up, either in your garage or backyard. 
  2. Wash and wipe your tent clean. You should wash your tent after each long trip as part of your normal post-trek routine. Getting all that dirt and oil out of the tent before you refresh the DWR is paramount to extending the life of your tent. Take a rag or sponge, soak it in soapy water, and wipe each tent surface thoroughly. Once the tent is clean, you can move to the next step—no drying needed (yet).
  3. Coat your tent with waterproofing spray (DWR). Generously coat the tent with DWR spray all around the outside. You need only to spray the outside of the tent, as the coating will soak into the fabric and bond with it as it dries. Ensure that you cover each area of the tent, and don’t leave any fabric untouched.

After you’ve fully coated the tent, wipe it down again with a dry cloth to remove any excess DWR and give the tent a clean, even coat. Then, let it dry for at least 12 hours or overnight in a dry space. 

When that’s done your tent will be back to its original, fully waterproof condition. No more worrying about the weather while planning out your next backpacking adventure—rain or shine, you’ve got what you need to sleep soundly while backpacking!

Tips For Tent Waterproofing

How Often Should I Waterproof My Tent?

Tent waterproofing can be seen as a preventative measure, not just a solution to a problem. Because it’s so easy and affordable to spray on a waterproof treatment, you may feel that you should do it each year at the start of a new camping season. That’s fine to do, but it’s not usually necessary. Good tents for backpacking will last, at minimum, 4-7 years before they start to naturally wear down and need a waterproofing refresh. 

Should I Use DWR Spray on My Backpack, Sleeping Bag, etc.?

If your backpacking gear is made from nylon or polyester, odds are it’s been treated with some sort of DWR. Just like your tent, your hammock-compatible sleeping bag, ultralight down sleeping bag, sleeping pad, and backpack’s waterproofing will degrade over the years. 

You may need to refresh the DWR coating of your backpack and sleeping pad every few seasons, but your sleeping bag shouldn’t see enough wear or tear to need it. Plus, a heavy DWR coating will make the sleeping bag stiffer and harder to compress into a stuff sack.

What Seam Sealer and DWR Spray Should I Use?

It’s more or less up to you—seam sealers and DWR sprays from various brands all use the same basic materials. Many people prefer Nikwax-brand items because they have a long-standing reputation for quality and a lot of trust in the backpacking community. Truthfully, though, no sealer brand is going to be noticeably better than any other.

Never Have a Leaky Tent Again

Learning how to waterproof a tent is almost as easy as actually waterproofing it. Make sure you know where the leaks are coming from, keep your tent clean, and refresh the DWR and seam sealant every few years to keep your tent performing like new. 

When’s the last time you checked your tent for leaks? Have any waterproofing tips for our readers? Let us know in the comments section below!

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