A Guide to Waterproofing & DWR
Waterproofing is essential for outdoor clothing and equipment to protect against the elements.
Whether you're braving the rain or facing damp conditions, understanding how waterproofing works can help you choose and maintain the right gear. This guide breaks down everything you need to know about waterproofing, Durable Water Repellency (DWR), and how to keep your gear in top condition.
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What is Waterproofing?
Waterproofing refers to a garment or fabric’s ability to resist water. It’s measured by specific standards, such as Hydrostatic Head (HH) or Pounds per Square Inch (PSI). These tests determine how much water pressure a fabric can withstand before it starts to leak, ensuring reliable protection in wet conditions.
How Waterproofing is Measured
Hydrostatic Head (HH):
– A tube of water is placed over the fabric, and the water pressure is increased until the material leaks.
– The height of the water column (in millimetres) when the fabric starts to seep is the Hydrostatic Head rating.
Example: A 1500mm HH can withstand light rain, while higher ratings like 5000mm or more are better for heavy rain.
Pounds per Square Inch (PSI):
– Measures the pressure a garment can endure, from the force of rain to the weight of a backpack.
– A British Standard PSI of 3 equals 1500mm HH, while high-performance gear often exceeds 40 PSI.
The higher the HH or PSI, the more waterproof the material, but this usually comes with a higher cost.
Types of Waterproofing
Waterproofing comes in two main forms, each suited to different needs:
Coated Fabrics with Breathable Membranes
– These fabrics have a thin layer of polyurethane coating applied to their inner face.
– Sealed seams prevent water from seeping through stitched areas.
– Breathability is achieved by allowing body heat and sweat to escape, ensuring comfort even during strenuous activity.
– Examples include GORE-TEX and eVent, which use microporous membranes that block water but allow moisture vapor to pass through.
Durable Water Repellency (DWR)
– A chemical treatment applied to the outer fabric, creating a barrier that causes water to bead up and roll off.
– Unlike full waterproofing, DWR enhances water resistance and reduces condensation, improving the garment's breathability.
– Over time, dirt, oils, and washing degrade DWR coatings, requiring reapplication to maintain performance.
Examples of Advanced Waterproof Fabrics
GORE-TEX: A well-known microporous membrane that’s both waterproof and breathable, with variants like Pro Shell for extra durability.
Paramo: Mimics the water-shedding properties of animal fur, pushing moisture away from the body while remaining breathable.
Pile/Pertex: A two-layer system that keeps you warm and dry by using body heat to manage moisture, ideal for colder temperatures.
eVent: Similar to GORE-TEX but skips a polyurethane layer, speeding up evaporation and enhancing breathability.
Waterproofing in Action
Waterproofing is used in clothing, footwear, and tents, each with unique considerations:
Clothing: Features like adjustable cuffs, sealed seams, high collars, and storm flaps enhance protection. Waterproof jackets often pair DWR with membranes for optimal performance.
Footwear: Membranes like GORE-TEX keep water out while allowing sweat to escape. Moisture-wicking liners also help maintain dryness.
Tents: Waterproof ratings are critical, with materials needing a minimum Hydrostatic Head of 1500mm to be classified as waterproof. Flysheets and ground sheets typically have higher ratings for added durability and protection.
Changes to DWR – A More Sustainable Future
For years DWR has been built using perfluorinated compounds (PFCs), including long-chain (C8) fluorocarbon-based treatments which are known for their high durability and waterproofing abilities, allowing water to bead off the jacket without being absorbed by the material. Although this C8 treatment is highly effective, the by-products it produces are toxic and do not breakdown in the environment. Considering this, Governments globally have required the manufacture of C8 DWR cease, which has pushed to focus to a more sustainable and environmentally friendly product.
Many outdoor brands adopted shorter-chain C6 treatments to align with the guidelines put in place. C6 treatments have by-products which do breakdown faster than that of C8, so is a step in the right direction from the industry, but many brands are looking for alternatives which allow them to be PFC free, but with the same performance capabilities as C8 treatments previously allowed.
A PFC-free DWR is intended to made to breakdown over time, but it isn’t as resistant to wash and wear, meaning it’s important to care correctly for your products to ensure they continue performing at their best.
Caring for Your Waterproof Gear
To ensure your gear stays effective, regular cleaning and reproofing are essential:
Cleaning: Use specialized cleaners like Nikwax Tech Wash or Granger’s Extreme Wash-In. Avoid regular detergents, as they can strip waterproof coatings or clog breathable membranes.
Reproofing: Reapply DWR treatments every 4–6 months, depending on usage. Choose spray-on solutions for outer coatings and wash-in treatments for membrane-based gear.
Heat Activation: After applying a DWR treatment, use a tumble dryer or iron on a low setting to reactivate water-repelling properties.
Proper care extends the life of your gear, ensuring it performs well season after season.
Shop All Waterproof Sprays & CleanersThe Benefits of Reproofing
Over time, DWR coatings wear down due to dirt, oils, and environmental factors. This can make waterproof gear feel like it’s leaking when its breathability has been compromised. Reproofing is a cost-effective way to restore your gear’s performance without replacing it entirely.
Understanding waterproofing and DWR treatments can make a significant difference in the performance and longevity of your outdoor gear. By choosing the right materials and maintaining them properly, you’ll stay dry, comfortable, and ready for any adventure. Whether it’s a reliable GORE-TEX jacket, a sturdy waterproof tent, or breathable hiking boots, taking care of your gear ensures it keeps up with your outdoor lifestyle. For more expert tips, visit the GO Outdoors guide to GORE-TEX below.
A Guide to GORE-TEX Shop All Waterproofs