While DWR handles surface moisture, a jacket’s waterproof rating determines how well it stands up to real pressure. This rating, often listed as 5,000mm, 10,000mm, or 20,000mm, is determined by a test called the Hydrostatic Head (HH) test.

In a lab, a piece of fabric is stretched tightly under a narrow tube. Water is slowly added, increasing pressure, until moisture finally forces its way through. The height of the water column, measured in millimetres, becomes the fabric’s waterproof rating.

A 10,000mm waterproof rating means the fabric can resist the pressure of a 10-metre column of water before leaking. That matters because rain isn’t gentle. It’s driven by wind, compressed by backpack straps, and pushed into fabric when you kneel or sit on wet ground.

Higher numbers mean better resistance to sustained rain and physical pressure. This rating forms the backbone of a jacket’s waterproof performance.

How waterproof does your jacket really need to be? The answer depends on how and where you use it. Ultra-high ratings look impressive, but they aren’t necessary for many everyday situations.

Think of it like tyres. Off-road performance is great, but not essential for city driving. Higher waterproof ratings usually mean a higher cost, so the goal is to match the rating to real-world conditions.

Here’s how common waterproof ratings translate to actual use:

• 5,000mm

  Ideal for light rain, short showers, and everyday use. Plenty for walking the dog or commuting, but it can struggle in prolonged, heavy rain.

• 10,000mm – 15,000mm

  The sweet spot for most people. Reliable protection for hiking, camping, and consistent rainfall.

• 20,000mm+

  Built for extreme conditions such as torrential rain, wet snow, and prolonged exposure in harsh environments.

Choose based on how wet you’re likely to get, not how extreme the number looks. Waterproof fabric alone doesn’t guarantee dryness, though.

A jacket’s waterproof material is a great start, but it’s useless if the garment is constructed like a sieve. The surprisingly simple reason most "waterproof" gear fails isn't the fabric—it's the thousands of tiny holes poked into it during manufacturing. Every stitch required to assemble the hood, pockets, and zippers creates a potential entry point for water.

To solve this, brands like Bushbuck use a process called seam-sealing. If you turn a Bushbuck waterproof rain jacket inside out, you’ll see thin, shiny strips of tape bonded over the lines of stitching. This tape physically covers the needle holes, creating a barrier that completes the jacket’s waterproofing system.

When you're shopping, you’ll encounter two key terms.

Fully seam-sealed means every single seam, from the hood to the hem, is sealed for maximum protection. This is the hallmark of a truly waterproof jacket. In contrast, critically taped seams mean only the most exposed areas, like the shoulders, chest, and back, are sealed. This lowers the cost and is often fine for casual use, but water can still sneak in through untaped seams on the arms or sides during a real downpour. All of Bushbuck's rain jackets, including our waterproof puffer jackets, are fully seam-sealed.

So, while a fabric's rating tells you how it handles water pressure, the seam taping tells you how well the jacket is actually built to keep you dry. But blocking rain from the outside is only half the battle. What about the moisture you generate on the inside?

The image above shows the seam tape applied to the seams of the Bushbuck Defender Waterproof Jacket. The Defender is a fully seam-sealed jacket.

Waterproofing is only half the equation. If sweat can’t escape, you’ll still end up damp.

Breathability refers to how well a jacket allows moisture vapour from your body to pass through the fabric. This is achieved through a specialised membrane laminated inside the jacket.

These membranes contain microscopic pores. They are small enough to block rain droplets but large enough to allow sweat vapour to escape. That’s how jackets can be described as both waterproof and breathable.

Breathability is measured in grams per square metre (g/m²) over 24 hours. In simple terms, this number tells you how much sweat vapor can pass through a square meter of the fabric over 24 hours. The higher the number, the more moisture can escape.

• 10,000 g/m² is suitable for everyday use.

• 20,000 g/m² or more is better for high-output activities like hiking in steep terrain - the Bushbuck Alpine Jacket was designed for this very application.

The challenge is striking a balance between keeping the weather out and letting your sweat escape. Strong waterproof ratings combined with good breathability create comfort. But if the outer fabric wets out, breathability drops sharply.

If your jacket appears dark and saturated during rain, that usually means it's wetting out. It doesn’t necessarily mean the waterproof membrane has failed. It means the DWR coating has worn off.

When the outer layer absorbs water, sweat vapour can no longer escape efficiently. The jacket feels heavy and cold, and condensation builds inside.

The good news is that wetting out is often fixable. Here is the process we recommend you follow to restore the waterproof performance of your jacket.

1. CLEAN: Wash the jacket using a specialised cleaner designed for waterproof garments, like Grangers Wash + Repel.

2. HEAT: Apply heat in a tumble dryer on low to medium heat. Heat helps to reactivate the DWR coating.

3. DWR: If needed, apply a new DWR treatment to restore water repellency. We recommend a product like Grangers Performance Repel Plus.

Much like your car, your outdoor gear needs to be maintained to ensure it doesn't break down on you. Taking good care of your waterproof gear will ensure your investment performs well for years.

Choosing a waterproof jacket is about understanding the full system:

• DWR coating repels surface water

• Waterproof rating (Hydrostatic Head) measures pressure resistance

• Seam sealing prevents leaks through stitching

• Breathability rating allows sweat to escape

Here’s a simple guide:

• For commuting and light use: 5,000mm waterproof rating

• For hiking and variable weather: 10,000–15,000mm with fully taped seams

• For mountains and severe conditions: 20,000mm+ with fully taped seams and strong breathability

Waterproof jackets aren’t black magic. They’re engineered systems. Now that you've got an understanding of how waterproof ratings work, you can choose the right level of protection for your environment and activity.

Bushbuck's waterproof jackets and pants range from 10,000mm to 20,000mm and are designed to suit a wide range of outdoor adventure and work. From ultralight 20,000mm / 20,000g/m² rain jackets to 10,000mm rated duck down, canavs puffer jackets.

What does a 10,000mm waterproof rating mean?

A 10,000mm waterproof rating means the fabric can withstand the pressure of a 10-metre column of water before leaking. It’s measured using the Hydrostatic Head test and indicates how well a jacket resists sustained rain and physical pressure from wind or backpack straps.

Is 5,000mm waterproof enough?

Yes, 5,000mm waterproof is enough for light rain, commuting, and short outdoor use. However, it may struggle in prolonged heavy downpours or high-pressure situations like kneeling on wet ground.

Is 20,000mm waterproof better than 10,000mm?

A 20,000mm waterproof rating provides greater protection against heavy rain and extended exposure. It’s better for severe weather, alpine conditions, and long days outdoors. For most everyday use, 10,000–15,000mm is usually sufficient.

What is Hydrostatic Head?

The test works by securing a piece of fabric beneath a vertical tube that is slowly filled with water. As the water level rises, pressure builds against the material until droplets begin to penetrate. The point at which leakage occurs, measured in millimetres (mm), determines the waterproof rating.

For example, a fabric with a 10,000mm waterproof rating is able to resist the pressure equivalent to a 10-metre-high column of water before moisture forces its way through.

Why does my waterproof jacket feel wet inside?

A jacket can feel wet inside due to trapped sweat or “wetting out.” When the Durable Water Repellent (DWR) coating wears off, the outer fabric absorbs water, reducing breathability and causing condensation to build up inside.

What’s the difference between waterproof and water-resistant?

Water-resistant jackets repel light rain but aren’t sealed against sustained pressure. Waterproof jackets have tested waterproof ratings and sealed seams to prevent water from entering during heavier or prolonged rain.