Understanding "Fully Waterproof" and What the Millimeters Mean
When you see terms like "waterproof" or "water-resistant" on electronics, clothing, or outdoor gear, it can be confusing. What does "fully waterproof" actually mean, and how do those millimeters (mm) play a role? Let's dive in and break it down for the average American consumer.
The Illusion of Absolute Waterproofness
First, it's important to understand that for most consumer products, "fully waterproof" is more of a marketing term than a literal guarantee of absolute impermeability under all conditions. True, complete waterproofing often involves specialized materials and construction that are expensive and impractical for everyday items. Instead, most products achieve a level of water resistance that is sufficient for their intended use.
The Role of Millimeters (mm)
The "mm" you often see associated with water resistance ratings, particularly in the context of fabrics and textiles like those found in rain jackets or tents, refers to the hydrostatic head test. This is a standard method used to determine how much water pressure a fabric can withstand before water starts to penetrate it.
Here's how it works:
- A section of fabric is held under a column of water.
- The height of that column of water is measured in millimeters.
- The point at which water begins to seep through the fabric is the fabric's hydrostatic head rating.
A higher millimeter rating means the fabric can withstand greater water pressure.
What Millimeter Rating is Considered "Fully Waterproof"?
This is where the nuance comes in. There isn't one single, universally agreed-upon millimeter (mm) number that definitively labels something as "fully waterproof" for all situations. However, we can provide general guidelines based on common industry standards and what's considered highly water-resistant:
- Below 5,000 mm: Generally considered water-resistant, suitable for light rain or splashes. Not ideal for prolonged exposure to heavy rain.
- 5,000 mm to 10,000 mm: Good water resistance. Can handle moderate rain and will keep you dry for a reasonable period in most typical rainy conditions.
- 10,000 mm to 20,000 mm: Very good water resistance. This range is often considered the benchmark for serious rainwear and outdoor gear that needs to perform in heavy rain and challenging weather. Many high-quality waterproof jackets fall into this category.
- 20,000 mm and above: Excellent, high-level water resistance. This rating is typically found in professional-grade outdoor gear, expedition-level equipment, and products designed for extreme wet conditions. For practical purposes, anything above 10,000 mm is often considered effectively "fully waterproof" for most outdoor recreational activities and everyday use.
It's crucial to remember that the hydrostatic head is just one aspect of waterproofing. Other factors include seam sealing, the type of zippers, and the overall construction of the product.
Beyond the Millimeters: Other Waterproofing Factors
While the hydrostatic head rating gives you a numerical measure of a fabric's ability to repel water under pressure, it's not the whole story. For a product to be truly effective in keeping you dry, consider these other elements:
- Seam Sealing: Even the most waterproof fabric will leak if the seams are not properly sealed. Look for products with taped or sealed seams. This is often indicated by a separate rating or a description like "fully seam-taped."
- Waterproof Zippers: Standard zippers can be a weak point for water entry. Many waterproof garments and bags use special waterproof zippers or have storm flaps over them to prevent water from seeping through.
- Durable Water Repellent (DWR) Coating: Many waterproof fabrics have a DWR coating on the outer surface. This helps water bead up and roll off the fabric, preventing it from saturating the material. While this is a water-repellent treatment, not a waterproof barrier itself, it significantly enhances the performance of the waterproof membrane.
- Breathability: For clothing, waterproofing is often paired with breathability. A waterproof material that doesn't allow moisture vapor to escape from the inside can lead to you getting wet from your own sweat. Look for products with both good waterproof and breathable ratings (often expressed in g/m²/24hr).
In essence, for most consumers, a product with a hydrostatic head rating of 10,000 mm or higher, coupled with sealed seams and good construction, can be confidently considered "fully waterproof" for typical use in rain.
Waterproof Ratings for Electronics
For electronic devices like smartphones, smartwatches, and cameras, waterproofing is typically denoted by an IP (Ingress Protection) rating. This rating is different from the millimeter rating for fabrics and indicates protection against both solids (like dust) and liquids.
An IP rating consists of two digits:
- The first digit represents protection against solids.
- The second digit represents protection against liquids.
For waterproofing, we focus on the second digit:
- IPX4: Protected against splashes from any direction.
- IPX5: Protected against water jets from any direction.
- IPX6: Protected against strong water jets from any direction.
- IPX7: Protected against immersion in water up to 1 meter for 30 minutes. This is often considered a good level of "waterproof" for accidental submersion.
- IPX8: Protected against continuous immersion in water under conditions specified by the manufacturer (typically deeper than 1 meter and for longer than 30 minutes). This is the highest level of liquid protection and is what most people would associate with "fully waterproof" for electronics.
So, for electronics, an IP rating with an 8 in the second position is generally considered "fully waterproof" for practical purposes, assuming you adhere to the manufacturer's specific limitations.
When Does "Waterproof" Become a Problem?
It's important to manage expectations. Even the highest-rated waterproof products have limits. Prolonged submersion in deep water, high-pressure jets (like from a power washer), or exposure to chemicals can eventually compromise even the most robust waterproofing.
Always check the manufacturer's specifications and care instructions for your specific product to understand its limitations and ensure its longevity.
Frequently Asked Questions (FAQ)
How do I know if my jacket is truly waterproof?
Look for a hydrostatic head rating of at least 10,000 mm, ideally higher, and ensure the seams are taped or sealed. A Durable Water Repellent (DWR) coating on the outside is also a good sign. Check the product's label or description for these details.
Why do some rain jackets have higher mm ratings than others?
Higher millimeter (mm) ratings indicate that the fabric can withstand greater water pressure before water penetrates. This is achieved through advanced fabric technologies and thicker waterproof membranes, making them suitable for more extreme or prolonged exposure to rain.
Can I swim with an IPX7 rated phone?
While an IPX7 rating means your phone can be immersed in up to 1 meter of water for 30 minutes, it is not designed for swimming. Prolonged submersion, saltwater, and chlorine can still damage the device. It's best for accidental drops in the bath or sink, not recreational water activities.
Why are seam seals so important for waterproof clothing?
Seam seals are critical because the needle holes created during stitching can act as tiny entry points for water. Sealing these seams with tape or a waterproof adhesive prevents water from leaking through these vulnerable areas, ensuring the overall effectiveness of the garment's waterproofing.
