limpala
Three words appear on almost every outdoor cover, bag and case: waterproof, water resistant, showerproof. Only one of them means anything measurable, and it is not the one you think.
The words are not regulated
For general goods there is no legal definition of "waterproof" and no legal definition of "water resistant". A seller can print either word on a product that survives a light drizzle and on a product you could drop in a canal, and neither is automatically false advertising.
That is why the words are useless on their own and why the rest of this guide is about the numbers that sit next to them.
The IP code, and how to read it
The one specification that means something is the IP code from the IEC 60529 standard. It looks like IP54 or IPX7. The first digit is dust, the second digit is water. An X means that figure was not tested, so IPX7 says nothing at all about dust.
The water digit runs like this:
- IPX3. Spray falling at up to 60 degrees from vertical. Light rain, no wind.
- IPX4. Splashing from any direction. Rain with wind in it. This is where most so called showerproof products actually sit.
- IPX5. A low pressure jet from any direction. A hose at a distance.
- IPX6. A powerful jet. Heavy hosing, driving rain on a roof rack.
- IPX7. Immersion in one metre of water for thirty minutes.
- IPX8. Continuous immersion deeper than one metre, on conditions the manufacturer has to state.
The trap: higher is not always better
The water digits are not a straight ladder. IPX7 is tested by holding the product still under water. IPX5 and IPX6 are tested by firing a jet at it. A seal that keeps out standing water can still leak under a jet, because a jet arrives with pressure behind it.
So a product rated IPX7 is not automatically safe under a hose. If both matter to you, look for a dual rating written as IPX5/IPX7 or IP68 with the jet test stated separately. If the listing shows only one number, assume the other test was not passed.
What the rating does not cover
Three things sit outside the test entirely, and all three are where covers and bags fail in real use.
Time. IPX7 is thirty minutes. A garden furniture cover sits in the rain for three days. Nothing in the IP code describes that.
Seams and zips. The test is done on the finished product, but a stitched seam is a line of holes. On a cover, the seams are almost always the first place water gets in. Look for taped or welded seams, and for a storm flap over the zip, which is a strip of fabric that covers the teeth. A zip on its own is not a seal unless it is specifically a waterproof zip.
Age. Coatings wear off. A polyurethane coating on the inside of a fabric cover has a life measured in seasons, not years, and UV shortens it. A cover that was genuinely waterproof in year one can leak in year three without ever being damaged.
What to look for instead of the word
For a cover, tarpaulin or outdoor bag, four details tell you more than any adjective.
- The material and its weight. Polyester or polyethylene, and the gram weight per square metre. A heavier fabric at the same coating lasts longer.
- The coating. PU or PVC coated, stated on the listing. No coating stated usually means no coating.
- The seams. Taped, welded or simply stitched.
- UV treatment. Anything that lives outside in summer needs it, and without it the fabric goes brittle before it goes leaky.
And one thing that has nothing to do with water
A cover that keeps every drop out also keeps every drop in. Furniture that is put away slightly damp under a fully sealed cover will grow mould rather than dry out. That is why good covers have vents, and why a vent is not a manufacturing fault.
If you are covering something that gets wet before it gets covered, breathability matters as much as the rating. Look for vents at the top and for a cover that does not reach all the way to the ground.
The short version
Ignore the adjective. Find the IP code, check whether the second digit was tested for immersion or for jets, then look at the seams and the coating. If a listing gives you an adjective and nothing else, it is telling you that there is no number to give.