Container glossary
What does WWT mean on a container?
A WWT (wind and watertight) container is a used box whose doors seal and whose roof and walls keep rain and wind out, but which is no longer approved for carrying cargo by sea. It is the usual grade of storage containers, and it is a trade description, not a certificate.
What this grade costs
| Container | Wind and watertight |
|---|---|
| 10 ft container | $1,900–2,900 |
| 20 ft container | $1,300–2,300 |
| 40 ft container | $1,700–2,900 |
| 40 ft high cube container | $1,700–3,200 |
| 45 ft high cube container | $2,700–4,100 |
What a WWT grade promises, and what it leaves out
The grade makes one claim: weather does not get in. It is given by the seller after a look at the roof, the walls and the door seals, and it is the fourth rung of the trade’s ladder, under one-trip, IICL and cargo-worthy and above as-is. Most WWT boxes are retired from shipping fleets, with dents, patches and surface rust that do not affect the claim.
What it leaves out is everything a ship needs. A WWT container’s CSC safety approval has lapsed, so no line will book it. And the grade says nothing about how sound the floor is, how square the frame sits or how the box looks; those are for you to inspect. All five grades are compared in the container grades guide.
Testing a WWT box from the inside
You meet WWT in storage-container listings and depot price lists; the table above shows what the grade costs by size. Because the grade is the seller’s word, test it yourself. Step inside, have both doors closed on you and wait for your eyes to adjust: complete darkness means the shell and the gaskets are sound, and any point of daylight is a path for water.
Then look at the roof from above. Dents that hold standing water are where the next leak will start, and rust that flakes off in sheets is structural where surface rust is not. A worn gasket can be replaced and belongs in your offer; rust-through does not get better. The full inspection is in the buying checklist, and choosing a size for storage in storage container sizes.
Expecting a storage-grade box to sail
The mistake that costs most is buying WWT to send goods abroad because it was the cheapest box on the list. Without a valid CSC plate it will be turned away, and bringing it back into approval means a surveyor’s examination and whatever repairs that examination demands — with nothing in the grade to promise it will pass. If the box may ever travel loaded, buy cargo-worthy to begin with.
The smaller mistake is assuming watertight means dry inside. A sealed steel box still sweats when warm, moist air meets a cold roof. That is condensation, not a leak, and the cure is airflow — see ventilation and condensation.
Frequently asked questions
Is a WWT container good enough for storage?
Yes — wind and watertight is the grade sold for static storage, and it costs less than cargo-worthy. Choose a higher grade only if the unit might one day ship, or if its appearance matters.
Can you ship a WWT container overseas?
No, not as it stands: its CSC safety approval has lapsed, and a line will not load a container without a valid one. It would have to be examined, repaired where needed and approved again first.
What does WWT stand for?
WWT stands for wind and watertight, also written “wind and water tight”. It describes a used container that keeps the weather out, and it makes no claim beyond that.