How to Prevent Container Rain?
Published On:January 3, 2020 Revised On:January 11, 2023

How to Prevent Container Rain?

Transporting cargo on ships in containers is vital for the economy. Imports and exports make a massive impact on the economy, and therefore maritime trade is critical. When goods are transported, there is much investment involved. When packaging damaged due to circumstances that result in container rain, when goods transported are damaged, it causes a considerable loss.

What is Container Rain?

Imagine a jug of water. Suppose this jug of water faces a temperature difference. In that case, you may have noticed water condensing and forming droplets on the sides of the jar — a simplified explanation of what happens during container rain. When a full container load container is packed in one part of the world and transported to another, the difference in temperature tends to make the moisture in the air condenses in the colder areas of the container. Condensations are causing moisture to expand, rise to the top of the container when the container heats up again, clinging to the walls and the ceiling. The moisture on the walls of the container is known as container sweat. As temperatures rise, moisture climbs up the interior of the container before dripping down. The process where the water drips down is called container rain. This container rain can destroy cargo by promoting the growth of mould or even corroding equipment.

Damage Caused by Container RainContainer rain

Exposure to moisture is never a good thing for goods transported. It can cause equipment to get damaged; it can cause corrosion and even promote mould growth. Up to 10% of the goods transported via ships are rejected solely because of the damage caused by container rain. For this reason, efforts were made to eliminate container rain.

How to Eliminate Container Rain?

When considering the reduction of condensation in a container, two main factors need consideration. Firstly, the amount of water vapour present in the container was reduced. Secondly, allowing the warm moist air to escape. These two issues are fundamental and dealt with in several ways, such as:

Inspect Container for Visible Moisture

Before loading the vessel, check if there is any visible moisture in it. If there is any moisture present, wipe it off. It is a simple yet effective method used.

Environmental Considerations

If the container is stored in places with a broader diurnal temperature range, more precautions are taken against container rain. A more considerable temperature difference will cause the moisture in the rain to condense within the container.

Considerations to be Made Based on Cargo

Different cargo has different thresholds for moisture. For instance, wood tends to have the capability to carry much moisture. It means that condensation can cause water vapour from wood to cause container rain. Ideally, this wood must be dried and free of moisture.


If the walls are insulated, the effect of temperature will not be too strong. It means that proper insulation would allow for less difference in temperature, which would allow for less container rain.


Suitable containers with ventilation kits can help maintain a build-up of warm air in the container.

Dehumidifiers and Air-con Units

Although this method is relatively expensive to implement and run, air conditioners and dehumidifiers effectively keep stable dry conditions for the most moisture-sensitive container contents. These do, however, require a source of electricity, without which they are at risk of failing.

Choice of Pallets

Pallets are the structural foundation of a unit load that allows handling and storage efficiencies. Using the right pallet can make all the difference. If a wood pallet is used, there is a higher chance of container rain as wood can retain much more water content.

Place Desiccants in Container

Desiccants are hygroscopic substances that absorb moisture from the atmosphere, making them drier. Using these can drastically reduce the amount of moisture present within the vessel and thus reduce container rain. These moisture-absorbing substances are easy fixes to the moisture content within the containers. A typical example of this type of substance would be desiccant clay. Desiccants are packaged in various forms but are commonly contained in strips on the walls or bags on the container’s floor. There are several container desiccants available. Some of the best ones are as follows:

  • Container rainHumi Dryer Bag contains a non-toxic natural clay desiccant mixed with a small amount of calcium chloride, which can absorb water vapour to up to 80% of its weight. It is suitable for coffee beans, canned foods, flour, rice, etc.
  • Humi Dryer contains a specially formulated desiccant made from a polymer gelling agent and calcium chloride. It can be used while shipping canned foods, coffee beans, flour, rice, etc. It is non-toxic and is of food grade. It has a vapour absorption rate of up to 280% of its weight.
  • Humi Dryer Pole This can be placed within a shipping container conveniently without the need for a ladder. It can be secured either by leaving it on the floor or directly hooking it onto the container wall ring. Specially designed to fit in-between the grooves of the shipping container walls to not only protect your cargo from water vapour but also allow maximum shipping space. It can be used with food-related commodities such as coffee beans, canned foods, flour, rice, and non-toxic and food grades.
  • Humi Dryer Strip is made of non-toxic natural clay desiccant mixed with a small amount of calcium chloride. It is capable of removing moisture from shipping containers. It is non-toxic and food grade.

In conclusion, container rain is a menace that can cause many problems like corrosion and promote moulds and fungi’ growth. There are several ways of avoiding this, and desiccants are a very excellent method. One must try to have as little of this phenomenon as possible, as this is very bad for business.

Here is a video about Container Desiccants that prevent container rain.