Water treatment plants vary in size but are all critical parts of the infrastructure for distributing drinking water. It is rather common with challenges with humidity due to the water surfaces, different temperatures and the importance to avoid any bacterial growth.


The purification process at a groundwater plant contain different steps depending on the quality of the raw water used. 

It is often a challenge in waterworks to maintain the right relative humidity (RH) level. Especially considering that condensation can occur on the surface of the cold pipes and walls. The humidity load from open water surfaces poses a particular challenge. It is important to keep a temperature difference between the air and the open water surfaces. The water should act as a “cold surface” relative to the air. There will however still be a need for dehumidification of the air.

Even if the air feels dry, there is water in the air. Warm air can hold more moisture than cold. This means that the temperature at the cold surface means that the moisture present in the “dry” air can be precipitated on pipes that usually have a temperature below 10°C.

It is the temperature of the pipes that make up the dew point and it is the one who controls the relative humidity level that must be kept in the space.

In many cases, heating is used to control the relative humidity level. It may help in some cases but not if you have cold surfaces. Warming up the air dies not remove the water from the air, but only allows the air to hold more water. The relative humidity level must therefore be controlled depending on the temperature on any cold surfaces.


A suitable relative humidity level

The relative humidity level needs to be held below 55% (RH) to avoid corrosion and mold, but also to reduce bacterial growth. This requires a controlled relative humidity at the temperatures that can cause condensation on the cold surfaces – not in the air otherwise. See the Mollier chart where the curve for condensation (saturation) is indicated as 100% RH at different temperatures.

We recommend having a dew point sensor connected to our dehumidifier. It then senses the temperature on the coldest surface in the room (pipes or walls) and which then controls the dehumidifier to extract as much water from the air so that condensation does not occur.

Return of Investment calculation

An Airwatergreen FLEX dehumidifier consumes on average less than 400W and a REX consumes on average less than 2250W. The NEXT model has an even lower energy consumption per kg water reduced from the air. Our dehumidifiers only work when the moisture level exceeds the set values and have the same efficiency also at low temperatures..

This provides with a cost-effective solution to avoid damage that may occur due to corrosion and bacterial growth.


Airwatergreen technology allows for installations without the need for the installation of ventilation pipes. This saves a lot of effort and cost at installation! And our dehumidifiers are just as energy efficient at low temperature down to minus degrees, as in warm.

In some cases, the dehumidifier works independently against the set dew point and in other cases it is connected to the existing monitoring system.

The products are built to withstand the tough environment that applies with few moving parts and well thought out material choices and an IP63 classification.

The dehumidifier FLEX can easily be mounted on the wall using a console, in this way keeping the floor free. The water is easily led away with a hose to the sump or any other drain.



At installations in Waterworks, both of our product models can be relevant. REX is used in larger spaces and FLEX in smaller spaces and where the moisture load is lower. We can assist with measurement and assessment of moisture load and give suggestions on how a suitable installation can be designed. Our FLEX dehumidifier has a capacity of 5 liters of water / day, which is more than sufficient in a smaller to medium-sized space. REX has a capacity of 30 liters of water / day, which may be needed in larger halls with open water beds and in larger pipe galleries. Each installation in Waterworks is unique and should be adapted to the moisture load that applies there.


Airwatergreen has installations at more than 70 water companies in Europe. In polymer rooms and filter halls but also pipe galleries. Please refer to our User story page for more information.

Do not hesitate to contact us for a climate investigation to define the moisture levels and to design a suitable solution for your business!