The world’s LNG fleet has been experiencing a real boom in recent years. In the last 20 years, there has been an exponential growth of this form of ships, and a further continuation of this trend is predicted. Gas as an energy source is increasingly being imposed as an energy source of the future, and its transport has been brought almost to perfection. From the construction point of view, they are extremely difficult to carry out and only a few shipyards dare to accept the LNG ship project. However, the most difficult and demanding part of the project itself is the construction of the drive part. Today, motor-powered ships predominate to a large extent, most often engines from factories such as Wartsila and MAN B&W, but LNG ships from the steam turbine plant can also be found in the world fleet. One of the challenges facing shipbuilders and investors is the construction of part of the fresh water production system, and its treatment to meet strict technological standards related not only as a cooling medium, but also as an indispensable part of human life, drinking water and other use. This is the purpose of various tests and set parameters within which the parameters of the produced ship's water should be located, and whose values are regulated by various chemical additives.