On the ship, dedicated tanks are provided to store the fresh water. However, they can easily get contaminated. Several methods are used to disinfect water, such as UV light or disinfection of the water with silver ions.

In the below text we would like to clarify the difference between both methods and how they operate.

JOWA Ag-S (Silver Ions) and UV water treatment systems are both methods of water disinfection, but they operate in different ways and have distinct advantages and disadvantages.

The Ag-S system uses silver ions to treat water through an oligodynamic process, in which silver ions at concentrations of 0.01-0.1 mg/L inhibit the metabolism of bacteria. This method has been used for centuries, from storing milk and water in silver containers to treating wounds with silver foils. Silver ions are also effective against legionella bacteria and have a residual effect, meaning that the efficacy lasts for weeks in water even with extreme temperatures.

Unlike chlorine, hot water does not degrade the efficacy of silver ions. The silver ions are introduced into water through charged silver plates in a controlled water stream, and the Ag-S system is designed to take a small water flow and dose silver ions into it, which is then mixed in storage tanks to treat the full volume of water. This allows for a small system and easy installation, and the treated water does not have an altered taste or smell.

UV light is a common way to sterilize fresh water and is effective against all viruses, bacterias and protozoa.

On the other hand, the UV water disinfection process uses UV lamps that emit light at 254 nanometers. The treated water is passed through a chamber and exposed to the UV light, which attacks the DNA/RNA of microorganisms, eliminating their ability to function and reproduce. This treatment is instantaneous but does not offer any lasting efficacy and only works if the water is clear. The UV system is typically installed at the outlet of the water supply pressure set on ships and is designed to treat the full volume of water used, whereas the Ag-S system takes a small flow off the pressure set and then mixes it back into the storage tanks to treat all the water.

The Ag-S silver ion units have some interesting applications in both marine and land-based facilities. For example, Ag-S units are used on yachts for charter, as chlorine dosing systems can cause a bad taste/smell of potable water and spots on bright work during wash-downs. Ag-S units are also used in water bottling applications, as they offer long-term efficacy, unlike UV or Ozone treatments. Additionally, hospital hot water systems use silver ion units to keep the water safe, as chlorine does not work as well in hot water, and hospitals have been found to have legionella bacteria in their hot water systems.

In summary, JOWA Ag-S and UV water treatment systems are both methods of water disinfection, but they operate differently and have different advantages and disadvantages. Ag-S systems use silver ions to treat water, have a residual effect, and are small and easy to install, while UV systems use UV light to disinfect water, are instantaneous but do not have a lasting effect, and only work if the water is clear.