The dye test is described in annex A of the EN 15288-2:2008. A dye test will prove that no ‘dead pockets’ are present in the swimming pool. A dead pocket is a volume of water in the pool where no circulation is present. This can occur in several places at the same time in a swimming pool if the circulation system is insufficient. In these areas the swimming pool water is insufficiently replenished and disinfected, which will lead to local bacterial growth. In most cases dead pockets result from de pool configuration combined with the water treatment plant.
A dye test is executed by first neutralising all chlorine present in the pool. This can be done by adding a small amount of hydrogen peroxide. Then a hose is connected to the chlorine injection point to inject a harmless colouring agent to the supply water. After starting the injection of the colouring agent, the entire swimming pool should evenly colour within 15 minutes. Reconnecting and activating the chlorine injection system after this, will make the colouration disappear.