All decorative fountains produce aerosols. Safe operation and regular maintenance protect guest, employees and visitors from exposure to legionella. Legionella bacteria which causes Legionnaires disease is present in naturally occurring water sources, but it can develop at alarming rates in fountains and ornamental water features if the conditions are ideal. Legionella bacteria multiply in water temperatures of 20-45°C. if the water feature is inside a building or located outside in the sun, the water can warm up to this range. Stagnation of water inside the fountain can occur if the pump is non functional. This can lead to a significant increase in the level of risk of legionella growth. Outdoor water fountains which create a fine mist has a greater ability to spread water droplets on a windy day and is more difficult to maintain at a cool temperature on a sunny day. This is particularly difficult to manage in our tropical climate.