Impatiens are prone to a number of diseases, many of them carried in the soil or by insects such as thrips. Because you plant in the same places every year, your disease problems may be carried over from season to season in the soil or plant residue. You may also be overwatering, which can create a perfect habitat for fungal or bacterial organisms. Impatiens shouldn't need to be watered every day unless they are in the sun. I suggest you amend your beds with good compost; impatiens need soil with a lot of organic matter, which holds moisture, and good drainage, which allows air to reach the roots. Impatiens planted in containers should be in sterile potting soil. Thrips are tiny insects that feed on impatiens and can spread viral diseases. If you think the problem could be thrips, prevent an infestation from developing by using soap sprays. Be sure to get good coverage on the undersides of the leaves, and repeat the application several times. Once plants are infected with the virus, it's too late to spray. Finally, make sure that you're buying high-quality bedding plants. If any of them show signs of disease or stress in the store, pass them by. If you still have problems, perhaps you might take a year off from impatiens and plant coleus, begonias, or another colorful shading-loving plant to try to break the disease and pest cycle.