Use rainwater, distilled water or water from a dehumidifier. If the soil is waterlogged, it can cause drooping. Make sure the plant has good drainage and does not sit with water in the saucer. Ferns grown in low humidity may appear droopy. Usually this is caused by chilling.
Ferns are also sensitive to leafshine and insecticides.
This is usually caused by lack of fertilizer. Be sure it is fertilized every other week while it is actively growing. It may also be because it isn't getting enough light. If you are feeding the fern and it still looks too yellow, try fertilizing with a solution of 2 tablespoons Epsom salts per gallon of water. When the whole fern develops and ashy, pale appearance, it is probably very dry.