From the beginning of pet keeping, animals and birds have been offered water in open bowls placed on the cage floor or mounted on the sides of the cage. This is a simple and easy way to offer the water, but we now know that the water in open dishes is easily contaminated. Food particles, droppings, pet hair and any other contaminants carry bacteria into the water and pollute it. Some water dishes attempt to prevent this with partial "hoods", but are still open to having pollutants flipped or tossed into the water supply by playful animals or birds in the midst of wing flapping exercises. The decaying food, fecal matter and disease organisms are then ingested by the animal or bird drinking from that bowl, possibly infecting the pet. The water bottle, in comparison, has a drinking tube that offers a one-way flow of water, preventing particles from entering the water supply. The water remains sanitary for days at a time, drastically reducing the chance of any ingestion of polluted water and subsequent infection.