Certainly you mean no pump noise. We of ThirstyCats consider pump noise to be completely unacceptable and we test every pump before and after we install it. There are though some brands of cat fountains and pet fountains in which the pump is quite loud, as so many of the reviews state. Those are not ‘quiet cat fountains’. To know which brands are guilty of this, simply read the 3 and 2 star reviews of various brands on Amazon to learn which cat fountains are most likely to irritate you with their unpleasant noises. But not just you. Cats are extremely sensitive to noise and most will stay away from a noisy pump.
Most makers of cat fountains realize that people don’t want to hear pump noises so most brands do use quiet pumps that are not offensive. It is important to realize though, that a quiet cat fountain can become less than quiet if the pump needs cleaning.
What happens is that either cat hair or other debris gets into the pump, or, mineral deposits build up on the pump’s impeller and impeller shaft, creating friction between the moving impeller and the shaft it fits over. If this happens the pump can become somewhat noisy and you no longer have a quiet cat fountain. Pumps can be difficult to access in some brands of cat fountains. (With a ThirstyCat fountain the pump is easily accessed and easily cleaned). See this page.
Another cause of a cat fountain not being quiet can be how the water falls and what onto. Most makers have this sorted but there are a few in which the water falls onto a hollow plastic piece causing a plasticy thrumming noise which is unpleasant. Avoid plastic fountains and you’ll be spared that.
To some people the sound of water falling into water or onto anything else is just plain noise. Others love the sound of moving water and find it soothing. If you are of the first category you want a fountain with no stream or a very short stream (an inch or less) or a stream falling onto a sloped surface (but not a plastic surface which is generally hollow beneath and creates a cheap, plasticky, thrumming sound. Some brands (ThirstyCat Fountains is the only one we know of at this writing) create ‘Bubble-up’ designs with an upward flow and are absolutely silent on medium and low settings, as are our Raised Bubble-up designs.) More on these designs below.
which can vary considerably, depending on the design of the fountain and how the water is delivered.
Generally, the more water and the further it is falling the greater the water sounds. A thin stream makes more of a trickling sound but if forceful can be quite loud and to some annoying. A wider stream makes more of a pouring sound and an agitated or turbulent stream makes a more variable sound and is louder than a smooth stream which creates a softer, steady tone. Below is one style with a broad stream falling a couple of inches and here is a link that allows you to listen to the sounds of a number of fountains.