The Additional Capacity Reservoir Plus adds more than 70oz more to your Drinkwell Pet Fountain totaling over 1 gallon of storage. This is ideal for multiple cats or if you have dogs that are up to 50lbs.
Worth the Purchase by Nancy from Spring City, TN12/17/2013
Although I thought this extra reservoir would allow me to only have to fill their water once a week, with 5 cats I have to fill it about every 3rd day or so. But it is better than having to do it every day! It is easy to fill and replace back on the water dish. It gives them plenty of clean moving water that they love!