The tank is just enough - at medium setting with aeration. If necessary, you may have to refill once. The adjustability of the beam is sufficient. By contrast, the Philips Sonicare sch proved to be too hard (bleeding gums despite Resilience), also by single shots impractical (and much more expensive). The Panasonic, however, provides ongoing impetus, as one is used to from other showers. If the manufacturer still wants to improve something, then: 1) slightly larger tank, 2) slightly smaller design.
