YSK: Your dishwasher is far more energy / water efficient than you are at washing dishes. Running a dishwasher that is only 25% full will still use less water, on average, than hand washing those dishes. Save water, energy, and time by using your dishwasher instead of washing by hand.
from /r/YouShouldKnow
YSK：你的洗碗機比你洗碗時更節能/節水。在洗碗機只裝滿25%的情況下，其平均用水量仍比手洗餐具少。使用洗碗機而不是手洗，可以節約水、能源和時間。