The average dishwasher uses about the amount of water you'd use for 1-2 minutes of shower time. Newer models use around 9 liters per cycle, older ones and non-e

The average dishwasher uses about the amount of water you'd use for 1-2 minutes of shower time. Newer models use around 9 liters per cycle, older ones and non-eco modes often 15 liters, and really old ones often 25 liters. A typical shower outputs 5-10 liters per minute. The water savings with eco-programs compared to "normal" programs is in the range of 10 seconds to 1 minute worth of shower time, if I remember correctly. If you want to conserve water use, there are a lot better ways to do so than running a dishwasher in eco mode. (Washing dishes by hand uses more water on average than even an old dishwasher). Then, the terminology of "waste" is a bit problematic I think. The dishwater will usually output the spent water into some kind of sewer system in most places, and at some point this water usually gets cleaned and put back into circulation pretty much straight away. If not, it usually reaches nature again eventually. It's not like it became so toxic it needs to be stored safely for millennia. That doesn't mean we shouldn't be mindful, of course, especially when there are current (regional) shortages. Energy consumption (mainly to heat water) is a different matter. Energy consumption is the real environmental cost, not water consumption, as water is basically renewable, but energy is often produced from non-renewable sources and has secondary effects such as carbon emissions, which in turn effect climate change and in turn regional water availability. But even then again, reducing shower time by a minute, or water temperature, will have a greater impact on energy consumption than running a dishwasher in eco mode (on average).