Reuse Water From Cooking Veggies

Like with the freshly boiled water from Wednesday, it seems a waste of power to just power it down the drain when we're done.

With pasta or potatoes, the water is often starchy and with veg such as broccoli, the water can be "discoloured" from the veg itself - so not really suitable for washing stuff.

So is there anything that can be done with it? I know some people use veg water as the liquid when making stock but what else?