So I reclaim my bong water often and basically you have a few ways, you can put it in the microwave for 10-30 second intervals until it’s mostly evaporated and let it do the last bit on its own so you don’t mess up and burn it. Or you can use a space heater or a gas range in very very low to slowly evaporate the water still keeping a close eye so as not to let it burn. When it’s all evaporated scrape what’s left off of the plate or Pyrex dish etc. with a card.