Good idea, poor execution! The lid seal works, *until* you want to boil the water in both chambers, ie a kettle full. After you've done that for the first time, any water in the top chamber spills when you pour out boiled water from the bottom one. You can avoid this by only putting in as much water as you want to boil ... but you can do that with any kettle, which makes this hulking great thing redundant. It's top heavy and awkward. Yes, it boils fast, but the moment my husband's back is turned, I'm going to replace it with a smaller, single-chamber, non leaking kettle. And measure my water.