If the "add water" light turns off, then you've found the issue. If not, check and see if your water tank is locked in properly. If it isn't, try taking it out and locking it back in.

Luckily, you don't have to just toss your Keurig just yet. There are a couple of different ways you can address scale buildup in your water tank and tubes, depending on how bad it is and where ...