2. Mix water and pasta sauce together in a bowl, then spread a 1/3 of it on the bottom of a 6-quart slow cooker. Add a double layer of noodles, breaking to fit if necessary.
Over the noodles, spread 1/3 of the ricotta cheese and 1/3 of the mozzarella cheese.
Add 1/3 of the meat mixture.
Repeat layers with sauce and noodles, then cheese and meat. End the layers with noodles and sauce topped with mozzarella cheese.
Sprinkle Parmesan on top.
3. Place the lid on the slow cooker and cook for 2 hours on high, or until noodles are tender.
4. When lasagna has finished cooking, turn the slow cooker off but keep the lid on. Let lasagna rest for 15 minutes.
This will make it easier to cut into nice squares.