We use glass water bottles. Changing the water every 2 days. We like the glass better than the plastic because we are able to sanitize them completely with boiling water every couple weeks. They are also dishwasher safe. With the small opening, I do not recommend using the dishwasher as the only way to clean your bottles. A bottle brush works great for the weekly cleans. Make sure to wash the tube with a twisted pipe cleaner. Don't forget to wash the floater really well too!
As many of you know finding a bottle that doesn't leak is important. The type we discovered we like best was Critter Ware. They have 10 oz and 26 oz glass water bottles to choose from. Due to the size of my mischief, I use four 26 oz and two 10 oz bottles. They come with a handy floater inside to keep track of the water level. They also have great hardware to attach to the cage. The bottle has a completely flat side that makes it convenient to use either inside the cage or on the outside. We found the larger bottles do stretch the 1/2 bars on our DCN, but they will fit if in the middle of the vertical lines. The tube is able to twist around to be in the correct direction needed once the lid is put on tight. At first when we put the bottles up, we get a few drops of water. Don't worry, this is just creating the vacuum to prevent further leaks. The washer in the bottle works really well at keeping them from leaking after the vacuum is created. I know this because I forgot to put it in once! What a wet mess! Luckily, it was right after I cleaned cages.
***When we switched to the larger bottles, one of our boys, OCRA Beast, didn't like the larger tube of the bigger bottle. To solve this, he simply pushes on the ball with his hand to fill it up, then drinks it from his hand.
Overall, I would rate the Critter Ware glass water bottles 5 out of 5 stars!
(Links may not be the current cheapest around but will give you an idea of what we are talking about. All of the Amazon Smile links can benefit Best Friends Rodent Rescue. It is simple to set up - follow directions at the top of the Amazon for 'Amazon Smile' then find their non profit charity. Once you set it up, save a bookmark for every time you use Amazon)