That rat is going to get a respiratory disease if kept like that for too long, especially with a water bowl. They do not fair well at all with higher humidity. They will get scabs on their tails for the increased moisture in the air, and they will also not be able to breathe.

And rats that don't breathe well, don't breed... Just get some tanks or convert a larger rubbermaid/sterilite/iris tub into a cage. What I did when I made a temp. cage for my lone male is, cut out the entire middle of the lid, except for the rim, replace it with 1/2" mesh, and either staple or zip-tie in place. Next, drill a large enough hole for the water bottle nozzle to fit through, and you are set. This works the same way as a tank, without the hassle of a tank. Has plenty of ventilation and they won't chew out. Just don't make any ventilation holes in the sides, there's no need for them. If you replace the entire lid with mesh(except for the rim that holds on the lid) you will be good to go. My hairless male did quite well in this until I found him a more suitable, open, wire cage(superpet).

Hope that cleared up a few things. Those drawer systems do not work well for anything other than storing inanimate objects. The rats will escape, and if they don't escape, they will probably die from a respiratory infection. There is no amount of holes you could drill in the front of that drawer that would be suitable for a rat's requirements. Just not probable.