All rodents carry disease.
Many of these diseases can be contracted just by you breathing the air in the infested areas.
Read up on Bubonic plague and Hantavirus.
Once they have become established in an area they will not just up and leave just because you remove the human food.
They will eat and chew on EVERYTHING.
They will eat the insulation off of electrical wiring, causing the place to burn down.
They chew up and make nests out of paper, cloth and mattresses, etc...
By now there are several generations of rats that have been born down there.
They will not easily give up their home.
All clutter MUST be removed and an exterminator brought in to successfully eliminate this health hazard.
Since you have access to a computer I suggest you and your other room mate do an online search on the hazards and solutions to eradicating this issue as soon as possible.

Sincerely

Hi.

One of my roommates is a hoarder. I knew this shortly after I moving into this shared house, but it hasn't been an issue as he only hoards in his room and in the basement. Nobody uses the basement except for laundry.

The basement is gross, and while it grossed me out at first I've never really cared because I never use it. But lately I have noticed (and so has another roommate) that there are rats in the basement. He hoards food in the basement, lots of boxes of cereal, crackers, chocolate, stuff rats love. Some of it is canned or on a table and they don't seem to touch that; I read that norway rats (basement rats) aren't good climbers. But it seems recently he put a ton of these food boxes on the ground or close to it so the rats can easily access it.

There are also a couple of old mattresses they are nesting under which I could probably throw away, but I don't know how much that would help when there is still food and they have boxes to hide in.

I don't know what to do. I don't want to move out because I love this home and rarely use the basement (the only place the rats are) so it's not really a big problem. But I still would like to get rid of the rats, I'd rather not hear scurrying and squealing when I do laundry and I don't want the population to increase.

I don't know how to tackle the problem because it's very hard to talk to him about it. Both myself and my roommate spoke to him on separate occasions about how his food is attracting rats, and on both occasions he was completely silent and said nothing in return. When I persisted for a response all he said was "I heard you." It's obvious he is emotional about this and I don't want to greatly upset him but I want to deal with the rats. I also don't know if it's even possible to get him to stop putting food in the basement.

I think if he at least put only canned or jarred food then at least the rats couldn't get it and he could still store food so it's sort of a compromise. I also thought about maybe asking if he could store his food in big metal containers so the rats can't get at it, that way he does not feel threatened and doesn't have to change his habit much, just take an extra step. Not sure which of these ideas is better/more realistic. He also stores newspapers and beer cans and other random stuff and that's fine with me because it's not food.

Any suggestions for how to approach this? Would really appreciate it.