Oh God, how disgusting. I hate these large rodents and besides, I am very much afraid of them. If we had rats, then I would definitely not be able to sleep at night. When we had mice in our house, I almost went crazy. I was tense all the time, listened to any rustle and was terribly afraid that this creature would crawl into my bed at night. I can say with 100% certainty that you have sewage problems. Therefore, urgently first call the master to deal with the root cause. Here are the contacts of a trusted company https://pomplumbing.ca/back-to-base-building-and-new-installation/. And then it will be necessary to poison the rats themselves. Wish you luck.