Rats live in sewers and can follow the food in pipes up to your toilet. Keep your kitchen sink rinsed clean and use garbage disposals as little as possible.Rinse out your kitchen sink once or twice a month.Use 1 cup of bleach (an alternative to using bleach, 1 cup of baking soda followed by 1 cup of vinegar) and rinse with boiling water.Never throw grease down the drain.Keep your toilet lid down when not in use.If you find a rat in your toilet, flush it! (hint: squirt a little dishwashing liquid under the lid into the bowl, wait a couple of minutes then flush.
Sometimes they crawl in through ventilation pipes on the roof, other times they swim in from the sewers and sneak in from cracks in the line. Most toilets trap enough water in the connecting pipe to discourage the rats from coming on in. However, in unused guest bathrooms and abandoned houses, for example, that water can evaporate. "You take any house in the city of Austin and let the water in the toilet dry up and you will have rats in the house," Grand said.
Rats took over a Lakeway house while the owners were gone for six months, he said. About a half dozen rats climbed in through the plumbing system and enjoyed a brief dream vacation of their own. They sampled all the food in the house, chewed on the Persian rugs, and destroyed thousands of dollars of furniture. "When I walked in, the house had a strong rat urine smell," Grand said. "Six or seven rats in your house is mayhem."
Hill was once called out to a newly built hospital with a rat problem. "They were going straight up through four stories of piping and getting in."