My husband owns a Chinese restaurant. Most of the foods are cooked in some kind of oil. If it isn’t canola oil, it’s hot oil or a garlic sauce. The liquids remaining in our woks are poured down the sink for disposal. We hadn’t had a problem with that method until about a year ago. The sinks stopped flowing properly and they were emitting a horrendous smell. We were constantly pouring drain cleaner down to try to get it flowing and smell better. After several unsuccessful attempts and lots of money down the drain, we finally got ourselves grease trap systems and they have made things so much easier.