Every time you rinse a pan, pour off bacon grease, or run the dishwasher, a thin film of cooking oil, tallow, lard, and butter residue travels down the drain arm. While it's hot, it's liquid. The moment it hits the cooler sections of the drain — which in most Indianapolis homes happens within 3–4 feet of the sink — it crosses below 68°F and begins to solidify. This is FOG accumulation, and it's the cause of nearly every recurring kitchen drain problem we see.
Unlike a hair clog, grease doesn't sit in one place. It coats the entire interior circumference of the pipe in progressively thicker layers. On cast iron pipe — common in Indianapolis homes built before the 1970s — the rough interior surface acts like Velcro for lipids, giving FOG more surface area to bond. PVC, which replaced cast iron in newer construction, is smoother and accumulates grease more slowly, but it still accumulates. By the time you notice the drain running slow, the line is typically 50–70% narrowed.
Left long enough, FOG accumulation becomes a fatberg: a hardened, soap-like mass formed when free fatty acids in cooking grease undergo saponification — a chemical reaction with the calcium and minerals naturally present in Indianapolis water. Saponification converts liquid grease into something closer in consistency to candle wax or soft concrete. The U.S. EPA estimates that nearly half of all residential sewer blockages nationwide are caused by grease, and the Marion County Public Health Department enforces active FOG management requirements on all food service establishments for exactly this reason.
Why doesn't dish soap fix it? Dish soap temporarily emulsifies surface grease — it suspends the molecules in water so they can flow. But once that soapy water hits the cold pipe wall, the emulsion breaks, and the grease re-deposits. You're not removing FOG; you're redistributing it slightly further down the line. The fix is mechanical: a drum auger to break through the plug, or a hydro jetter with a grease cutter nozzle to scour the pipe wall back to bare material.