Ask the Home Inspector: Can I Pour Grease Down the Drain?

Two weeks ago we took a small vacation from inspecting homes and spent some time at one of North Carolina’s beautiful beaches with a group of friends.  After frying 3 pounds of bacon one morning for a community breakfast, a fellow beachgoer asked why I was pouring the grease in a dish rather than down the drain.  Her comment prompted this blog.

You should never pour fats, oils, or grease down the drain because eventually the grease will cool and harden, causing it to stick to the pipes surfaces. Many people believe that running hot water can alleviate the problem, but that only moves the grease so far down the pipe.  It may take a while, but slowly and surely, grease will block up your entire pipe, leaving you with a drainage maintenance disaster on your hands.

A one-time accidental pour does not necessarily create a clog, and you can pour a quart of boiling water down the pipes in hopes to liquefy the grease and move it further down the pipe. Remember though, anytime you introduce grease into the system, the likelihood of a problem intensifies, so it should never be a habit to introduce grease into the plumbing system. You may find yourself with an expensive repair bill to replace the pipes!


The problem can be further amplified if you are on a septic system. The main reason fats, oils, and grease can be troublesome, is that it is not water-soluble. It will eventually separate from the water. Grease is lighter than water, so it floats to the top. If not treated, grease molecules combine to form a hard grease layer. Or, worse yet, the grease combines with other materials such as soap residue, paper, and solids. When this happens in a septic tank, a very hard crust can form on the surface of the water in the tank.  If left untreated, it could flow out to the drainfield and cause drainfield backups. In a plumbing system, grease traps, drain lines, and sewers can become clogged and flow is stopped.

So what should you do with the grease? Collect liquid grease to be recycled or let it harden and then throw it away in the trash. Wipe all pans clean with a paper towel and rinse the pan with cold water. Food scraps should go in the garbage can, not the garbage disposal.

I hope you enjoyed this edition of Ask the Home Inspector. Please feel free to submit questions to us anytime to be featured on an upcoming blog!

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