Ugly, grimy, black lines on carpet that are from filtration soil

How to Remove Filtration Soil and Prevent It Forever

Dark, shadowy, dirty lines on the carpet along baseboards, under doors and draperies, along the edges, and in the crevices of carpeted stairs are all visible signs of an aggravating, disgusting problem called filtration soil. Basically, it’s visual evidence that the air in your home is killing your carpet.


Ugly, grimy, black lines on carpet that are from filtration soil

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Your carpet is the biggest filter in your home. Just like your furnace and air conditioning filter that filters out airborne soils that pass through it, your carpet does the same thing.

Filtration soil comes from airborne pollutants passing through the carpet as the air is drawn through the crack between the carpet and the baseboard, around the drapes or under a closed door. It’s an accumulation of soot from dirty ducts, smoke from candles and the fireplace; tobacco, kitchen grease from the oven and cooktop; smog, auto emissions and pollutants from outdoors.

A home’s HVAC (heating, ventilation and air conditioning) system is designed to filter out airborne soil, trapping it in the filter. But once the filter is full, the system will send the air pollutants back into the house through the ducts where all of that icky mess gets lodged into corners and crevices. And if that’s not enough, filtration soil makes your house smell bad.

Normal vacuuming is no match for removing filtration soil. And neither are the best carpet spot removers. Filtration soil is greasy and sticky.

A severe case of filtration soil may require the services of a professional carpet cleaner who specializes in this unique problem. However, it is possible to effectively do it yourself provided your soil problem is not severe.



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How to remove filtration soil yourself

  • Using the vacuum crevice tool, vigorously vacuum the areas suffering with filtration soil to remove any loose debris and dust from the crevices.
  • Use a specific cleaning product for this kind of soil like Prochem Filter Out, specially formulated to remove filtration soil lines, soot and other electrically-charged particles. Apply it undiluted so that it saturates the fibers in the stained areas. Allow to sit for 3 to 5 minutes.
  • Scrub the lines of filtration soil with a good, strong brush that can get down into the crevices.
  • Extract completely using hot water or All Fiber Rinse—not absolutely necessary, but an excellent product that will assure a good, clean rinse. Use a wet dry vacuum to do this if you have one available, or blot well with a clean white cloth.
  • Repeat as needed depending on the severity of the problem

How to prevent filtration soil

  • Change the filter(s) on your HVAC system once every three months without fail.
  • Thoroughly clean the filter in the range hood, weekly.
  • Use the range hood fan and vent every time you use the oven or cooktop. You want all of that smoke, cooking oil and airborne residue to leave the house immediately.
  • Keep doors and windows closed if you live on a busy street or in an area with a lot of pollutants.
  • Make your home a smoke-free zone. All smoking should be taken outdoors and away from open windows and doors.
  • As lovely as candles and aromatherapy can be, these can contribute to a filtration soil problem. Switch to flameless LED candles, which create a lovely, realistic ambience. Some even have fragrance.
  • If you use a fireplace make sure the system is clean and the pollutants it creates are being properly removed from the house. Clean the chimney and filter (if any) regularly as well.


My own filthy filter wake-up call prompted me to get online to do some research. That’s how I found FilterEasy, a company that delivers the exact filter we need, just when we need to change it—at a comparable cost of the very same filter at the home improvement center store near our home. Wow! What a great service for those of us who need reminders. I don’t have to think about when to replace the furnace filter.

I set up an account online, identified the exact filter we need (they’re listed by size—including custom sizes if the filter you need is not standard) and the frequency of delivery, which took all of about five minutes. Now I can forget because I’ve put FilterEasy in charge of remembering.

We received our first shipment. Having that sizable box show up at the door was the reminder we needed to replace the filter—right then. Done.

You can probably beat the FilterEasy price if you buy filters when they’re on sale and are diligent in sticking to your own rigid maintenance schedule. For some of us, a subscription plan with FilterEasy is a real bargain given the high cost of failure to stay on top of this important home maintenance issue.

The folks at FilterEasy are offering Everyday Cheapskate readers their first set of filters free (you’ll just pay shipping) when you use this Link. Of course you can cancel or make changes to your subscription any time.

No carpet? You’re not immune to filtration soil

If you have no carpet, don’t think you’re off the hook when it comes to filtration soiling. Sure you won’t have black lines on carpet, but that sticky, black residue is going to find its way to upholstered furniture, hard surface flooring, draperies, blinds, windows and so on. More than that, filtration soil makes your house, well…stink!

Do what you must to get rid of all filtration soil in your home, then take the easy steps to prevent it, forever!

First published: 6-27-16; Revised & Updated 7-26-19

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2 replies
  1. Cynthia Van Horn says:

    I had this happen in 2000 in a home that was built in 1997 (way before the internet could give some ideas on what was occurring); my problem was the HVAC units. They were releasing insulation particles back into the home (most HVAC units have heat sealed insulation) and because the home was so “airtight” they had nowhere to go. We went through 3 months of checking soil, treadmill (yes, treadmill), did I run the car in the garage, did I burn candles (no), was it mold, I live in the country and even burning of trash, tires etc. were questioned (which is not allowed here) before they found the problem. If you ran your hand down the insulation of the unit, it was like soot. You could count the studs in the ceiling in most rooms from where it adhered. A pillow sham that looked fine but the inside pillow had black markings in the shape of the pillow. Dining room chair backs had a faint black line and the carpet was a mess. My family owned a dry cleaners at the time and nothing we did could get the pillows and draperies back to normal. Needless to say, it was a learning experience. Duct work was replaced as well as the inside units. Painting everything again, replacing carpet and most bedding and fabric chairs.


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