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toilet flushing


I love stories about sewage in print.  As a water/wastewater guy, it is amusing to see sewer stories in the local papers and national news when they are about the “oddities” of operations.  One recent article talked about the impact of “flushable items” that should not go down the toilet.  “Flushable” wipes was the offender this time, but past discussion involved tampons, diapers and paper towels.  The reality is that NONE of these items should ever go down the toilet.  Those paper toilet seat covers are questionable as well.  Let’s see why. 

Sewer agencies have a very different view of what is flushable that tampon manufacturers, diaper manufacturers, paper towel and now flushable wipe makers.  Sewer agencies are responsible to insure that waste moves down the gravity pipes and through the lift station pumps without creating backups in the system.  The majority of material in a sewer system is water.  Followed by chopped up solids.  The design of the toilet involved two separate concepts.  One is simply creating the opportunity for a syphon to move waste when flushed but holding water when not.  It is a gravity principle based on partial pressures.  Simple stuff.  But toilets also tend to “chop up” material when the flushing action occurs.  The flush is violent and thin toilet paper and the soft solids in the toilet are easily shredded and blended into the water.  Think about your blender.  Soft stuff gets chopped up.  Enough mixing, it is all liquid.  As a result there is very limited opportunity for either thin toilet paper or most solids to plug up a toilet. 

But people don’t like thin toilet paper.  So we have manufactures making toilet paper with cotton fibers in it to make the paper soft.  And people like the “high quality” paper towels that upscale restaurants use.  Unfortunately too many people use those high end paper towels on the toilet seat, so down they go.  Wipes are reinforced paper also.  Fibers make them strong enough to, well wipe.  Tampons are notorious as absorbant fibers.  The key in each case is the fibers.  Fibers are not chopped up during a flush because the toilet flush is not designed to shed cloth.  As a result two things happen.  First, the fibers then to stay together as a mass.  Grease and other materials in the sewer system will stick to eh fibers making an even larger glob of material.  A recent YouTube photos showed a 15 ton grease ball in a large sewer system.  Grease and fiberous materials in the sewer system – you don’t want that to plug up your interceptor.

The other problem is lift stations.  The pumps at lift stations are designed to pass a 2.5 in ball, but not a bunch of strings.  As a result the fibers get stretched out, and wind around the pump impeller rendering it useless.  Or the material may mat in the impeller preventing the pump from pumping water.  One of the most common lift station problems is fiberous material winding around impeller shafts that burn out pumps.  Pumps cost thousands of dollars to repair or replace, so this is money from the ratepayers’ pockets.  One of my clients had the restaurant problem.  The lift station impellers would completely clog every 3 days.  The lift station would nearly overflow before the pumps were removed, the guys would open up the pump, and dig out the material.  Obviously fiberous paper and there were only two connections to the lift station.  The City ended up installing a $160,000 grinder system to grind up this material because the restaurant was unwilling to change their practice.  The major offender was women using the paper towels as seat covers.  The lines inside were a mess as well. 

The moral of the story is that toilet paper, water and body waste goes down the sewer.  Not napkins, feminine hygiene products, baby wipes or any fiberous paper material that feels soft, but won’t deteriorate, regardless what the manufacturer claims on the box.  These material do not degrade, the only create costly repairs, inconvenient and costly backups and a host of other problems for downstream users and the utility.  Put this material in the proper trash can. 

And see where else can you talk about this stuff, except when talking about sewage?

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