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LCR Aug-07



Toilet Paper... Do you know Origami?

The debate among friends in high school was whether the toilet paper should be scrunched or folded when used.  But here in Mexico, the debate includes whether or not the toilet paper should even be discarded into the toilet at all.  

Yes, this is a dirty topic however, it is a common to question about whether or not, one can throw the toilet paper into the toilet and the answer is a definite maybe.

Getting back to the question at hand (so to speak), to answer we must understand the system being used to treat the waste products.  And to be clear, when I say, “waste” or “black water” I am referring to everything that you flush down your toilet.  If you have a municipal sewer system, yes you can flush the paper down the toilet since the municipal system can handle the paper from the toilets.  And if I have a private septic tank on your property the same answer can be true since the bacteria in the septic tank can help break down the cellulose in the paper nevertheless, an excessive amount of toilet paper can be a problem by overloading the tank and slowing down the bacterial activity in the septic tank.  Hopefully the septic tank is healthy and large enough to handle the volume of material that needs to be treated. 

Now we should know that only the villages and towns of the Lake Chapala (i.e. Chapala, Jocotepec, Ajijic, San Antonio Tlayacapan, San Juan Cosala, etc) have municipal wastewater treatment plants to handle the “black water” from the toilets etc in their respective communities.  However, it is common to see in the village businesses, a sign in the bathroom that will tell you not to throw toilet paper down the toilet.  The problem is not the municipal sewer system but likely the drainpipe between the toilet and the street drain connection. 

The typical problem is the type of pipe that has been used.  Traditionally, the drains from the house to the street were short sections of red clay pipes joined together.  The clay pipes over time become porous and rough on the interior surface and the joints between the sections of the pipes open up or due to low strength, the sidewalls of the clay pipes slowly collapse.  The combination of these three deleterious conditions, do not promote the easy flow of toilet paper along the sections of pipe and the toilet paper or waste product can become hung up on the joints, breaks or rough surfaces.  Once stopped along the sidewall, they become the collection point for more and more toilet paper and waste, which eventually clogs the pipes and stops the flow of waste.  

More modern drains systems use plastic piping (typically PVC) for the drainage of waste.  These plastic pipe systems tend not to have the hang up points along the length of pipe for the toilet paper and hence, less chance for a clog forming in the drain, therefore more favorable to toilet paper movement along the length of the drain pipe.  

But that is not all the factors that affect the movement of “waste” along the length of the drainpipe.  The slope or inclination of the pipe affects the movement of the waste.  If the pipe is too steep the waste flows quickly down the pipe however, elements of the waste could become “stuck” to the side of the pipe and become a point for the future toilet paper to hang up on the sides of the pipe, helping to form larger and larger clogs that eventually plug the drainpipe.  Ideally, the drainpipe is sloped or inclined approximately 2% or ¼ inch per foot of length, to keep the waste in the pipe, wet and among liquid to lubricate and promote the slow but constant movement of waste material along the length of the pipe.  

So as your are about to throw the paper into the toilet, use your x-ray vision and determine what type of pipes are underground and how they were installed.  Easy if you are Superman however, maybe we just need to respect the sign in the restaurant’s bathroom.  

The Lake Chapala Review is a free monthly English publication available at Lake Chapala.  It is publicized on the 15th day of every month.

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All material on this web site is Copyright© J. Brad Grieve, P.Eng. MBA
Last modified: November 04, 2008