In much of Mexico, it is common to notice a sign in the toilets of public spaces asking you to not flush toilet paper but to place it in the trash bin. This often brings the hushed question from visitors upon their return to the facilities, as to why the toilet paper should be discarded in the trash rather than flushed. While perhaps the most unpleasing conversation over dinner, let’s answer this question here and hopefully you won’t be asking it over your ribeye and asparagus with hollandaise sauce at Rincon del Bife Restaurante!
The answer to the question of whether to flush or not flush toilet paper can only be answered with a maybe. The problem is not a cultural issue or even the municipal sewer system in most cases, but likely the drainpipe between the toilet and the street drain connection. The difference can also lie in the system being used to treat the waste products, which is everything that is flushed down the toilet.
First, you should consider that many buildings and homes in Mexico are quite old. There are restaurants in Mexico City that are located in buildings that over 400 years old, twice the age of those in the United States. These older buildings predate the use of modern sewer systems. In these older buildings that were converted over to municipal sewer systems, they often used short sections of red clay pipes joined together for drainage, as the PVC pipe was centuries away. Over time, as the clay pipe aged, it became porous and rough on the interior and the joints between the sections would separate forming more places for paper to hang up and create a clog in the pipe. Another problem occurs when the pipes collapse altogether. And, you can add low water pressure to the mix as it may not be strong enough to push the paper that is clinging to the pipe away and into the more modern municipal sewer system.
But wait, there more to the movement of waste along the length of the drainpipe. The public establishment that you are visiting may have originally been a home for perhaps 4 or 5 people, but today has been converted to a restaurant that is used by perhaps 100 people or more on a typical day. The original pipes that were of a size able to accommodate the family can run into problems when there is a larger flow of waste. Also, if the pipe is not on a sufficient incline to allow for the increase in waste, it may become easily clogged and backup. And, if the pipe is too steep as in the case of a second story toilet, the liquid waste may flow too quickly down the pipe leaving the elements that are heavier or stuck on the walls of the pipe to create a clog. The rule of thumb is that the drainpipe should slope 1/4-inch per foot of length to promote proper movement of both liquid and solid waste.
If the establishment went to the huge expense to break up the rock or concrete flooring and install PVC pipe much of the problem might be avoided, but this is not always a viable solution, especially if the pipes go under other properties before attaching to the municipal sewer system. Even, then in some locales the drainage could still be problematic if the water pressure is unable to push the waste products sufficiently into the municipal system.
If the establishment is in one of the large metropolitan cities and is on a municipal sewer system and is using smooth interior piping such as PVC, the answer is normally yes, you may be able to flush the toilet paper as the modern municipal system can handle the paper from toilets. In the municipal system, the cellulose in the toilet paper is chemically treated to break it down and destroy it in the recycling process.
If the establishment is an older building, as much of Mexico’s finer restaurants are, they may not have access to the municipal sewer system and thus may be on a private septic tank. While it is possible that the bacteria in the septic may break down some or most of the cellulose in the paper, an excessive amount of toilet paper can become problematic. The septic tank becomes overloaded with the paper and is simply unable to break down the huge amount of cellulose.
And, this dear reader is why you need to respect the sign in the restaurant’s bathroom in order to avoid the embarrassing backup during your visit to the toilet.