Accept no mechanical substitutes to the tried and true P-trap
DEAR JULIE: Boy, oh boy, you sure know how to stir the pot! You put your finger on a beef I have about plumbing devices and code officials. Let's open the discussion with the fact that I've been a master plumber for over 30 years.
Let's go quickly back in time to just after the American Civil War. Sometime between the war and the 1880s, the medical community came to a consensus about the connection between bacteria and diseases. Plumbing standards rapidly advanced and, believe it or not, plumbers back then were often more highly regarded than physicians when it came to protecting the health of the general public.
That said, you never want to underestimate what can happen to you or your family if a plumbing drain system malfunctions or if you have a polluted water supply system. Entire books have been devoted to these topics.
Well over a century ago, it was quickly discovered you could completely stop vermin and bacteria from spreading into your home with a simple water seal under each plumbing fixture. They used to come in two styles: the S-trap and P-trap. They got the names because the shape of the drain pipes look like those letters in the English alphabet.
I have huge issues with mechanical plumbing drain and vent products that try to supplant the time-tested P-traps and traditional open vent lines that lead from fixtures up to the roof of your home. A mechanical device is one that has moving parts. Every mechanical device known to man has failed at one time or another. If you know of one that hasn't failed yet, just wait; it eventually will.
You don't want a mechanical trap under a fixture that will not close off properly. When the trap remains open, sewer gas or vermin can enter your home. What can cause a trap to stay open? If you've taken apart used P-traps and drain lines like I have, you'll quickly see biofilm, sludge, grease deposits, food chunks, gravel and so forth. These can all interfere with a mechanical membrane that's supposed to close tightly.
Then there's the occasional vermin in the drain line. You do realize that rats routinely patrol municipal sewers and think nothing of making a foray up your house building drain and then into a branch drain line. How long do you think it would take a rat to chew through a thin, flexible membrane only to stare you down at the sink stopper or basket strainer?
I've never sat in on meetings where building officials debate and discuss changes to the code. However, I have seen parts of the building code that make me shake my head. Some of the building code is not backed up with hard science. Apparently, many code officials have not seen as many old buildings I have; they tend to teach you that certain minimum standards must be always be adhered to.
You can't hope things are going to work. Hope is the emotion of last resort. You hope for something when you can't control the outcome. I can control the desired outcome in my plumbing system by using traditional P-traps and a real interconnected vent system that always supplies air to the pipes as water rushes down them.
The building code in your town is very possibly a hybrid version of a national model code. Building and plumbing codes can vary from state to state and city to city because local code officials can modify the model codes. I've also been told that some codes have provisions where a local inspector can approve an alternative material on his own. That's a very scary situation indeed.
Talk to any seasoned plumber and he'll tell you he's able to make a living because mechanical plumbing devices fail. Backflow preventer valves, regular valves of all types, pressure regulators, anything that has a moving part fails on a routine basis. Ask that same plumber about how well-designed and properly installed vent line systems work. I've never in my career had one fail. Never.
You can watch a pluming vent video and read past columns about P-traps showing how they work at http://www.AsktheBulider.com. Just type "vent pipe video" into the AsktheBuilder.com search engine.
(Want free home-improvement information? Go to http://www.AsktheBuilder.com and sign up for Tim's free newsletter. Have a question for Tim? Just click the Ask Tim link on any page of the website.)