By now, most people are familiar with what an “P” trap is under a sink or other fixture, even though it may also be called a “J” trap or even a “U” trap.

It’s in the pipe under the sink that rises up, like a J.  If it is filled with water, as it is supposed to be, it prevents sewer and other odors from being released into the restroom.  Also, we should know that if the water has evaporated or the trap is not working correctly, there is the possibility that gas could be released, which can pose a serious health risk.

However, many people may not be that familiar with something else that is part of their restroom plumbing system, and that is a vent, more formally known as a drain-waste-vent-system (DWV). And even if they have heard the term before, they may not know exactly why a restroom fixture has or needs a vent at all.

Whenever a tub, toilet, urinal, sink, or floor drain is installed in a facility, a plumbing vent must be installed on the drain for it to work correctly. Mostly what it does is direct sewer gasses from the pipes to an outdoor vent and allows air to enter the plumbing system. This allows wastewater to flow freely.  However, if there is no vent – or if the vent is blocked or becomes defective in some way – some of the following problems may occur:

•    Water will drain slowly

•    The drain may make a gurgling sound as the water drains; this is one of the most common problems and a tip-off that something is wrong

•    Water in the trap siphons out.  If that happens, then sewer odors will likely be released.

The Plumbing Tree

We should also note that while each drain needs a vent, that does not mean each fixture has its own vent.  What we typically find in a restroom is that the drain pipes from sinks, toilets, drains, and urinals all come together at one point, connecting to a large central pipe.  Invariably this all happens behind the walls of the restroom. This is referred to as the “plumbing tree,”  which is regulated by plumbing codes.

That large pipe carries water and waste from these fixtures down to the sewer.  Connected to this large pipe is another pipe which exits through the roof or outside the facility, allowing sewer gasses to be released through the vent.

So now the question comes up, if installing waterless urinals, which use no water whatsoever, do they need to be vented?  The answer is yes.  The waterless urinal must also be connected to the plumbing tree.

Here’s why.

Even though the waterless urinal does not use water, we still want to make sure the urine drains properly through the drain connected at the base of the urinal. Further, for the most part, waterless urinals are cleaned like flush urinals. This means water may be used in the cleaning process.  It’s important to make sure any water used in cleaning flows through the drain, and for that, we need a vent.

For more information on plumbing, vending, and of course Waterless Urinals, contact a Waterless Co representative at 800-244-6364.