We live in a three apartment complex. We have two bathrooms. One has a bathtub and shower combo and the other is just a Shower. In the one with just the shower there is water standing about 3" below the floor level of shower. To me that shouldn't be. I have been told it is because of a p trap that is to keep the gases from coming back in from the sewer. I am trying to figure out why would they put a p trap in the shower and/or tub instead of a direct flow down to the main drain? I have done a lot of plumbing and have never put a p trap in a tub and/or shower line. Am I wrong in my way of thinking? Also we live on the first floor. Also we live in Texas.

The water you see is normal. It's the trap seal.
I am trying to figure out why would they put a p trap in the shower and/or tub instead of a direct flow down to the main drain? I have done a lot of plumbing and have never put a p trap in a tub and/or shower line.
Well Pops, I don't know how they do plumbing inTexas , but in the rest of the world we like to keep sewer gas in the sewer and not in our homes. Every state and Canada MANDATES that every fixture MUST have a trap and a vent. How about vents? Do you feel the same way about them also?
Every one of the fixtures you installed without a trap left the homeowners family with a direct open connection between their house and the city sewer. Sewer gas's harmful to your familys health and the methane content in sewer gas's explosive. My advice?:
Sell or dispose of your plumbing tools. You're a danger and a public menace when you use them Good luck and I hope you follow my advice. Tom

The water you see is normal. It's the trap seal.
Well Pops, I dunno how they do plumbing inTexas , but in the rest of the world we like to keep sewer gas in the sewer and not in our homes. Every state and Canada MANDATES that every fixture MUST have a trap and a vent. How bout vents? Do you feel the same way about them also?
Each and every one of the fixtures you installed without a trap left the homeowners family with a direct open connection between their house and the city sewer. Sewer gas's harmful to your familys health and the methane content in sewer gas's explosive. My advice?:
Sell or dispose of your plumbing tools. You're a danger and a public menace when you use them Good luck and I hope you follow my advice. Tom
Thanks speedball1. I knew that vents were used to help vent the gases out. I just was never aware that you needed traps at the tubs and showers. I did know that about the sinks in the kitchen and the bathrooms. I was not a plumber by profession. It just didn't make sense to me that the line couldn't be run direct and have a vent in the system.

I knew that vents were used to help vent the gases out.
Not quite true. Vent systems are there to relieve the suction caused by water draining through the drain line. This suction could pull the trap seal right out if vents were not in place. House vents do not "exhaust" anything out, they pull air into the drainage system. Sorry If I got a little testy with you but I tend to get ve4ry pissy when proper plumbing practice isn't followed. You have a great day, Tom

Not quite true. Vent systems are there to relieve the suction caused by water draining through the drain line. This suction could pull the trap seal right out if vents were not in place. House vents do not "exhaust" anything out, they pull air into the drainage system. Sorry If I got a little testy with you but I tend to get ve4ry pissy when proper plumbing practice isn't followed. You have a great day, Tom

Apology accepted. I guess I need to be educated a little more. Now the question I have is why is the water in the drain 3"below the shower floor? I can see the reason for water in the p trap but shouldn't the trap be downline some so as not to leave water standing right at the shower floor even in the drain? That is the concern that I have.

Hey papa, take a full bottle of pop or water and turn it upside down with not cap, that's what your drains would do if there were no vent to allow air inside the drain pipe. Every fixture needs a trap and you can see water in most showers. You won't see the water in a sink or tub just because of the way they are constructed, but the trap is there.