I have a small cottage (750 sq ft) and a septic (not sand mound). A plumber just installed all new plumbing. He added a sewer vent through the foundation to the outside of my house (where the toilet is)- it is 2 FEET tall. He said that vent will let air in to flush and a u shape pipe in the basement will hold water and prevent the sewer gas from coming back to the house and from going to the sewer vent (which is near a window). Two questions: Is it dangerous that the sewer gas has no place to go (the septic tank is sealed); also when I flush the toilet there is a noise in my tub. Hope you can understand my question - I am very concered and Thanks for any assistance.

Did the plumber install vents on every fixtire that has a trap. If he installed the tubs drain downstream of the toilet and didn't vent it you will hear a "guggle" each time the toilet's flused. It puzzles me that he would install a running trap, (the "U" shaped pipe) in your main drain if all the fixtures were trapped. A traps function is to contain sewer gas so it doesn't enter your home. By the adding the running trap ahead of the 2' tall vent he isolated the septic tank so it couldn't breathe or vent.
If he has installed the job according to code then both the running trap and the 2 foot outside vent are unnecessary and if he didn't then the trap and vent are there to compensate for shoddy work. If you wish to keep what's been installed then consider adding a septic vent cap to the septic tank.

I wish I could be more upbeat but you were correct to be concerned. It might pay you to get another plumber in to check his work. Good luck, Tom

Thanks Tom I think I better pay another plumber to come out. No vents are on any other fixtures - just one outside the house by the toilet. The tub's drain is downstream. He said the u shaped pipe - the running trap - was so the gases do not escape into the house or out of the vent (which is by the window). He said the vent outside was for air to come in to flush the toilet. I am concerned about where these gases will go if I have the septic sealed and its vent next to it sealed.

No licensed plumber would ever install unvented fixtures The correct thing to do is to remove the running trap and the Mickey Mouse vent and do the job correctly according to existing code. If he hadn't tied the tub oin downstream from the toilet you could have wet vented the tub through the lavatory drain. The way it sounds you will have to vent both the lavatory and the tub with separate vents. The good news is thar once you do the job correct the septic tank can breath and vent through the house vent system. I'm sorry to have to tell you this. Is there a pressing reason that he "jacklegged" the job instead of putting in in by code? Please let me know what happens now. Good luck, Tom

This is to Tom aka speedball1,

I hope you get this message. I can't express my gratitude for your assistance. I did as you suggested and paid a plumber that I was told was an expert on plumbing code. He agreed with you. He said the plumbing work was nice and would be okay if he removed the running trap and ran the vent through the roof. So with his word and yours I was able to talk with my plumber and did not back down. I even showed him your note. He went away and came back later that day and fixed everything - it looks great. I really appreciate you helping me - he might have bullied me if I didn't have your advise and the guy I later paid to come out. By the way he said he never runs the pipes that way but was going off the advise of another and thought he was doing me a favor. So Thanks Tom - I feel much safer!

Tom is off for a couple of days, but I will be sure to point him to your thank you note. I'm always thrilled to see posts like this one!