I am renting a modular home built on a slab with septic. Do you think the septic tank needs cleaned if I have a bad sewage smell only when it rains real hard? Since I am renting I have no idea when the last time the septic was cleaned and I am having a hard time getting the landlord to do any work or upkeep on the home.

There is a low atmospheric pressure on rainy days keeping, and pushing, sewer gases close to the ground. That's why you smell sewer around your house.

I'm sorry, I meant the sewage smell is inside my house not around it.

Look in the attic. Any open pipes up there? Let me know, tom

I am also having this problem. I live in a doublewide, the septic tank is brand new just installed in August 2010. But when it rains the inside of my house smells like pure sewage. It's unbearable! I told the landlord and his fix was to vent the pipes outside. Well, there is a stink pipe so I don't see how another vent could be the issue. He is wanted to sell us the place and we'd like to buy it. But quite frankly I'm not buying anything where I can't enjoy a rainy day without my nose being full of the smell of poop.