Hi my family and I almost 3 years ago moved into a 1960's old villa type home and for the last two summers we've noticed this bad smell, mostly under house at the back but rarely but sometimes can be smelt from inside in kitchen and back hallway(as we have 3 in house)my story is kind of similar to one I read on here so I will try that line thing that was suggested but I am just wondering could it be any other reason,
At first because the smell is like animal dropping more so of a dog or cat at times or sometimes just smells like the human kind and we don't even own a pet besides two hamsters but there are always stray cats around, but at first that's what we thought the smell was so we ignored it.. but then last summer we had a family get together and we hadn't smelt that smell in a couple of days then while everyone towards dinner time was sitting in the nice heat eating our BBQ on the deck that smell came and man was it potent, everyone tried to be polite and they kept eating but it even got too much for me I could taste it in my mouth and it's embarrassing to think they might of too :( then in the other seasons it's comes and goes and winter we don't smell at all but in summer it's here constantly and it always seems it's when we have more people in our house visiting(that could be just me paranoid) then it happened last summer and now it's happening again, I thought it would go a away as I thought maybe because no one lived here for a while that it was just a lingering smell that would fade over time but it's not and I'm at wits end... please please please help us I am worrying that it could be something that could harm me or my children overtime... please :)

And sorry excuse a couple minor typo's it's suppose to be it's under the house "and" rarely not "but" it can also be smelt in kitchen and back hallway... and I will try the "Lime" thing not "Line" sorry :)

Do you own or rent? What is the foundation? Is there a cellar or crawlspace? Where is this, what state? Are you on town sewer or septic?

Do you think you can distinguish between dead animal smell, and sewage?

We rent and I live in NZ it's a suburban area and I believe we are on town sewer system as is all the houses around the area, there is no cellar but there is crawl space enough under the house and yes it smells more sewage like then and foul droppings sometimes animal sometimes human or flatulence, I have smelt something dead and I don't think it smells the same.. does this help u help me??

If the smell is really bad then the landlord should send someone to go into the crawl space.
99/100 times it's a broken sewer pipe or a dead animal.
Dead animals stop smelling after a while, but how long depends on their size and how wet the area is.
If it's been a year or more, I'd go with sewage, and that's a health hazard. It's the landlord's job! If you want to crawl in there to find it, feel free.