I just bought an old farmhouse (really good deal) an am going through all the repairs that need to be done and now have a puzzle.
When a large amount of water is flushed down the pipes (i.e. bathtub emptying) the basement fills with sewer gas. Found a clean-out cover rusted out (and now fixed) but still having the gas odor.
I think that when the waste water enters the tank, the gas gets pushed back. After the fix it has dropped noticeably, but it appears it has now been directed to the tank vent.
There's still some gas in the basement, and a fairly good stench from the septic vent, have I been living in the city so long to forget that this is normal?
Check to be sure that the vent pipe for the bathtub is also clear. It sou
nds like there is a problem with the venting system. The toilet may be cau
sing the same problem except that there is not a large enough volume for a
long enough period of time. Verify that the vent pipes are clear all the w
ay to the roof.
Does the tank have its own vent - separate from the roof-top
plumbing vent ? < all three homes that I've owned were septic
systems - with only the roof-top plumbing vent >
What is the elevation of the septic tank inlet pipe - when compared
to the cellar floor ? < all three of mine were about 5 feet above
the basement floor > The tank on my present home is only about 8
inches below surface - earlier homes were about 12-14 inches down.
I've never had any problems - never worried much about them ..
Maybe you'd want to pump out the tank and have it inspected -
- the baffle on the outlet is important. The consistancy of the
septic waste might tell you something also - the tank-pumping guy
usually knows a thing or two. Good luck.
Can't unless there's a line w/o a trap or a trap of a long-deserted or
unused trap is empty; if the house has been unlived-in for a while it's
quite possible some have evaporated enough to leave a path if not
everything is being used.
We have a number of plumbing fixtures that are seldom used, so we
routinely flush those toilets and run water in the tubs and sinks to
make sure the traps don't run dry. We're not on a septic system, but
all traps, regardless, can potentially run dry if not used.
~~ If there's a nit to pick, some nitwit will pick it. ~~
Yep, that's the first thing to check. Find every drain and dump a small
bucket of water down it. If any of the traps are dried out, the
plumbing stack vent will not have any effect on the situation he
describes. It really doesn't take all that long for a trap to dry out if
it's not constantly doing its job.
I'd assume since house is old the vent is in the waste line leaving the
house, not a vented tank (I guess some are done that way, never seen it
though and spent >50 yr in houses on septic systems).
I'd suspect besides the other note on dry traps possibly there's a
basement floor drain or unused washer connection or something down there
Unless the exit vent is blocked or there's a leak in a vent itself,
other than coming back through a dry trap there really just isn't a path
for gas back into house...it would take quite a lot of pressure to force
it back through a full trap.
What do you mean by the "septic vent"? Normally, your main drain line
should have a vent pipe that runs all the way up to the roof. There should
also be individual vents for each fixture (sinks, toilet, tub, etc.).
Some older homes may not have vents for each fixture. This creates a vacuum
in the drain line when you dump water down the drain (like the glug glug
you get when pouring water out of a bottle). For something like a sink
there's usually still air space in the drain pipe that allows some venting.
But draining a bathtub may completely fill the drain pipe, so it will be
trying to suck air from any place it can in the system.
If the vent extends through the roof, but you're smelling gas in the
basement, you have a leak somewhere. If no water is leaking out anywhere,
it's probably a leaky vent pipe.
You might try applying some really soapy water around all the joints in the
pipe and see if the soap bubbles up anywhere when you drain the bathtub.
Though in theory, it should be sucking the soap inward and not exhausting
Assuming you have a roof vent, you may want to check that it is not clogged
with a bird nest or something. I recommend getting a cap for the top that
allows air to enter and gasses to escape, but keeps out the birds
(available at any home center).
On Sunday, March 26, 2017 at 12:11:55 PM UTC-4, HerHusband wrote:
Older homes I've seen here, built 1950 and earlier, don't have
a main vent that runs out the roof. They have one on the
sewer line, near ground level, where it exits the house. Then
they have vents for bathrooms and such that do extend out
Interesting, I haven't seen that (in my very limited experience).
My in-laws house is about 100 years old. They had a single main roof vent
(only 2 inches for the whole system), but none of the individual fixtures
had any vents at all.
Not normal. If you haven't had the septic tank pumped out, it may be backing up.
You should have it pumped out AND have it inspected to make sure it is in good
working order. It's possible you may need a new septic tank AND a new drain field.
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