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Old 11-11-2011, 11:29 AM   #1
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full septic tank

I believe I understand how a septic tank and field works. But when the time comes to empty a septic...I picture it pretty much being like a bucket that's packed with mud - you dump water or more stuff into it, and it just sits on the top. And that could be bad news for the fields becuase solids could reach them.

We've been having some issues I won't go too far into - basically basement toilet is bubbling when someone uses water upstairs.

So if the tank is full in the way I describe above, it would make sense that as stuff hits the tank, it can't enter it or purge off as quickly - causing some backup issues at the lowest drain - my basement. That toilet then doesn't flush well for a bit - but later in the day, it will.

So I'm hopeful if I just get the tank emptied - my problems will stop. I'd simply put my home back to the beginning of the cycle.

Is this logical thinking or has anyone else experienced this?

Or - is the fact that I'm experiencing this basement toilet bubbling evidence of an even larger problem?


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Old 11-11-2011, 11:59 AM   #2
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If the tank is full, you can get back ups into the lowest fixture. When was the last time it was emptied? It should be emptied ~ every 5 years.


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Old 11-11-2011, 12:58 PM   #3
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The solids sink to the bottom. There may be some foam at the top but nothing to keep the liquid from flowing into the field. There shouldn't be much floating. A properly installed septic system really can't back up to the interior unless of course for some reason the field drain is blocked, but it shouldn't be. The field drain is lower than the home egress.

We pump ours every year, in fact they were just here yesterday. It just depends on the size of the system and how many are in the family as to how long you should wait between cleanings. Five years in some cases may be pushing it a little. In my thinking five years would be the maximum time between cleanings.

I guess I should add that theoretically the things should take care of themselves but with today's bacteria-killing chemicals that find their way into the system it is easy to wound the process I suppose.
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Old 11-11-2011, 01:50 PM   #4
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First thing first, it definitely sounds like it is time, and very possibly past time to get your tanks pumped, as 47 and Bud have already suggested, so you need to schedule that ASAP, and plan to have it done regularly from that point forward. As for the content of your tanks, most of what goes in is liquid, and the bulk of the solids will break down over time, if your septic is working properly. Properly, in my opinion, is much harder to achieve now than in the past, due to the volume of soap, tooth paste, mouth wash, toilet cleaner, etc. that goes down the drain, all of which kill bacteria, which is good for us, but not for a septic system. This is one of the reasons that "old timers" will often say that a proper septic system does not need to be pumped, which was very likely correct when baths were still once a week, and toilet cleaners, etc. were not as prevalent, but it's not good advice today. Also, by the way, when you are on a septic system, kitchen scraps belong in the garbage or compost pile, not down the garbage disposer. As for your basement toilet, the person who pumps your septic tank(s) can very possibly provide an educated guess as to whether the amount of sludge at the top of the tank(s) may be causing the slow flow from the tank to the field, but as a matter of good measure, you may want to buy or rent a hand snake, and use it down the roof vent of this particular line, in the event that you do have a partially clogged line.
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Old 11-11-2011, 02:51 PM   #5
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The septic tank has sludge (mud-like solid) at the bottom, foam/scum/grease on top, and water in the middle. The level of the top of the water should be about 9 inches below the underside of the tank lid.

There should be baffles or elbows at the inlet and outlet so the scum and sludge don't exit the tank and go down to the leach field. Only the water should exit, gallon for gallon, as new sewage enters from the house. If you wait too many years before pumping then the layer of sludge at the bottom and/or the layer of scum at the top will get so thick that these materials do exit the tank and damage the leach field.

If the leach field is damaged (grease soaked or clogged with roots) then the entire system can back up into toilets and drains starting with those on the lowest level of the house (or overflow onto the lawn if you took the lid off the septic tank).
The good conscientious technician or serviceperson will carry extra oils and lubricants in case the new pump did not come with oil or the oil was accidentally spilled, so the service call can be completed without an extra visit.

Last edited by AllanJ; 11-11-2011 at 02:57 PM.
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Old 11-11-2011, 05:15 PM   #6
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It is not necessary to rely on theoretical tank pumping schedules such as every year or every five years. It is quite simple to check your tank. You open up the lid, insert a (disposable) stick wrapped in a rag, and push it to the bottom of the tank. Tanks are typically 4 or 5 feet deep, so you will need a stick that is at least that long. Withdraw the stick, check the rag. If there is less than 6-9 inches of sludge at the bottom, no need to pump. Any more than that, time to pump.

As for dumping detergents, chemicals, and solid waste down the drain, that is entirely within your control. At our house, we compost all of our food scraps. We NEVER dump chemicals into the tank, that means no Draino, no bleach etc. Minimal amount of laundry detergent is used, low to zero phosphate. Every year I check the tank, and there is less than 2 inches of sludge at the bottom (this is after 15 years of use), and virtually no scum at the top. I have not pumped in 15 years, as I say, it is only necessary to pump when your solids have built up, and this will not happen if you are careful about how you treat your system.
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Old 11-21-2011, 09:52 AM   #7
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My guess is that you're barking up the wrong tree with blaming your septic system. Still an excellent idea to have it pumped if you've not done that within the last few years (make sure to be there and chat up the person doing the pumping... you'll usually be able to get them to do a very quick visual inspection to see if they see any major issues - such as a baffle broken/missing or a very large crack in the tank.).

I'm thinking your bubbling issue is a clogged vent pipe. Clogs can be caused by a [bird/small animal/swarm of bees] building a nest in the vent pipe that extends through your roof, or an incorrectly installed vent pipe that isn't sloped correctly and fills up with standing water.


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