The easiest way to spot a leaking tank for an active system is if the standing water level is below the outlet pipe invert.

Costs are going to vary, but a tank replacement here in NC that doesn't involve a lot of site hassles will run $1000-2000. You'll probably need a permit from your Health Dept. or other permitting agency first.

The tree is bad- period. Get rid of it. This fellow may just be drumming up business for his son.

The water level was definitely below the outlet pipe. I could see water coming in -- tank looked almost empty.

It's a gorgeous tree but I am resigned to it going. I'm expecting this to be a tree issue but there's no telling. We do a lot of rock farming here.

Plumber may be drumming up business for the son but I doubt it. But why I needed reality check with folks here. He's the local go-to guy, modest prices and very no frills. If the tank needs to be replaced his son is as good as anyone. Grew up in the business IYKWIM and it's a small town.

But still wondering if there's a way to test to see what it could be?

With the tank pumped out, you might be able to see any large cracks if any or roots penetrating the tank. Other than that it can be leaking out of pipe penetrations, if the water level is lower than that then it's leaking at the seam if a mid seam tank, around the blocks if it's an old block tank, or through small cracks that can't be seen.

Thanks piedmont. Again, corroborates what he said as a possibility.

What I wonder about ism that with the tank so empty, the sewer line from the house clogged up twice. Seems counter intuitive. Would that be due to lack of water in the tank?

Not in any way that I can think of, usually too much water in the tank can cause backup in the pipe. Sounds like a plumbing issue.

It is possible that your pipe to your tank is cracked, broken, has roots in it, etc. Unless there is someone in your town with a scope to actually inspect the line, you may be resigned to digging to locate the specific problem. If you don't replace the line, you may replace the tank and find yourself with the same problem.

i replaced my tank last year. $2800 in chicago burbs. but my probelms were obvious - the tank was visibly deteriorated at the output baffle and manhole lid, the lid fell in, and it would allow rain water to flood it, and flood the field.

if the only thing you see is low effluent level, and there are no problems in the field, then I would leave the tank alone for now.

get the pipe from the house fixed first (if needed) and resolve any internal plumbing issues first. my guess is the pipe from the house needs replacement (it could be kinked, have a low spot, broken, etc). replace it with schedule 40 PVC.

if after fixing your backup issues you continue to see low effluent in the tank, and are able to confirm the tank is leaking effluent into the ground - and this concerns you to the point that you want to dig it up and replace it -- then go for it. frankly I wouldn't touch it.

Doesn't the low level confirm there's a leak?

He saw water flowing into the tank, and the level is below the outlet. On an existing installation, is there some way that can happen other than a leak in the tank?

Over time, tree roots will draw out exceptional amounts of water. I have seen hand-dug wells dry because of willow tree roots.

If roots grew into the tank, that be visible.

Depending on the household size, don't most homes dump one hundred or more gallons per day into their septic tanks? I can't believe one or even several trees could go pull out that much liquid.

A single saltcedar can absorb 200 gallons of water per day. Large, established trees can absorb 50 to hundreds of gallons per day if there is a source readily available. If there are roots in the tank, that could be where the water is going.

if the only thing you see is low effluent level, and there are no problems in the field, then I would leave the tank alone for now.

Incorrect, leaking tanks are usually defined as failing systems since the leak is usually below soil that is considered suitable for treatment and/or near a seasonally high water table. That may not be the case in the OP's jurisdiction, but here such a tank must be replaced within 30 days.

I spoke to two septic people in addition to the plumber whose opinion hasn't been contradicted.

Everyone says the tank must be replaced.

The tree -- as you can see -- appears to be sitting directly on the tank and leaning over as a result. The wheelbarrow is over the inlet -- there's no more than 4 feet to the trunk and it's a 9-foot long tank. It is my favorite tree but it must go. Obviously, the PO is an idiot and I'd have ripped it out long ago if I'd known. No one needs this.

The plumbing/back up issue can be diagnosed if one of the septic guys actually shows up. He says he can power wash the line and do a camera inspection for about $300. It appears they have so much work they just pick and choose.

Failing that, my plumber has snaked the line, which is working normally. He can install access to that line outside, so it can be snaked in the future. I don't want to deal with 2 unknowns at once and there are other things going on.

No matter what I do, I know there will be a domino effect. Part of a retaining wall in front of an 80' hickory tree must come down so the tank can be removed/replaced. So that tree will need to come down within a year.

My gut is that my plumber knows what he's doing. His price for the whole job is reasonable as these things go and from what you guys have said -- about $3500 which includes the tree removal, tank replacement, wall removal/restoration, materials and labor. His son does the excavation and landscape end of things.

Plus, he's on board for the future and knows my issues here. And bless his heart he was here within 30 minutes when things backed up.

Am I missing anything?

regardless of what others think I will repeat my advice (having gone through this myself) -- there is no need to replace the tank unless/until there is a verified failure. you have other issues to deal with first and the tank may not even be leaking.

just to confirm - have the contractors inspected the output baffle & connections? did they inspect the field? what did they find? I don't see evidence of excavation at the output in your photo. can you reach down and take pictures of the inside of the tank? I did this with mine and found tree roots penetrating the ceiling. get the tank pumped and inspect the sides and floor? many other things to be done before tank replacement can be justified.

all your contractors have a financial incetive to sell you a new tank. do that as a last resort, and only after you verify a failure. don't do it just because someone "thinks" it might be leaking - make them prove it. way too much at stake for guesses.

skyjumper -- thanks for the heads up. There is not a normal amount of water in the tank. Not anything close to normal -- I've looked down there and it looks nearly empty. It hasn't been pumped in more than 5 years.

There is a tree growing on top of the tank, as you can see. We didn't see roots inside but the plumber believes the leak is near the bottom or in the area under the tree (which has grown a great deal in the past 2 years and has a root protruding from the ground directly over the tank as well. It's difficult to argue that the tank hasn't been compromised -- in fact I asked about that last summer when I noticed the root protrusion.

This is going to sound dumb because I haven't been through this but what exactly is the process of verifying a failure? Must that be done with a camera inspection?

Also, in order to inspect the output baffle and connections, they'd need to dig up the entire yard. We have no way of knowing where those parts are. Or can the camera do that?

TIA

there is no need to replace the tank unless/until there is a verified failure

A leaking tank is a verified failure.

don't do it just because someone "thinks" it might be leaking - make them prove it

LOL, Yes, I'm sure the OP's septic tank is the one exception to the conservation of mass.

Also, in order to inspect the output baffle and connections, they'd need to dig up the entire yard. We have no way of knowing where those parts are.

Output baffle is usually at the other and of the tank from the inlet. The baffle is to keep the scum floating on top from entering the drainfield.

excuse me piedmontnc but your derogatory tone is uncalled for as is your unfounded knee jerk advice.

by the OPs own account the 2nd chamber hasn't even been opened yet, and yet you claim the tank is proven to be faulty. you simply do not know that - just like I don't know for a fact that it doesn't leak. what I do know is that more investigation is needed before tank replacement can be justified.

OP - do as you wish. it is your house and your money. but I would seriously question any septic contractor who recommends a new tank without even opening the 2nd chamber and inspecting the output. that is a very basic step in system diagnostics. as is inspecting the first few drop boxes in the field. any competent contractor can locate them easily with an iron probe. they should also have a copy of your system drawing that is on file with the county health department. that will tell them where the boxes are, how many lines are in the field, how long they are, etc. this is easy basic stuff for anyone who knows what they're doing.

OP - one more thing - looking at the dates of your posts it seems you've only been monitoring the water level for a week, is that true? depending on water usage, it could take longer than that to fill the primary chamber. check it now - is it still at the same level as a week ago or is it rising?

the blockage in your pipe suggests a breach as others have said - this breach, when full of roots, could have diverted the inbound sewage out of the pipe and into the ground. a few gallons at a time. with intermittent use over the course of years and probable root intrusion sucking up water - no surprise the tank is low. but that by itself is not a big problem.

real question at this point - is the water level in the primary chamber rising with daily use, or is it staying low?

Lol, "unfounded".

Active system, flow in=flow out, simple physics really, sorry it's too complex for you.

right. and where have the flow volumes been established in this thread? since you're so smart tell me how much water has the OP dumped in the tank, and how much has leaked out? since you seem to have all the answer this should be an easy one for you...

btw I have an MSEE and design aircraft engines for a living. I know more about physics than you could possibly imagine. but you are a plumber so what do i know....

I haven't looked in this week but was thinking the same thing about water level and will do.

Not possible to access second chamber -- the tree is on it. Removing/processing that is the first level of h*ll.

Will get onto getting diagram from health dept. Had no idea but that is very helpful to know about as are talking points about what to check and how to diagnose.

I do feel this contractor knows what he's doing and has long experience. He's worked for me before -- no feeling at all that he is trying to upsell me or do anything unnecessary. He'll also stand behind any work he does. Will discuss all this with him.

sky-- in your situation did you replace a tank unnecessarily or was it just roots getting in?

It won't hurt to check the downstream components of the system ( so you know their location an dhow they're performing) but they have no effect on the water level below the outlet invert in the tank.

right. and where have the flow volumes been established in this thread? since you're so smart tell me how much water has the OP dumped in the tank, and how much has leaked out? since you seem to have all the answer this should be an easy one for you...

Doesn't matter, an active system with a properly functioning tank will have a water level just below the outlet invert. Anything below that indicates a leak.

btw I have an MSEE and design aircraft engines for a living. I know more about physics than you could possibly imagine. but you are a plumber so what do i know....

Well I do have a B.S. in mathematics and geology, am a registered environmental health specialist, a licensed subsurface wastewater operator, I also design, permit, monitor, and enforce septic systems, and have a masters in environmental engineering (which involves extensive hydrologic and hydraulic modeling) so...

no my tank definitely needed replacement. the output baffle was gone (corroded, dissolved). that could've been replaced with PVC, but the 2nd chamber manhole rim was also gone/corroded. so the lid fell in. at that point there was no effective way of keeping surface/rain water from flooding the tank and hence the field.

ironically, my county health department did not require me to replace it. they flushed a dye pack, ran 50 gallons of water, and when the dye didn't surface in the field they said it "performed satisfactorily". of course they weren't here whenever we had heavy rains and effluent surfacing in the back yard.

technically speaking, since my tank had no output baffle for (years maybe?) my field lines are probably clogged with debris to some extent. I'm keeping an eye on that. I have 9 lines each 100ft long. the first two drop boxes i opened and found what I can only describe as giant "sludged hair balls" clogging the lines - I could only clean out as far as I could reach (a very nasty job). the other 7 boxes were clean. with the new tank in place the last 5 lines stay completely dry all year whereas before they were all full of water all the time.

in your case I'd put a hose in the tank and fill it -- this may take all day. then see if the water level drops back down - and how quickly it drops. measure the levels with a long stick. this will give you a sense for how much water may be leaking. if its a slow leak and not a big breach of the tank they can actually repair it - although that may not be a good long term fix. but replacement is a big nasty job that will destroy your back yard -- just know what you're getting into before you do that.

Damn, that's a hell of a lot of surface water to flood out 900' of line, did roof runoff run over the tank?

I had a serious plumbing problem. I called a local company I'd used before. They have a good reputation, theyn get the job done right and quickly, usually. They recommended a dig job without using a camera. They wanted $9400.00. I got another company out, they used a camera to do a more accurate assessment of my problem, and they charged me $3200.00. Anything this big, you should get multiple estimates.

"I do feel this contractor knows what he's doing and has long experience. He's worked for me before -- no feeling at all that he is trying to upsell me or do anything unnecessary."

Last Friday I cancelled the job with the plumber. It wasn't sitting right with me. I wasn't getting answers and didn't feel all the issues were being addressed.

I am very grateful to all the posters here who pushed me to go further -- skyjumper and piedmontnc especially.

Called in our original contractor and his septic specialist who took one look at the pipe and said there was something wrong. He took a shovel and easily broke off the end coming into the tank. (Still no water in the tank though we could see the washing machine easily draining.)

Bottom line: he's coming tomorrow to do the initial excavation, remove the tree and check the entire septic line including the D box and the field. They think the field is ok but expect the D box needs replacement and that will improve distribution of the water evenly. sky's talking points just unrolled as we discussed it and our contractor made suggestions about how to get the machinery in etc.

They will dig up a portion of the patio to replace the pipe -- both need to be addressed -- and work from the tank back to the house to see what's what. The pipe in the basement looks ok -- that was checked too.

Once the tank is in and there's enough water to flow into the field, they can check that as well.

Starting tomorrow morning. This is a huge relief and, as was pointed out, the stakes are high. Plus, we are on wetlands. This certainly will be much more than the original estimate but there's more to do and it's being done correctly and well. The original mason can be brought in to put the patio back together.

For sure I will sleep more soundly tonight. Again, a million thanks.

Whatever else needs done in the long run, you may want to consider adding at-grade access risers over the inlet and outlet compartments to facilitate observation and maintenance, especially for cleaning the effluent filter if it has one. If it doesn't have a filter, it's a good time to retrofit one of those as well. If approved in your area, GAG/SIMTECH bottle brush filters usually fit easily into existing outlet tees; check with the county health dept.

piedmont -- Access risers have been discussed and agreed on. They are absolutely necessary -- digging to pump every two years is ridiculous. The gasket will be checked and he will check to see where/how the tank is leaking and if it can be repaired vs replaced.

Will ask about the filters, brushes and also consult on those. My thanks again.

Rain held us up a week. They excavated today and found a belly in the line to the tank. Opened the second hatch and the back of the tank looked ok. But to test, they filled the tank up and now are leaving it overnight to see if there's a leak or why water was only at 50% before it was filled. So far, textbook diagnostic as prescribed here. Very glad we didn't just go ahead and rip out the tank without also excavating the pipe.

Sounds like the sensible approach has finally been tried. Unless stump removal is necessary for tank area access or desired for esthetics, cutting the tree down should be sufficient for the tree removal. Stump grinding or digging is optional. Either of those techniques could damage the septic system.

Make sur eyou're not flushing any water down the drains during the test or you won't get any worthwhile information out of it.