Septic Tank Leak

By seam do you mean a split tank with a bottom and top half, and possibly stacked splice sections to increase the volume?

If so, you use a rubberized caulk that comes in a roll, and is placed in the seam. The weight of the upper concrete sections squeeze this caulk into the seam.

At least that is what was used on my now 30 year old septic tank. And the septic tank company provided this as part of the tank cost. I also used this to seal the 4" PVC pipe on the inlet and outlet. And in the hoist fixture holes used to lower the tank into the ground.

Material of construction?

Accessibility to leak?

Is leak above or below normal fluid level?

The tank has an upper and lower section.The leaking seam is about 36 inches down.It probably had the rubber seal between the sections when it was installed about 25 years ago.It is now leaking from the inside out.I have dug down to the seam and found a whole at the seam.I don't know how far around the tank it goes.The tank has very poor access as tank was installed then house was built in front of it.On the other side is a steep gradeThe liquid level in the tank is at the same level as the whole and it is wet below the tank.It in not wet at the hole I have uncovered which tells me it is leaking at another point.HELP!!!!!!!!The tank is cement.

I don't envy you. You'll need to flush the area of the leak and when it's dry use a caulking gun and some sealer. The type of sealer is up to you, but I'd get a good one.

How to Use Exterior Caulks & Sealants for buildings

Table 1-13 lists properties of many different types, but If you have an old fashioned hardware or plumbing supply, I'd go ask them to sell you their best goop, and a caulking gun.

Left to chance, I'd probably go with a good Butyl caulk.

I don't know if they offer foams that expand when applied, but a good plumber or hardware guy would.

Good luck.

How do you know it's leaking at the seam? The seam is several feet down.

The old way with traction engines was to put oats, straw and pig-droppings into the boiler, and steam it. It sounds like you are a third of the way there.

I thought a septic tank was supposed to leak into the surrounding soil. Where do you think all of that liquid goes? Now a collapsed septic tank is a completely different problem.

The tank is not supposed to leak. That function is for the drain/leech field.

Is this a recently installed tank? If so, a phone call to the contractor is due.

How big is the leak? If it's only leaking liquid, then that's a different problem. With the dry weather, enough solids will get caught in the seam and seal it. If it's a large gap at the seam, you'll probably want to seal it with caulk.

If it's older it's probably going to be hard to get anything to stick in place, the goo that's leaking out will probably not make it easy for caulk to stick.

Call a Honey Dipper and ask them. They are confronted with the same problem more often than you or the CR4 forum.

I'm honest. It has been a long time since I didn't have sewers. Where I lived with a septic tank they always dug and installed another one and didn't mess around with fixing them.

Good Luck, Old Salt

I symphatize with your case although I'm not familiar with the type of tank you have. Sounds like there is more than one leaky spot, which is not unusual for an old septic system. How often do you empty the tank and how long has it been since the last cleaning?

Because the access for purpose of inspection from outside is limited, you would need to empty the tank completely and inspect it from inside. That will enable you or a professional to find and fix all cracks at once. Abrade the area along the cracks before applying cement or high-strength sealer to ensure a good bond. In any case, get a second opinion from several professional contractors in your area.

Fixing this problem involves some advance planning as the empty tank has to be kept dry during the repair and you may have to use your neighbors' facilities or move out for a few days. Wish you best of luck, feel free to report back on the outcome and lessons learned!

The water activated resins work wonders and are permanent from my experience also using an activator can speed up the activation of the resin. I used this system on the cracks that developed on my underground house and never saw a drop of water again. I suggest you pump the tank at least below the seam or crack. Normal procedure is to drill in about 2 inches and install the port which has a grease zerk installed then you can pump the resin and activator with a hand held grease gun. There should be lots of crack repair firms in the area as the equipment is not expensive. Just google crack and water sealing. I have an associate retired now that took care of massive water leaks in mines and excavations with a similar process.

There's a few ways you can repair a leaking septic tank joint.

1. Obtain a backhoe to remove the soil atop and around the tank. Thoroughly hose off the tank exterior, especially at the horizontal seam. With the backhoe, lift the top half of the tank. You'll need heavy duty chains to do this. Hopefully the old lifting lugs or rebar hoops are still intact, otherwise you're out of luck, unless you install new expansion anchors to aid in lifting the top. Clean both top and bottom portions of the tank seam. Install Butyl rope asphalt-based primer to the seam surfaces, Install the Butyl rope along bottom horizontal ledge portion of the seam, making sure you adequately lap the ends of the rope. Reinstall the top section of the tank. The weight of the upper tank section and the backfilled soil will compress the Butyl rope, thus sealing the seam.

2. Expose the entire exterior surface of the horizontal tank seam. Have the tank pumped out first. Thoroughly clean it with a power washer. Let it dry. Rout out the entire seam, all around. Apply a low slump hydraulic cement having a short set time and high tensile strength.

3. If you have observed exposed welded wire mesh and/or rebar, then the concrete tank strength may have been compromised. With a mirror and flashlight you must inspect the tank interior, especially the underside of the tank lid, for excessive concrete deterioration and exposed steel reinforcement. Sewage produces hydrogen Sulfide gas that is very capable of eating away concrete and steel reinforcements. If there is a goodly amount of deterioration, then I suggest that you have the tank replaced. Make sure any new tank has Asphalt (Bitmastic, epoxy based) paint applied to the entire interior and exterior surfaces of the new tank, applied in no less than two separate coatings (minimum 12 mils DFT). The paint will prolong the life of the tank and costs very little....call it a cheap insurance policy against long-term failure.

At least in the USA-----Since this is being done in a potentially poisonous vapor space, hazardous chemicals present, not meant for human habitation, restricted entrance and exit and a few other things, compliance with the full OSHA standard for Permit Required Confined Space work, 29CFR1910.146,

https://www.osha.gov/pls/oshaweb/owadisp.show_document?p_id=9797&p_table=STANDARDS

must be complied with before doing any work under the conditions described in the standard. Everything must be complied with. It may seem a pain in the as$ doing all this but a homeowner (hobbyist) or other not fully trained person is at a much higher risk than someone with the training concerning confined space entry.

At a minimum this requires 3 people: the entrant; the attendant; and the rescuer. If the attendant is not qualified as a rescue entrant they can not participate internally with the rescue. Another rescuer must be present before the original rescuer can enter. In short, for every one in the confined space there must be a rescuer outside ready to enter. Also rigging must be provided for fast retrieval of any entrant/rescuer.

There have many documented deaths of personnel: residential; municipal; utilities; industrial and so forth. Most often the "immediate rescuer" who went in with no protection is the victim. Statistically, for every five confined space deaths three are rescuers. Most of these are "impulse" rescuers. In civilian life, most of the deaths are from cesspools!

Good Luck, Old Salt

You know how much I respect your civil engineering knowledge, but first do all the excavation work to lift the top half of a septic system, lift the top half, replace with a sound repair and then in step two pump the septic system dry? I'm not sure if you desire a memorable but safe failure, accidentally got the sequence wrong replying to a blog or my imagination is just running wild in this scenario.

Fred, I got my sequence reversed. By all means safety first. Pump the tank dry and let it air out for a few hours (or force air the darn thing with a blower), then remove the top section to necessitate the repairs.

Sorry, I didn't mean to confuse peeps.