Frequently-asked questions about installing, diagnosing, or repairing septic tanks & drainfields.

These septic system articles explain how to buy, inspect, install, test, diagnose maintain and repair septic tanks, drainfields, and all other components of all types of septic systems. Page top: a peat mound septic system in Two Harbors, MN.

Septic System Buy, Install, Test, Repair FAQs

These questions & answers were posted originally at SEPTIC SYSTEM INSPECT DIAGNOSE REPAIR - the home page for an extensive library of onsite wastewater treatment and disposal systems.

On 2016-03-23 by (mod) - I know for sure I am replacing my drain field.

You're addressing the concerns that I'd worry about too, Joe. Your state may require a minimum distance, say 2 ft. between the bottom of the septic drainfield or trench and the seasonal high water table.

See what your health department wants and let me know. Do this before deciding how much fill to bring in to the site.

You will want to get ground water away from the septic tank and to keep surface runoff away from the fields regardless. It's easier to seal the pipe connections to the tank (against ground water) than the tank top.

But both are possible. Install septic tank top risers, sealed to the tank top. That may solve that problem.

On 2016-03-22 by Joe P

I know for sure I am replacing my drain field. The ground water that has saturated my drain field is from my pump tank. That what I meant by saying my drain field is saturated from ground water. I do have slope in my yard which lets rain water run off my field.

I got advice from a septic system owner/installer. He did say get fill dirt and raise my yard up even higher than it is now and then install the new drain field. I plan on doing about a 12" lift of fill and top soil so I can raise my field. That's just part of the problem.

I do know that my system pumps several times after real big rain storms. I'm hoping by digging around the outside of the tanks that I can find where surface water could be entering tanks. I'm guessing the gasket on the top lids are not sealed anymore.

Or worse, the walls are cracked. I'm trying not to have to replace several thousands of dollars worth of tanks, by repairing what I have. Like I said, they are only 20 years old, young for a concrete tank I would think.

I kind of just wanted some reassurance of how I plan on repairing the tanks was acceptable or just plain old crazy.
Side note: you would think that the seasonal water table was taken in account for when the system was originally installed. Just saying.

On 2016-03-22 by (mod) -

Joe

If the drainfield is saturated from groundwater you need to redirect the ground water; also seal leaks into the septic tanks and direct water away from the tanks.

If you can't get a couple of feet between drainfield trench bottom and top of the seasonal high water table your drainfield will not work. It won't treat the effluent that it discharges.

On 2016-03-22 01:57:47.803403 by Joe P

Ok, here we go, a problem that I have been diagnosing for,let's just say, a while. My septic system has 2 tanks, the second tank is a holding tank that gets pumped to the back yard drain field. I have water bubbling so I know my drain field is done and needs to be replaced. I also know it's only 20 years old. And more, I know that when it rains a lot, my tank pumps way more than we use water.

I do not have leaky toilets. I have done some repair to the inlet pipe from the house where ground water could have seeped through. I have re grouted with hydraulic cement around the neck of the view lid

. I still have excessive pumping after heavy rain. I do not want to replace drain field without repairing what I think is the heart of the problem. My drain field is saturated and stays saturated due to rain water seeping into my tank or tanks.

Has anyone ever had this problem. I am thinking about digging down beside both tanks, cleaning off the side walls, inspect for cracks or possible places it can leak from. Then install a cementisous product such as "thoroseal". Then roll with foundation sealer (tar).

Back fill and wait till the next big rain. Does this sound like a reasonable plan? I will do the work myself with some labor help. If I still have excessive pumping after rain storms, is it reasonable to say I need a new tank(s)

On 2016-03-21 by (mod) - Bump your wallet and brush the money

Bump your wallet and brush the money into someone else's pocket, maybe.

More seriously, NO drain line or septic drainfield system that simply removes roots from a pipe is going to give long-lasting repair: the roots grow back. Root poisoning contaminates the environment, does not offer a rapid repair, and may not be permitted in some jurisdictions.

Moving the drainfield is an option - costly. Would it be less costly to remove the offending trees and shrubs and most of their root systems?

On 2016-03-20 by Stephanie

Has anyone heard of the "bump and brush" method for clearing roots from LPP laterals? Method as it was explained to me involves taking a hammer to the end of the lateral and literally hammering it about 8" to move it to break up the small roots in the biomet, which are clogging the drain holes of the LPP laterals, and moving the pipes to a different area of the trench where there is minimal root growth to allow effluent to move through the lateral's small holes (5/32").

After the LPP is moved, a brush is then inserted in the line to brush debris, clearing the holes.

The entire line is then flushed. Copper sulfate is then flushed through the system after the procedure, then a month later, and then every 6 months. The 2 lbs. copper sulfate is mixed with water and introduced into the pump tank for dispersal through the system to deter further root growth. Thoughts, anyone?

On 2016-03-14 by ms.e.

we bought an older home and the seller told us they did not know where the septic tank was. after 2 years of living here we found it and found it to be a metal drum. can we sue the sellers to have them replace the tank with a new one?

On 2016-01-23 by (mod) -

Tom:

Typically you calculate the volume of rock needed, not the weight; That's the volume of the trench less the volume occupied by the pipe and by the fill-cover. When your septic contractor has recommended a specific rock size and type we might find estimates of the pounds per cubic foot if you still need weight.

On 2016-01-20 by Tom m.

can someone tell me the formula for calculating the number of tons of leach field rock needed for my leach field?

On 2015-12-10 by (mod) -

Let me know what you find and we'll take it from there

On 2015-12-10 by Ken B.

Thank you Dan. Not sure who manufactured the filter but I will check it next time I pull it which will be 12/1/15. I may have a clue as to where it was purchased so I will ask there as well. When I get the tank pumped it is unlikely they will measure scum and sludge or have the measuring stick ( it's a real mom and pop operation and the only game in town) to do so but will ask anyway.

If I was to follow te frequency per the table I would have real problems.

I did check original instructions from when the system was installed and I do see a note that says clean filter often from the installer. I did not realize often was to mean every month and when installed was difficult to get to, required digging. A few years ago I put in risers and covered w a fake rock so now easy access.

On 2015-12-09 0 by (mod) -

Bonnie,

Cleaning a septic tank will never fix in indoor sewage odor though it might give temporary relief if the problem was a blocked tank outlet or failed drainfield that in turn were causing slow drains or a sewage backup.

I'm unclear where rags were stuffed but that certainly sounds like an improper, possibly even dangerous, coverup of a problem.

Search InspectApedia.com for SEWER GAS ODORS to see a pair of articles that give more diagnostic details.

On 2015-12-09 by bonnie daniels

I have a septic tank and field with a 2.5 bath home built in 1995. Recently, we noticed a strong sewage smell in the master bath. We called to have the tank cleaned. They found the previous owners had stuffed rags in the system, since some blew out while they were cleaning.

The smell is still in the master bath! We have tried the vent; running water thru pipes to check for leaks, and various other things.

The smell seems to be coming out of the bathroom vent fan the strongest. The toilet has been checked and is okay. We are at a lose what is causing the sewage smell in the one bath. Any advice or suggestions?

90's

On 2015-12-03 by (mod) -

The filter is doing its job of protecting the drainfield; how quickly it clogs is also a feature of its physical size; have you checked with the filter company about typical service intervals?

About pumping frequency, go by the table we suggested, and the next time the tank is pumped, have the sludge and scum thickness actually measured; that'll give you objective data that will let you adjust from the general guidelines in the table.

On 2015-12-03 by Ken B.

Also wanted to mention it is unlikely I will go the route of measuring scum and sludge layers but thank you for that option.

Dan, thank you for your comments, very helpful. The diagram above does show colors properly, the only white area are the inlets and outlets. I did read your link on pumping schedule. As mentioned in the article my provider goes with the 'pump every two years approach'.

I'm pretty sure I have a 1500 gal tank size but will find out for sure.

Going by the chart I should be pumping a lot less so not sure why I'm having this clogged filter issue unless it is as you said regarding the 40% reduced settling time. My solution is really to pump it out. I should not risk an issue w the possibility 2+' snow on the ground and a back up on top of that.

As you said in the article, waste of money but wasting less money than the cost of a new drain field. Pumping now puts me in an 18 month cycle.

On 2015-12-02 by (mod) - Summarizing the point of "net free area" in the septic tank

Summarizing the point of "net free area" or liquid effluent area size in the septic tank is that if that area gets too small there is not enough effluent settling time in the tank. In turn that means floating solids are pushed out into the drain field or absorption bed, clogging it up and shortening the drainfield life. In turn that means expensive repairs.

By "septic pump" there are different topics:

1. pump out the septic tank - this has the object of removing scum, sludge and with it the current effluent (that liquid is needed for the pump to be able to remove the first two substances). This is done to protect the drainfield from clogging

2. SOME septic systems use effluent pumps or sewage grinder pumps - to move wastewater to a drainfield or to move waste itself to the septic tank.
SOME other septic systems (aerobics) use an aerator pump to increase the level of treatment of wastewater in the septic tank.

On 2015-12-02 44 by (mod) -

Ken

The net free area is pink in the page top sketch. It is labelled "liquid effluent"

Above the net free area you see floating scum and below it you see the settled sludge layer. (If it shows as white on your computer let me know a that's odd)

I appreciate the question and by no means do we expect everyone to know the lingo; our job is to translate this stuff into normal language and to make it clear.

At https://inspectapedia.com/septic/Septic_Tank_Pumping_Schedule.php we give a schedule for pumping septic tanks based on time, tank size, number of occupants or anticipated daily wastewater flow.

An objective measure of the actual conditions in the septic tank could be used instead of a generic time-schedule but most people are not able to safely open the tank nor measure the actual thickness of sludge and scum layers. That procedure is described at https://inspectapedia.com/septic/Septic_Tank_Level_Measurements.php

The USE of these measurements to determine when the tank really needs pumping is at PUMP AT WHAT SCUM SLUDGE THICKNESS - https://inspectapedia.com/septic/Septic_Tank_Level_Measurements.php#sludge1

There we note that

"Generally at a two year interval for septic tank pumping service the average septic tank in these size ranges will have a 400 mm scum layer with about a 200 mm sludge layer. With an average depth of 1600 mm, the solids content is about 600 mm thereby reducing the settling time by nearly 40%.

Therefore one may be right to suggest that the increase in total suspended solids exiting the tank will rise exponentially.

This may be a simplistic approach to calculating the frequencies between cleanings, however the evidence of it’s success is in the reductions of replacement leach fields."

On 2015-12-02 by Ken B.

After looking at your diagram at the top of the page I'm thinking the net free area is the white area, the inlet and outlet? So now the question is how often should a septic tank be pumped? Apologies for not understanding the lingo.

By pump do you mean an automatic submersible pump or pumping the entire tank? I thought you were referring to some sort of automatic submersible pump. I do pump the entire tank about every two years. Is that an appropriate schedule?

Tank was last pumped 6/3/14. Prior to that it was pumped 6/1/12. Is my filter telling me to pump the tank? And, what is the net free area? Maybe it's wise to pump anyway before winter, difficult to reach things once snow is in the picture and we get lots.

Thank you. Your response triggers these additional questions. What do you mean by the net free area? Is that the filter or the top water layer or something else? Also, I'm pretty sure I don't pump at all. I believe my tank has three chambers and they fill up into each subsequent chamber as waste water is fed into the system.

Eventually at the top last chamber is the outlet where the filter is stationed.

I think in theory anyway by the time things reach there most item should have settled into to bottom of the chambers by then. Do I need a pump in this system? I have been here for 9 years. This seems to be a recent problem but since I have identified this clog issue it has stopped the back up issue I was having every three months or so.

On 2015-12-01 by (mod) - if you are not pumping the septic tank often enough

Ken: just guessing but if you are not pumping the septic tank often enough the level of sludge and scum layer increase until eventually the net free area is too small;

in that case the wastewater in the tank remains agitated - too small a net free area means too little settling time. IN turn that means that the filter will clog faster.

On 2015-12-01 by Ken B.

The filter in my septic system needs cleaning every 30 days. I am in a large home however all kids have flown and it is just my spouse and I, so not heavy use. We have disposals but use very infrequently. I clean the filter every month and have easy and quick access via risers.

I have a yellow plastic filter with a maze of baffles which I can pull out of the tube in the tank and I make sure the filter when reinserted is inserted correctly into the tube with the outlet arrow on the filter facing the outlet of the tank.

How often should a filter need to be cleaned and what could be reasons why this filter clogs so quickly. The clog material could be described possibly as wet compost or a seedy material.

On 2015-08-16 by (mod) - gurgling drains suggest a clogged or partly clogged drain or a septic system that is in failure

The gurgling drains suggest a clogged or partly clogged drain or a septic system that is in failure, blocked, or backing up. That in turn can be the odor source;

On 2015-08-16 by Anonymous

I have a septic system. I have an odor coming rom the guest bathroom that smells like rotten eggs. Also when i take a shower in the master bath sometimes the toilet water starts gurgling. what can i do to get rid of this smell in my guest bathroom?

On 2015-06-12 by Anonymous

Anywhere close Morgantown I can buy calcium tablets for aerator system

On 2015-05-07 by (mod) -

Dorothy

Please see https://inspectapedia.com/septic/Home_Buyers_Septic_Guide.htm

where we give step by step advice for home buyers purchasing a property where a private septic system is installed.

On 2015-05-07 by Dorothy

The I'm buying has a septic system. I was made aware of this after I signed all the paperwork. Please what is my next step. I can be reach at 618_203_6296 or e-mail addressed childcare08@hotmail.com I would very much to know about septic tank.

On 2015-05-05 by (mod) -

Betty

The responsibilities of a home seller are defined in the contract of sale - something to review with care with your attorney.

However if a home does not have a working septic system that can certainly impede its sale to anyone, even if not prescribed by law, because most attorneys and real estate professionals know well that a home buyer won't be able to obtain financing if a home is not habitable.

(If you can't flush a toilet in most cases the home is considered not habitable). Even an all-cash buyer would be smart to follow the same criteria.

On 2015-05-05 by Betty

What are the legal responsibilities of a seller of a home which has a septic system? After testing the system, is the seller responsibility for adding a drainage field or building a whole new system?

Older Septic System Q&A

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Older Septic System Questions & Answers

On 2013-01-24 07:22:20.074461 by plumberrive

What is the best professional institute for plumbers, i want to start of my career as plumber!

On 2013-01-22 11:41:20.519650 by swtor/wik

Where to get training for becoming plumber, i have done my high school and now looking for some jobs, Is plumbing good, will be happy to have some good advice.

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On 2012-12-13 by looking for free links

You certainly have some agreeable opinions and views

Thanks for the guide

On 2012-04-03 by (mod) -

Carissa,

I'm sorry to say if your piping is root-invaded most likely it needs to be replaced. I've occasionally had a line routed out (call "Roto Rooter") but even when the line could be successfully cleaned, the trees or shrubs send roots back into that attractive nutrient source very quickly - surely you are not going to live with a rout-out every year.

Yes, you can wait until the next blockage but consider scheduling the job of finding out just what sections need replacement and having the work done when you don't have holiday guests or bitter freezing weather. It's more costly to have such work done as an emergency repair.

You might be lucky - the bad line section may be short and you might not need to replace the entire length - it depends on what materials were used and how much damage there is.

On 2012-04-02 by Carissa

I bought this house with septic tank system 1.5 years ago, and pumped the tank right after the house close. I don't have much info about the system, and recently it's blocked and we have a plumber came and temperately fixed the problem. So here is the problem and any recommendations will greatly appreciated.

I was told: the plumber can't really run his 'big machine' to clean out the blockage because the cleanout is only 2 inches, and he got a lot of roots out. He didn't have the camera with him, so he wasn't able to see what was main issue. The feedback from them is: pay them to run the camera line to see what happen; Or replace the 2 inches cleanout with a 4 inches one so they can run bigger machine to clean out the problem (very expensive).

And here is my question: if there is roots invasion problem, does replacing 4 inches cleanout and running bigger machine to clean help solve the problem?
What is the realistic solution? Should I wait until next blockage and fix problem then?
thanks

On 2012-03-06 by (mod) -

Zeke,
If you have not already done so,

- take a look into the pumping chamber when the pump cycles (watch out for falling in and fatal methane hazards, and don't work alone). The egg-shaped floating components you saw may indeed be the floating component of a float switch intended to turn the pump on and off.

In a dual pump backup system a second float is intended to turn on a second backup pump at a higher effluent level in the tank should the first pump fail. In other designs the pumps take turns running.

The fact that your sewage pump does not shut off points to a switch problem. Often the repair is to free a stuck float or to replace the switch component of the system.

The fact that you describe the switch cover open and muddy argues for a replacement of the entire switch control.

Watch out: turn off electrical power before touching electrical components - there is a fatal shock hazard.

Keep us posted - what you find will help other readers.

On 2012-02-06 by Anonymous

zeke said:

We have a 2 yr old leach field and a 2 yr old myers pump. The tank is from the previous system. Recently, the pump alarm began going off and holding the switch to hand pump would eliminate the high water light.

Basically, the auto feature was not working, so I thought it might be a float problem, so I looked inside the pump chamber. If it was the floats I was looking at, I saw 2 egg shaped plastic balls floating around on their side in the water.

Aren't those supposed to be attached to something? The pump still runs when turned on, but now the auto feature runs constantly and does not shut itself off. We have been turning it on/off by hand.

I am thinking that it may be an electrical problem also because the alarm only sounds when the breaker is flipped and the cover of the box on the pump chamber was broken and the wires and connections were full of mud. Any advice is greatly accepted and appreciated. Thanks zeke

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