Septic or sewer backup prevention questions & answers.

This article series explains how to avoid septic system backups when heavy use of the system is anticipated and for homes connected to a municipal sewer we discuss how to prevent sewer or storm drain backups into a building during rain or heavy flooding.

Q&A on Avoiding Septic Backups

These questions & answers on how to avoid a sewage or septic system backup were posted originally at BACKUP PREVENTION, SEPTIC - be sure to review that article.

On 2018-04-15 by (mod) - Would it be advisable to put a waste backwater valve on the line, just in case?

I don't know of any reason not to do so.

A backwater valve on a private septic system offers the same advantages as at a home connected to a private sewer - preventing sewage downstream from the valve from backing up into the building.

Keep in mind that if your septic system is in failure or is otherwise blocked outside of the home, the backwater valve will not and can not prevent sewage backups as toilets are flushed or other fixtures are run once the sewer line between home and tank is filled with back-up and thus the backwater valve is shut.

On 2018-04-15 by Marc

Building a new house with a septic system. Would it be advisable to put a waste backwater valve on the line, just in case?

Thank you.

On 2018-02-25 by (mod) - It is never "normal" nor acceptable for a building sewer line nor septic tank or drain system to fill with rainwater

It sounds to me as if the original design may have been inadequate.

Typical standards for good septic design would keep the bottom of the absorption field trenches 24" or more above the seasonal high water table.

That's separate from an issue of groundwater leaking into the septic tank itself. So some detective work is in order.

On 2018-02-25 by Michael

Thank you for that reaffirmation about whast I knew was the issue.. my wife, the plumbers that put the system in and everyone else just blamed it on the water table... even since it was brand new it's done this. I've never had an issue with plumbing like I have at this house. Thanks again

On 2018-02-25 by (mod) -

Michael

It is never "normal" nor acceptable for a building sewer line to fill with rainwater nor is it normal nor acceptable for rainwater, surface-runoff, or subsurface groundwater to flow into the septic tank.

Common causes of septic tank flooding include a failed drainfield, blocked drainfield piping, or surface runoff leaking right into the septic tank.

It's time to have a thorough inspection of the septic system to evaluate its condition, find the leaks, and to decide if (by luck) it's a matter of fixing leaks or (bad luck) the drainfield is saturated and in failure.

On 2018-02-25 by Michael

Will a drain all the way to the house (single story no basement.. just conventional septic system with a leech field) fill up with water from heavy rain? It lasted for 3 hours before the system was unusable because water had already filled up to the clean out. Is it normal for g eound water to impact a conventional system like this and this fast?

It's almost like run off water is just pouring into the tank. I've diverted water away from it best I can but it still persistently happens. The system did it before and was completely replaced 4 years ago, still doing it. (Drainage has been greatly improved as well as gutters installed to pull runoff away.)

On 2018-02-03 by (mod) - Toilet kept running while on vacation and over flowed septic tank.

Rick

You ask a perfectly fair question but I cannot give a reasonable answer - since the answer depends on many factors like drainfield design and type, soil properties such as percolation rate, drainfield size, other sources of soil water or groundwater, condition of the drainfield - and its otherwise functional state.

There could also be some subtle troubles like a septic tank with no outlet baffle whose flooding pushes solids into and clogs the drainfield, reducing its future life even if it appears to "work" after a while.

Start by having an onsite septic inspection that includes conditions in the tank and D-box.

On 2018-02-03 by Rick

Toilet kept running while on vacation and over flowed septic tank. How long till it drains back down to normal

On 2017-12-16 by (mod) - My septic tank keep backing up inside the house how do I fix it?

Clare

You need an onsite diagnosis from a plumber or septic expert to sort out what's happening.

There could be a blocked drain line that simply needs to be cleared, a damaged drain line that is collapsing and needs replacement, a septic tank that's lost its baffles, allowing sewage to back up into and clog the waste inlet piping, or a failed septic drainfield.

On 2017-12-16 by Clare

My septic tank keep backing up inside the house how do I fix it?

On 2017-12-08 by Carolyn

My septic tank has backed up twice and flooded our basement through the basement drain. What should I️ do why is this happening

On 2017-03-22 by (mod) - pop off valve to septic tank?

Sorry,David I don't know what you mean by pop-off valve.

If part of your drain system is clogging I'd probably first try a professional drain cleaning service with a rotary auger, then I'd have the line scoped to assure that it's not damaged and that it's properly sloped.

Watch out: If by "pop off valve" you are referring to a temperature or pressure relief valve on a heating boiler or water heater, and if that valve is leaking your equipment is unsafe and needs immediate repair.

But I don't know of a relationship between a TPR valve leak and a septic tank clogging problem.

On 2017-03-22 20:52:59.642418 by David

From the pop off valve to septic tank keeps clogging up

Question on basement sewer line backup:

I had a sewer backup into my home again yesterday at a basement toilet. Our main line has a sewer back-up flap [a wastewater check valve or backwater valve]. ...

Is there such a thing as a soft plastic or other material filled that would take the shape of the toilet and prevent water coming back up as overflow. Like I did with a ball of cloths, and a brick wrapped in plastic. It did the trick in an emergency, but it's not practical. - Anonymous by request.

Answer:

The advantage of installing a main sewer line backup prevention valve is that this device will avoid having to plug multiple drains in the home, and the valve, basically a big check valve, is always in place - you don't have to do a thing to get it to work.

If you are having drains backup, including at the toilet, then either your main sewer line check valve is not working, or your backup is occurring (as you suspect) because water or wastewater is draining into your in-house building drain/waste/vent system before or ahead of the main sewer drain check valve. While you could install another check valve at or near the basement toilet waste line, it makes more sense to install just one such valve to protect the entire building and to make sure that one is working properly.

Stuffing a rag or any other temporary "block" into a toilet or other drains is not the best approach to this problem. Not only can it be unsanitary and a health risk in some cases, but also, who is going to stuff drains when flood conditions occur and no one is at home?

Install a Main Sewer Line Check Valve or Make Sure Installed Valves are Working

First you may want to have your main waste line backup check valve inspected -if the sewer line is backing up from the street into your home, your main sewer sewer backup valve (waste backwater valve) or a flood guard valve is not working.

Here is a CHECK VALVE MAINTENANCE GUIDE [PDF] from the City of Ann Arbor, MI.

Don't Route Roof or Surface Drainage into the Sewer Piping System

Second, you should disconnect your roof drainage from the sewer piping system entirely, routing it to a nearby storm drain, or to the ground surface (at least 12 feet away from the building and to a location that drains away from the building to avoid basement flooding).

If connecting roof runoff drains to the sewer system is actually permitted in your neighborhood, try changing the drain connection to one that is downstream from your main sewer line trap and check valve.

By the way, in some communities it is illegal to rout roof runoff into the sewer piping. Doing so significantly increases the wastewater volume load on the municipal sewer treatment system so severely that during a storm the sewage treatment plant simply overflows, dumping raw sewage into nearby rivers or waterways.

Please see our full article on this topic, found

at SEWER BACKUP PREVENTION

Also see the special sewer line backup check valves discussed

at BACKUP PREVENTION, SEWER LINE. If your drains are already backing up, especially during a time of heavy use such as with guests in the home,

see SEPTIC BACKUP REPAIR.

If toilets are overflowing, see TOILET OVERFLOW EMERGENCY.

After the emergency, see CLOGGED DRAIN DIAGNOSIS & REPAIR.

For homes connected to municipal sewer,

see CLOGGED DRAIN DIAGNOSIS & REPAIR.

And for emergency toilets, see CAMPING & EMERGENCY TOILETS.

Comments:

(May 2, 2011) Anonymous said:
Thanks. This will prevent my toilets from backing up.

Question:

(July 26, 2011) Jim Mullen said:
During a recent very heavy storm and power outage, my septic tank backed up into my basement shower. It came out like a geyser. My system uses a lift station and with the pump out, the well filled up and gravity forced it back into the house. Should there be a check valve near the house? If there isn't one, any idea of the cost of installation?

Reply:

Jim the backup problem you cite is all too common, and I agree that a check valve at the drain line could probably have prevented this sewage backup. The cost to install is mostly in the labor to excavate, install, and cover up, not the part itself. In a straight-forward job in an unfinished basement where the drain line is accessible without breaking up a slab, I'd guesstimate $500. or less.

Question:

Sept 26, 2011) Faith said:
Hi I need help I dont know were my septic tanc in my house how can i find it?

Reply:

Faith, see

SEPTIC TANK, HOW TO FIND

Article link in the master index given above at More Reading

Question:

(Mar 12, 2012) Anonymous said:
will installing a check valve stop sewer gas from seeping back into the house when it rains?

Reply:

It may but it won't repair the failing drainfield that may be suggested by your complaint.

Question:

(Jan 29, 2013) fran said:
my grinder pump aotp switch keeps flipping off

Reply:

look for a failed check valve

Question:

(Mar 16, 2014) Anonymous said:
What do I do when my septic tank leaking from ground up

Reply:

Check for a blocked line out of the septic tank or for a failed drainfield.

Inspect the tank exterior and interior to diagnose the problem; if the tank is leaking to the surface because the outlet is blocked, causing the tank to overflow, the problem is in the outlet piping or drainfield.

If the tank is leaking out of its sides or piping near the tank because of cracks or damage the tank and piping are often repairable.

Question: basement flood after sump failure

(Apr 6, 2014) moe said:
we had a flood in our basement last week due to a sump pump failure, not a septic issue. now our septic system is over flowing outside, not into the house. could the two be related? our insurance is covering the flooding. could the septic issue also be from the flooding of the basement? The septic system was pumped out last summer, so should be working correctly. we have never had a septic issue before the flood in the basement.

Reply:

Moe,

I suspect that there is an important relationship between the basement flood following a sump pump failure and the septic system failure you are now seeing. I tend to mis-trust coincidences. But the situation may not be quite how it appears to you - or at least as I infer from your question below.

If the basement flood had as its root cause high roof spillage, surface water runoff or groundwater levels that put so much water around the foundation that the basement flooded - a condition previously avoided by the little Dutch Boy in the Dike basement Sump pump, then those very same conditions could well have flooded a failing or poorly-designed septic drainfield or soakbed.

In turn a flooded soakbed means that the effluent has trouble leaving the septic tank.
In turn all of that means you may see sewage effluent at the ground surface anywhere outside: at the septic tank, distribution box, or drainfield, or areas near the drainfield. Worse you might be at risk of a sewage backup into the building.

You want to take a look at the Septic Tank Pumping Fantasies we discuss at

inspectapedia.com/septic/Septic_Tank_Cleaning_Mistakes.php

There you'll see that contrary to your surmise, pumping the septic tank out last summer, while an important step in maximizing the life of the drainfield, is itself not a shred of basis for arguing that "the septic system should be working correctly".

Sorry.

Question:

(Apr 26, 2014) Anonymous said:
I have a problem with my septic plugging up at the baffle. There is only about six feet from the house to the tank. Dug up the line (most of it) to see if maybe roots were attacking the live but found no roots that deep. What is happening is the clog is cylindrical at the baffle and almost looks like the clog is happening in the pipe but is pushed out to the baffle. Use to happen every month or so not about every week.

Tank was pumped about 16 months ago so it should be good for another year or two. The floating scum layer is really think and hard. We use an additive for the tank so it should be in good condition. Is it possible that the scum layer is to thick already causing the intake to clog? Do you think I need to pump it again? I really do not want to spend thousands for some guy to come out and tell me the tank needs to be pumped again. I have a 2700 sq/ft house with only three people so I should last four or five years. Any help?

Thanks

Rob

Reply:

It's unusual for normal septic tank wastewater to clog the baffle unless there was an excess of toilet tissue or some object being flushed down the drain. More typically the waste falls into and onto the "pillow" of floating scum in the baffle area and pushes through it as needed.

But when the septic tank is pumped it's good practice to watch for that floating scum packet that's inside the baffle area to fall into and be removed from the septic tank. If it stuck and never was pumped out that could be a problem - typically solved by asking the pumper to be sure to remove it during tank pumpout.

Let me know what your septic pumping company says. In a properly sized tank it'd be a bit rapid to need to pump again after 16 months unless the building has very high occupancy

Question:

(May 16, 2015) Ryan Prough said:
We just moved into this home and it had a brand new septic system installed last year. Its been raining for a few days now and we have water seeping through the area around the septic line within our foundation.

I think the field is saturated but I have no idea what to do. Its not a lot of water by any means but it is supposed to rain for another day or so. Any advice would be greatly appreciated.

Reply:

Ryan

What you describe is a common problem: the trench carrying the sewer line acts as a natural catch point for surface and groundwater and worse, aims it right at the foundation wall where there was a hole punched to pass through the sewer pipe itself.

1. Be sure gutters and downspouts are unclogged and are directing water away from the foundation

2. same for site grading

3. Excavate outside the wall to clean and seal around the pipe penetration

4. If necessary install an intercept drain to slope properly to take water out of the sewer line trench, away from the foundation, and down-slope to daylight. If your site won't permit that you may need to install an outdoor sump - a more troublesome arrangement.

...

Continue reading  at BACKUP PREVENTION, SEPTIC - topic home, or select a topic from the closely-related articles below, or see the complete ARTICLE INDEX.

Or see these

Septic or Sewer Backup Articles

• ADDITIVES / TREATMENTS for SEPTIC SYSTEMS
• BACKUP, SEPTIC-SEWAGE WHAT TO DO
• BACKUP PREVENTION, SEPTIC
• BACKUP PREVENTION, SEWER LINE
• BLOCKED DRAIN REPAIR METHODS
• DRAINFIELD FAILURE DIAGNOSIS
• SEWAGE BACKUP TEST & CLEANUP
• SEWAGE BACKUP PREVENTION - home
• SEWAGE CLEANUP PROCEDURES & STANDARDS
• SEWAGE CONTAMINATION in BUILDINGS
• SEWAGE EJECTOR / GRINDER PUMPS

Suggested citation for this web page

BACKUP PREVENTION, SEPTIC FAQs at InspectApedia.com - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.

Or see this

INDEX to RELATED ARTICLES: ARTICLE INDEX to SEPTIC SYSTEMS

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