Sewer line backup prevention Q&A.

This article series explains 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 including the installation and use of backflow preventers, backwater valves, check valves and toilet drain plugs.

FAQs on Backwater Check Valves to Prevent Septic or Sewer Backups

These questions & answers about backwater valves or check valves and other steps to protect a building against sewer line backups were posted originally at SEWER BACKUP PREVENTION - so please be sure to also review the advice given there.

On 2018-11-10 by (mod) - how to stop toilet paper from getting stuck in the check valve

If you're using I whole house sewer line full port check valve it's supposed to be self cleaning. It shouldn't be jamming with toilet paper. So perhaps we have the wrong valve installed or its installed in the wrong position.

I assume you're dreaming by gravity. If you have a check valve in a force main that's clogging then I suspect it's the wrong pump and a macerating sewage pump is needed.

On 2018-11-09 by LANA

Does anyone have any advice on how to stop toilet paper from getting stuck in the check valve and subsequently leaving the flap open and vulnerable to backwater flooding?is there anything I could do to get it unstuck from the toilet side without opening the valve itself?

On 2018-06-06 02:17:55.790378 by (mod) -

Nice going. I agree thst it's possible thst the snake penetrated but didn't clear the blockage.

What you reported will help others.

On 2018-06-06 02:01:48.374626 by Anonymous

Thank you again for the advice. Clog was in fact below the toilet, although not that far, so not sure why snake didn't reach it initially (maybe just didnt knock it through enough). Replaced with new ring and all is well in the world for now :-) Keeping same toilet, seems to have been mostly worry free for many years. Thanks again!!!!

On 2018-06-01 03:36:12.236405 by (mod) -

Thinking about this a little more, if there's a remote drain blockage that's pretty far out in the septic or sewer line then I would expect all of your dreams to be slow. It doesn't happen at a regular interval because if nothing has been drained for a while the line is sitting there just about empty and fills up with the first Wastewater that sent in.

On 2018-06-01 02:05:08.610395 by Anonymous

Okay, so maybe I rent a longer more powerful auger to go more distance? I appreciate the advice and reasoning.

On 2018-06-01 02:03:05.765225 by (mod) -

Usually what you describe is found to be a remote or more-distant blockage in the sewer line. Your auger or drain router may not have reached it.

On 2018-06-01 00:49:33.306538 by Steve Kaufer

Hello. I have a strange toilet issue that I can't seem to figure out. I have a 2-story home on a septic. All the drains and toilets in the house (with the exception of a small sink downstairs) are draining properly. The toilet I am having trouble with is on the second story (which is built over my garage).

My adult son reported a clogged toilet, and said when he tried to use the plunger, water suddenly came running out from under the base of the toilet. That water then leaked down in the ceiling of my garage, so I cut that piece of drywall out (directly below drain) to repair it.

I borrowed a 6' toilet auger from a friend and went to work. When I opened the lid to the toilet I noticed the water was mostly gone, with the exception of a very small normal amount in shallow bottom. I used the auger several times to full length, but met no resistance, and nothing was pulled back up. I flushed the toilet, and once again the bowl filled.

I tried using the plunger, but as my son had reported, some water began to seep from around the base of the toilet. I went down to my garage and was looking at the plumbing beneath toilet in the ceiling I had opened up. I saw some dripping coming through the cutout in the plywood subfloor where the drain pipe is at.

After about 4-5 minutes, I heard a whoosh of water as if the drain had cleared....

I went back upstairs, and sure enough the bowl is empty again....

I flushed it again, and this time it stayed full again.... Seems like water sits, and then after several minutes, it flushes through?

Not sure if this is maybe a plugged air vent or something for that bathroom? The two sinks in bathroom, and shower/tub are draining okay.

Any ideas? I'm dumbfounded at this point! Thank you again for all your assistance on this website!

Regards,
Steve

On 2018-02-18 by (mod) - Not all of these check valves can work vertically.

Mark

Not all of these check valves can work vertically. I speculate that's because it's a more costly as and challenging design.

On 2018-02-17 by Mark G

I've found very few vertical backwater (backflow prevention) valves, which seem like they'd be much cheaper to install in situations where the main pipe to the public sewer comes underground, then up vertically in the basement, since there would be no digging through cement.

Is there a reason not to use a vertical valve?

On 2018-01-05 by SteveP

We have a cottage in Maine in an area with minimal regs. We are on a modern septic system with plenty of capacity for the building size and use.

I am planning to add a shower in a downstairs bedroom. Although I can raise the shower pan somewhat (over a concrete slab) to provide drainage, the only workable way to join the main soil stack is directly below where an existing toilet wye/sweep drain enters.

While this is apparently allowed (all fixtures are vented as will be the shower) I am a bit concerned about the "surge" or slug of toilet waste passing so close to the shower drain entry. This will be a 2" wye, but the pipe run will still be below the 3" drain of the toilet above (the two pipes will run horizontally with slope to the soil stack - toilet above shower drain).

I am considering a check valve/backflow preventer in the 2" shower drain as the shower will also be the lowest point in the system so should a drainage problem ever occur (it is not unknown for lightly-used septic drains to freeze in the -20F winters, for example) any backup would appear first in the shower, which means it's out on the floor pretty quickly.

My only concern is that the check valve may impede normal shower drainage.

I suppose it will be critical to choose the correct item. I have seen transparent versions, which seems to be a good idea (I can design the connections so that - while hidden - they remain accessible) but I'm not sure they are rated for domestic drain use.

Does the use of a check valve seem reasonable in this situation? It would seem a location as close as possible to the main soil stack would be best.

On 2017-07-24 by (mod) - check valves that can be installed right at a floor drain

Mary,

There are check valves that can be installed right at a floor drain that may prevent sewage from backing up through the drain onto the floor. That device only prevents backups at the drain itself.

So if site elevations and sewer or septic piping were such that a sewage backup could move to a higher level you might find a sewage backup up into a basement washing machine or shower or sink even though the lower floor drain remained sealed.

A backwater valve such as the Canplas 223254WPK1 PVC Fullport Backwater Valve, 4-Inch unit is designed to be installed at the building sewer line at its point of exit from the structure. That valve will prevent sewage from entering the whole building's drain system from that point into the building, thus protecting higher fixtures or drains as I suggested above.

Of course the costs for the two parts are different. A main drain backwater valve may retail between $40. and $200. USD. before installation while a floor drain check valve might retail from $15. to $60. USD before the installation costs.

Installation cost for a backwater valve or for a floor drain check valve will vary widely for either valve depending on

- where you live and local plumbing rates

- the difficulty or ease of access to the installation location

- the necessity to cut out concrete to install the drain device

Figure $50-$250 for a floor drain valve installation, again depending on type of floor drain check valve device selected and the need to chop concrete

Figure a minimum of $150. and more-likely $250-$500. for a main sewer line backwater valve.
flag

On 2017-07-06 20:03:18.803834 by Mary

Please explain the difference between purchasing a $15 floor drain check or having a backwater value installed. Thanks.

On 2015-11-11 3 by EDD SALAZAR

I have a sewer underneat the house with 2 sumergiblebarnes pumps the 2 water back up valves installed 2 myears ago, but the inspector state are defective is possible that in 2 years go bad the others were wider and wptk well for 29 yeaesa this new ones why they are leaking back into the basin?

On 2015-07-18 by James

im installing a backflow valve on my sewer line but the sewer is 2' deep and the valve doesn't have a neck on it therefore the valve will be covered up when i fill in the hole, making it impossible to remove the cap when i wish to check out the valve. What can i do?

On 2015-06-25 by (mod) -

Karen we've moved your question and a detailed answer into the bottom of the article SEWER BACKUP PREVENTION .

On 2015-06-25 16:20:13.360870 by (mod) -

Re-posting
karen holmes said:
How much does it normally cost to put a check valve in..We had one backup of sewer and don't want another..

Question:

(Nov 2, 2012) m said:
i live in Brooklyn NY and have experienced a flood in the basement during both Irene and Sandy. This last time we had 5 feet of water that came up through the drain in the floor of the basement. Is there any product i can use that would prevent this?

(Mar 20, 2013) satex4@yahoo.com said:
One story house, no one at home, no water running, no rain for MONTHS but my sewer backed up and flooded half the house with raw sewage! How & why? Any ideas?

Reply:

Possibly, satex.

If the public sewer or even a private septic system is blocked and flooded with water or sewage from other site drainage or other sewer system users, the system can certainly back up into a home.

Question:

(June 2, 2015) anonymous said:
I have a Backflow Prevention (Check) Valve installed on my main drain line just outside my house. Can I install a second Backflow Check Valve just before the sidewalk as "double protection" (in case one fails)?

Reply:

Yes. In some situations and jurisdictions double backflow prevention check valves may even be required. Check with the manufacturer for the speciific product you intend to use.

...

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

Or see these

Septic or Sewer Backup Articles

• BACKUP, SEPTIC-SEWAGE WHAT TO DO
• BACKUP PREVENTION, SEPTIC
• BACKUP PREVENTION, SEWER LINE
• BLOCKED DRAIN REPAIR METHODS
• CAMERAS, SEWER / SEPTIC INSPECTION
• CLOGGED DRAIN DIAGNOSIS & REPAIR
• FLOODED SEPTIC SYSTEMS, REPAIR
• SEPTIC FAILURE SIGNS
• SEWAGE BACKUP, WHAT TO DO
• SEWAGE CONTAMINATION in BUILDINGS
• SEWER BACKUP PREVENTION
• SEWER BACKUP PREVENTION FAQs
• SEWER / SEPTIC PIPE CAMERAS
• SEWER LINE REPLACEMENT
• TOILETS, DON'T FLUSH LIST

Suggested citation for this web page

SEWER BACKUP PREVENTION 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 PLUMBING SYSTEMS

Or use the SEARCH BOX found below to Ask a Question or Search InspectApedia

Ask a Question or Search InspectApedia

Try the search box just below, or if you prefer, post a question or comment in the Comments box below and we will respond promptly.

Note: appearance of your Comment below may be delayed: if your comment contains an image, photograph, web link, or text that looks to the software as if it might be a web link, your posting will appear after it has been approved by a moderator. Apologies for the delay.

Only one image can be added per comment but you can post as many comments, and therefore images, as you like.
You will not receive a notification when a response to your question has been posted.
Please bookmark this page to make it easy for you to check back for our response.
Our Comment Box is provided by Countable Web Productions countable.ca

Citations & References

In addition to any citations in the article above, a full list is available on request.

---

ADVERTISEMENT

---