Learn About A Sewer Backflow Preventer: An Expert’s 9-Point Q&A Sewer Valve Guide

Sewer Service
October 19, 2021

by David Balkan

sewer valve installation

Installing any sewer backflow preventer valve is a big decision. It also has far-reaching ramifications, especially if you’ve experienced sewer flooding from a city sewer surcharge. Hopefully, the following video and Q&A points will help you figure out if a sewer valve is right for you. You may also learn which one may suit you the best.

Learn about the 2 typical types of sewer valves that are installed

Both of the sewer valve jobs explained below typically include a new main house trap and a new precast composite access pit with fitted covers. All Balkan work also includes finished cement work. In some cases where there are ceramic tiles or wooden floors, they would have to be considered and discussed in advance of the job.

If you’ve ever asked “How does a sewer backflow preventer work?”, get your answers with the 9-part Q&A guide that follows below.

    1. What’s the difference between a sewer check valve and a sewer flood gate valve?

    In our opinion, a sewer check valve is meant to prevent sewer backwater damage when the public sewer surcharges for just a few hours. One example would be during a heavy rainstorm. Whereas a knife-edged sewer flood gate valve holds back sewer backwater 100% for a prolonged period of time and acts as an ideal sewer backflow preventer.

    Therefore, the flood gate valve is designed for more severe weather or climate events. The other big difference is cost. A flood gate valve will cost roughly 250% more to install than a check valve.

    2. Do these sewer backwater preventer valves need to be cleaned, exercised, or checked in any way?

    About every three months the gate on a sewer flood valve needs to be raised and lowered. We supply the tool whenever we perform an installation. It takes less than a minute to do this. Sewer backwater check valves, which operate under a different principal, should be cleaned every year or so. The following video explains how to clean a sewer check valve, and also answers several questions.

    3. Is a sewer backwater preventer valve installed right behind my existing house trap?

    Absolutely not! It is vitally important that any sewer valve be installed before the house trap, and any other connection or drain outlet.  Installing a sewer backwater valve after a drain outlet or trap can lead to extreme sewer water damage. Furthermore, installing a sewer flood gate valve improperly will void the manufacturer’s warranty.

    To perform a proper installation (and required in almost all cases) your trap will be replaced and relocated, along with your fresh air inlet, and any drain connections in the work area. The sewer access pit will also have to be rebuilt.


    4. What is the time frame that my house will be without the use of the sewer?  I will need to let everyone in my house know.

    A typical sewer valve installed to prevent backflow installation would result in the loss of sewer service during a small portion of the 1st day, and most of the 2nd day. Usage will resume at the end of each work day.

    5. Does your crew send a camera up and down the drain line to inspect inside the house, and out to the street once it is open?  Do you check for pitch, sags, breaks, or obstructions?

    We can of course do a HD sewer camera inspection. It would be at an additional charge of  $250.00. This is often a good idea to see if there is any structural defect with the house sewer outside of the house. Interestingly, if your house sewer was able to handle the flow of a public sewer surcharge, chances are that it’s in proper working order.

    6. Your agreement states that “During times when the sewer valve closes water usage inside the building should be greatly limited or eliminated”. Is there any type of alarm or indication that the valve is closed?

    We do offer an alarm for the sewer flood gate valve. it is made by the same manufacturer as the valve itself. The cost of installation can vary depending on job site conditions, and the availability of an electrical outlet.

    sewer check valves
    Check valves greatly reduce backwater, but do not eliminate backwater

    7. Is there a minimal difference in drain elevations required to install a sewer flood gate valve? What if I have a floor drain or a shower in the basement?

    This is a vitally important point. For a 4” sewer flood gate valve there must be a minimal difference in elevation of 11” from the top of the drain pipe where the flood gate valve is installed and the lowest drain outlet in the basement.

    If there is not this minimal difference in elevation the flood gate valve will not close. This is due to a lack of the required air pressure building up in the air chamber. This is another reason why a sewer backflow preventer needs to be installed by an expert.

    8. Does the sewer backflow preventer installation cost vary depending on the type of device installed and job site conditions?

    Prices will vary by location or job site conditions. Of course, doing work in NYC (Balkan’s service area) is typically more expensive than in other areas of the country. Balkan does use a uniform pricing policy to ensure fair pricing, and almost all installations tend to be fairly uniform.  

    With that said, Balkan quotes are on-point and therefore firm. More importantly, we’ve spent a lot of time researching these valves and their proper installation. We’ve become experts at doing these installations.

    9. Will it affect my neighbors if I install a sewer valve to prevent backwater?

    For the vast majority of cases installing a sewer backflow valve should not affect your neighbors in any way. In some extreme cases, such as if your home is at the base of a hill, sewer backwater may seek the next lowest point to escape. In this particular case that might be the next lowest house up the hill or slope of the street.

    Closing points to consider about a sewer backflow preventer

    A knife-edged sewer flood gate valve:

    A sewer flood gate valve works automatically and stops sewer backwater 100% and for over a prolonged period of time. It requires the most skill to install, is the most costly, and is a sure cure to prevent future sewer floods from a public sewer inside your home. In almost all cases this installation costs over $9,500.00 for a full and proper installation, which also typically includes a new house trap and access pit.

    The installation requires repositioning many components of your drain system and has to meet the manufacturer’s standards.

    A sewer check valve to prevent backwater or sewer surcharges:

    A sewer check valve is a very simple and relatively inexpensive device. It is meant to hold back most backwater for a period of a few hours, it does not hold back 100% of stormwater. It is a much simpler installation, but must be done correctly and it usually requires repositioning your house trap and fresh air inlet. A typical sewer check valve installation will cost between $3,500.00 and $4,000.00, which typically also includes a new house trap and access pit.

    Expert Sewer Repair and Sewer Line Replacement

    The Balkan Team provides expert home sewer repair and sewer line replacement. We have expertise in all types of NYC underground plumbing. Balkan Sewer And Water Main Service was founded in 1952. Since its inception, the foundation of the company has been based upon integrity and honesty in all of our dealings. That solid foundation has enabled us to thrive in every economic climate. That is why guiding you through the decision of doing a sewer repair vs sewer replacement, particularly when tree roots in sewer lines are present, exemplifies our company culture of educating consumers. We feel the more you know, the better we’ll look.

    The year 2022 marked a milestone for Team Balkan

    The year 2022 actually marks our 70th consecutive year in business under the same family guidance. As we have grown, we have become increasingly dependent upon a “Team First” approach. What helps ensure a continuation of our high standards, overall integrity, and high company morale, is that same team approach.

    Complete client satisfaction has always been the number one goal at Balkan Sewer And Water Main. That is why we are NYC’s largest and most trusted sewer and water main service in New York City. Simply put, if it’s plumbing, and it’s underground, we do it. For over 70 years, and for over 90,000 New Yorkers to date, Balkan is “The Team You Trust”.

    post footer trucks on white

    Get A Free Quote
    David Balkan

    David Balkan is the CEO of Balkan Sewer And Water Main, the largest and most trusted service in New York City. David is extremely active in various NYC plumber organizations being the Chairman of the Subsurface Committee in the Master Plumbers Council, and Vice President of the Subsurface Plumbers Association. In addition David’s expertise is respected by officials of New York City agencies such as the NYC DEP, NYC DOB, and the NYC DOT. He frequently provides valuable input on a variety of industry related matters.

    Ready to Get Your Sewer or Water Main Issue Fixed?

    Get An Instant Quote
    • We manage every project from start to finish
    • We work quickly with instant quotes & rapid responses
    • We are licensed as a Master Plumber
    • Our GPS fleet ensures we are on time, every time
    • We are available 24/7 for emergencies
    • We back all replacements with a 10-year unconditional guarantee