City Sewer Backup through Basement Drains

[Anonymous]

Recently, after a heavy rainfall, the city sewers backed up into my (and all my neighbors) basements through the drains in the floor. Is there any way to prevent this? I have heard about the installation of a backflow preventer, is this expensive? And is it placed outside the home on the main sewer line? Is there any other solutions?

[SylvanLMPParticipant]

Where floor drains or area drains are subjected to overflow as the result of backwater from the public sewer system, a backflow valve (check valve) should be installed at the buildings point of exit downstream of the building house trap.

Now you must remember as this device is preventing the city sewer water from entering your home it is also preventing your sewerage/drainage from getting discharged as the city pressure against the gate (flapper) inside this device will prevent it from opening.

So if you have any storm leaders or outside drains lines entering your internal drainage system your going to get flooded.

Before installing the backwater valves you had better check with local code as some codes do not allow their use.

[GuestParticipant]

code? is it ok in this day and age to have a combination sewer shallow enough to backfeed the taxpayers residence? put in a backflow preventer anyway

quote:

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Originally posted by SylvanLMP:
Where floor drains or area drains are subjected to overflow as the result of backwater from the public sewer system, a backflow valve (check valve) should be installed at the buildings point of exit downstream of the building house trap.

Now you must remember as this device is preventing the city sewer water from entering your home it is also preventing your sewerage/drainage from getting discharged as the city pressure against the gate (flapper) inside this device will prevent it from opening.

So if you have any storm leaders or outside drains lines entering your internal drainage system your going to get flooded.

Before installing the backwater valves you had better check with local code as some codes do not allow their use.

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[SylvanLMPParticipant]

quote:

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Originally posted by sewergod_27:
code? is it ok in this day and age to have a combination sewer shallow enough to backfeed the taxpayers residence? put in a backflow preventer anyway

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How about this hypothetical answer OK?

Lets suppose someone lived in a city like Boston Or, NY and these combination sewers are over 100 years old.

Lets also assume that since these sewers were originally installed a utility installed power lines and an under ground train system was also installed.

To make matters worse lets throw in a large water main say 48″ also installed above the existing sewer.

Now to make it more entertaining lets figure someone installed a sky scrapper above all this piping WHAT would you do to correct this condition of a century old system that was never designed to handle the fixture units connected?

Now how about the above advice you suggest about “put in a backflow preventer anyway”

Suppose the existing sewer pipe is cast Iron bell and spigot OLD and of questionable condition and now these folks listen to your sight unseen advice and the back pressure exceeds this cast Irons integrity are you willling to replace this piping for FREE?

Dont you think it would be wiser to VIDEO INSPECT this system to

1- make sure the existing lines are not back pitched

2- Make sure the existing sewer is not broken or defective in spots

3- That the spur connection above the city sewer is indeed above the crown weir of the sewer?

Back water valves are more or less a last RESORT

[Author]

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