# Why would you trap a 6" storm sewer



## plungerboy (Oct 17, 2013)

Today I jetted a 6" storm sewer and I learned it has a trap on/in it. I couldn't get past it with a 3/8 WH or my smallest head.

Why would you trap a storm sewer? 


what is the benefit of it being trapped ?


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## Unclog1776 (Feb 5, 2013)

What exactly was trapped?


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## tim666 (Mar 11, 2014)

Up here in the older part of the city it is a common sewer (sanitary and storm) requiring the storm drains to be trapped


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## Shoot'N'Plumber (Apr 27, 2013)

tim666 said:


> Up here in the older part of the city it is a common sewer (sanitary and storm) requiring the storm drains to be trapped


^^^Exactly! Same out here


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## plungerboy (Oct 17, 2013)

Unclog1776 said:


> What exactly was trapped?


Just past the test tee on a 6" storm drain. This is in a older neighborhood all the hour are from the 40's


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## plungerboy (Oct 17, 2013)

I understand why you might want to trap a San sewer but a storm I don't get. 

The only thing that I can come up with is that if it crossed over it could smell bad 

Any other ideas.


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## Unclog1776 (Feb 5, 2013)

If the main is a combo then that would make sense.


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## supakingDFW (Aug 19, 2014)

There's lots of older areas that run storm into the sanitary system...It's not common in the south though


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## Drain Pro (Nov 3, 2013)

It's done two ways up here in the city. Either every storm drain is trapped and then it goes to the main sanitary trap before leaving the house, or storm drains are not trapped until they reach a main storm trap generally located next to the sanitary house trap. Then both lines leave the building and generally tie into together within the first 10'. 
The county north of NYC generally does allow storm water to come back into the house. Area drains and roof leaders are either dry wells or they run a line to the curb. These are general scenarios, there's always exceptions to the rules.


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## Drain Pro (Nov 3, 2013)

A typo: the county north of NYC generally does not allow storm water back into the house.


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