• Welcome to the new and improved Building Code Forum. We appreciate you being here and hope that you are getting the information that you need concerning all codes of the building trades. This is a free forum to the public due to the generosity of the Sawhorses, Corporate Supporters and Supporters who have upgraded their accounts. If you would like to have improved access to the forum please upgrade to Sawhorse by first logging in then clicking here: Upgrades

Sewage Backflow

conarb

conarb

Registered User
Joined
Oct 22, 2009
Messages
3,505
Location
California East Bay Area
I have a case where the sanitary sewer backed up into a home causing damages, the sanitary district is denying liability claiming the home should have had a backflow prevention device installed. I've never heard of a backflow device on a sewer line other than a few I built with sewage pumps, it's apparent that the cause of the problem was improper maintenance of the sewer main by the sanitary district, has anyone ever heard of a code requirement for backflow prevention in a sewer lateral?
 
Thanks MLC, we are still on the UPC and I found it in §710.1 & 710.2, §710.3 goes into ejectors.

CPC said:
710.0 Drainage of Fixtures Located Below the Next Upstream Manhole or Below the Main Sewer Level.710.1 Where a fixture is installed on a floor level that is lower than the next upstream manhole cover of the public or private sewer, serving such drainage piping, shall be protected from backflow of sewage by installing an approved type of backwater valve. Fixtures on floor levels above such elevation shall not discharge through the backwater valve.

710.2 Drainage piping serving fixtures that are located below the crown level of the main sewer shall discharge into an approved watertight sump or receiving tank, so located as to receive the sewage or wastes by gravity. From such sump or receiving

tank, the sewage or other liquid wastes shall be lifted and discharged into the building drain or building sewer by approved ejectors, pumps, or other equally

efficient approved mechanical devices.
Click to expand...
710.3 (Goes into sewage ejectors)
 
This is a really easy one to miss as an inspector. Especially in hillside developments. Almost all basement fixtures will require a backwater valve. Make sure valve is located in easily accessible and easy to clean location as they foul often.
 
We check for them regularly after some kids tossed a bunch of junk in a sewer main, causing a massive backup in a subdivision. City took some lumps on that one for not requiringbackwater valves before. (Fortunately before my time.)
 
In our City it is required to have a loose fitting cap at the 2 way clean out at the the curb, and either a pop up or loose cap at the building to prevent back up, and damage in the home.
 
David said:
In our City it is required to have a loose fitting cap at the 2 way clean out at the the curb, and either a pop up or loose cap at the building to prevent back up, and damage in the home.
Click to expand...
Now that you mention it I remember those, we had an aluminum dome on the lateral just outside the building, but somehow I don't see them anymore. I bet it's a sanitary district requirement if not in the plumbing code. Anybody know what those things are called?
 
Here's the device , note that they say "If you don't have one, it is in your best interest to install this device now". They don't cite a mandatory regulation.

​
​


​
index.cfm
 
We had to install some in a few areas of town at the last city I worked for.

I know California has it's own version but here is what the 2009 IRC specifies.

SECTION P3008

BACKWATER VALVES

P3008.1 Sewage backflow. Where the flood level rims of

plumbing fixtures are belowthe elevation of the manhole cover

of the next upstream manhole in the public sewer, the fixtures

shall be protected by a backwater valve installed in the building

drain, branch of the building drain or horizontal branch serving

such fixtures. Plumbing fixtures having flood level rims

above the elevation of the manhole cover of the next upstream

manhole in the public sewer shall not discharge through a

backwater valve.
 
Mule:

While California has greatly increased and adopted the IRC it has deleted the entire plumbing section and deferred to the UPC based CPC, §710.1 of the CPC I quoted above is similar to the P3008 you just quoted.

I'm now of the opinion that if any plumbing fixtures are below the rim of the nearest manhole cover backwater devices are mandatory, if you are above they are voluntary but recommended.
 
& & & &

Conarb,

From Section R324.1.6, `06 IRC - Protection of water supply and sanitary

sewage systems.

"New and replacement water supply systems shall be designed to minimize or

eliminate infiltration of flood waters into the systems in accordance with the plumbing

provisions of this code. New and replacement sanitary sewage systems shall be

designed to minimize or eliminate infiltration of floodwaters into systems and discharges

from systems into floodwaters in accordance with the plumbing provisions of this code

and Chapter 3 of the International Private Sewage Disposal Code."

In some areas prone to flooding, the back water valves would be one proposed

method to address protection of the sanitary sewer systems.

& & & &
 
It is also important that the backwater valve serve ONLY the fixtures that are below the manhole. Fixtures above the manhole tie in to the sewer after the backwater valve. If there is a problem the basement is flooded with poo but the rest of the system still works.
 
the backwater valve protects the basement from municipal sewer line back-ups,

helps to keep those portions of the house system lower than the next "up-stream"

manhole from "filling with poo".

if you live in an older town with ageing muni. infrastructure backwater valves can be

a good investment regardless of manhole location.
 
Back water valves are good if you have any fixtures below the next up stream man hole however if your a plumber they are a nightmar if you have to clean the sewer line. I had to clean a sewer line with one, one time when I still worked on the outside and the cable go stuck in the flapper the access to it was around 8 foot in the ground out side so to get my cable out of the sewer I had to run both bathtubs in the basement and have the home owner flush the toilet. It was a long day that day.
 
You must log in or register to reply here.
Top