Backflow Prevention

Users who are viewing this thread

jferello

Member
Messages
36
Reaction score
1
Points
8
Location
Doylestown, PA
Hey all,

What would be the best way to setup backflow prevention on this sewer line? I was not able to find any vertical backflow devices sold in the US, so I am thinking (2) horizontal ones?

Thanks,
Justin

File Feb 28, 11 26 47 AM.jpeg
 
Last edited by a moderator:

jferello

Member
Messages
36
Reaction score
1
Points
8
Location
Doylestown, PA
If the fixtures that these pipes serve are above grade then you do not need a backwater valve.
Bill,

The smaller pipe that goes off to the right is the drain for the washer, this is all in my basement. The larger pipe only gets fed from the first floor which is about 1-2' above grade.

Why does grade matter anyway, if it backs up, will it not rise up until it can come out?

Thanks,
Justin
 

hj

Master Plumber
Messages
33,600
Reaction score
1,037
Points
113
Location
Cave Creek, Arizona
Website
www.terrylove.com
That is a floor drain BWV, NOT for a main line. Until the water in the sewer gets higher than your floor, (and by then your house would be under water), it makes no difference HOW HIGH the water is in the sewer, your plumbing will still work. THat is the reason YOU HAVE an "overhead sewer" in the first place. You should have a BWV on the washer drain line if the standpipe is below the outside ground level.
 

jferello

Member
Messages
36
Reaction score
1
Points
8
Location
Doylestown, PA
That is a floor drain BWV, NOT for a main line. Until the water in the sewer gets higher than your floor, (and by then your house would be under water), it makes no difference HOW HIGH the water is in the sewer, your plumbing will still work. THat is the reason YOU HAVE an "overhead sewer" in the first place. You should have a BWV on the washer drain line if the standpipe is below the outside ground level.
hj,

Thank you for the information, so the 4" drain pipe is fine because the lowest point is the first floor which is about 1-2' above ground level. The washer drain line does not currently have a BWV valve, so I guess I should get one installed then.

So no matter what happens, the first floor toilet or sink will not spew sewage?

Thanks,
Justin
 

Reach4

Well-Known Member
Messages
38,796
Reaction score
4,413
Points
113
Location
IL
Thank you for the information, so the 4" drain pipe is fine because the lowest point is the first floor which is about 1-2' above ground level. The washer drain line does not currently have a BWV valve, so I guess I should get one installed then.
If the output of the standpipe was above ground level, you would not spew. Codes rules limit how high the standpipe for a washer should be. Just extending the standpipe to more than 42 inches above the trap weir could cause that trap to siphon. Some codes call for a maximum of 30 inches for that dimension.

If I raised my trap and standpipe high enough to get the top higher than the ground level, I would be in literal violation of codes, but my standpipe would not overflow. I am not a plumber, and I am not recommending that somebody else might want to override codes to prevent sewage backup without getting an exemption. I don't know how applying for an exemption would work.

Backup valves can leak. I do recommend having a plug, such as a test plug with a wing nut, that can block off the standpipe temporarily if needed. A valve could add backpressure to the fast flow of a washer.

A pump in a basin, that pumps the washer water up to where you drop it down into a sewer line is permitted usually. http://www.zoellerpumps.com/pt-la/product/62-drain-pump-series

So no matter what happens, the first floor toilet or sink will not spew sewage?
If the sewer got blocked, continuing to use your sink could cause your toilet to overflow if that is the lowest rim. If you have a shower or even a tub, the toilet is probably not the lowest first floor rim. But if it is just overloaded city sewers, then your sink use may push your water into the lowest neighboring basement that does not have overhead sewers or other effective protection.

Putting the washer and dryer on a different floor has some convenience advantages. Plus it lets you plug the basement standpipe.
 
Last edited:

jferello

Member
Messages
36
Reaction score
1
Points
8
Location
Doylestown, PA
Reach,

The toilet drain is the lowest thing on the first floor. There is no shower or tub on the first floor. The only other two drains are the kitchen sink drain or powder room drain.

All I want to do is make sure that if there is a large extended power outage, sewage will not back up into my house. I would not continue using my facilities if this starts to happen.

I am not sure I understand your test plug with a wing nut idea. The washer, water softener and iron filter all drain into that 2" pipe. The pipe is horizontal for about 10' then has a p-trap and rises about 2' and all the hoses just get jammed into the open top.

The open stand pipe is still about 1-2' below grade.

I guess if things start to backup, I could just start shoving towels into the drains?
 

Reach4

Well-Known Member
Messages
38,796
Reaction score
4,413
Points
113
Location
IL
I am not sure I understand your test plug with a wing nut idea. The washer, water softener and iron filter all drain into that 2" pipe. The pipe is horizontal for about 10' then has a p-trap and rises about 2' and all the hoses just get jammed into the open top.
http://www.oatey.com/products/mechanical-test-plugs is one collection, but there are other brands and other selections. Some are made to fit into the end of an open pipe, and others are made to fit into a differently-sized opening. I think the End of Pipe Gripper® Plugs http://www.oatey.com/products/mechanical-test-plugs/gripper-plugs/gripper-mechanical-plugs would fit, but your local plumbing store will have something.

Oatey Model # 33400 (1.5 inch) works, and is not in those pointed to in the above link.
038753334004.jpg

Typically you get the right size. Remove whatever is in the standpipe, insert like a cork. Then turn the wing nut CW.

You would unplug the softener and iron filter so that they don't regen. Alternatively, you could route them to a new higher standpipe or to the first floor.
 
Last edited:

hj

Master Plumber
Messages
33,600
Reaction score
1,037
Points
113
Location
Cave Creek, Arizona
Website
www.terrylove.com
Water has to obey the laws of physics so it CANNOT rise higher in the sewer pipe than the water in the "street", and until it DID get up to the level of the toilet, the toilet will flush PERFECTLY without overflowing. And, as I said previously, if it DOES get that high your house will be underwater and you would not be using the toilet anyway.
 
Top
Hey, wait a minute.

This is awkward, but...

It looks like you're using an ad blocker. We get it, but (1) terrylove.com can't live without ads, and (2) ad blockers can cause issues with videos and comments. If you'd like to support the site, please allow ads.

If any particular ad is your REASON for blocking ads, please let us know. We might be able to do something about it. Thanks.
I've Disabled AdBlock    No Thanks