When do you need a sewer backwater valve?

[Rod N]

Hi Gents,

Installing a sewer backwater valve is all the rage here in the Greater Toronto Area as some older homes have been susceptible to sewers backing up in their homes.

When do you not need one?

I estimate our home drainage to be at least 8 ft higher than the city sewer. It looks like it would backup at the manholes on the street before it would back up into the house.

Your thoughts guys?

Thanks
Rod

 

[The Cobbler]

I guess it depends on how much flow into the sewers vs the flow out. suppose potentially the sewers could back up so much that the water under pressure would enter your house.
I have a similar situation, if i get a sewer back up from the sewer not being able to handle the flow, neighbors at lower elevations than me ( on the same line) would be swimming .

 

[The Cobbler]

backwater valves require maintenance every 6 months too, otherwise the likeliness of proper operation decreases

 

[rustyjames]

Happened at my Mother's house sewer backed up into the finished lower level, not a pretty thing to happen. Township paid for the cleanup and restoration but the experience really sucked. She has a backwater valve now.

 

[Rod N]

Our house does not have a basement and our bottom floor is easily 8 ft above grade to the street 80 ft away.

 

[pcmeiners]

Had one in a school building I managed, they do not always work.
You need good access to the gate, as I needed to clear it by hand a few times.

 

[Rod N]

Apparently they need to be cleaned/checked once a year, hence the access plate.

 

[ptgarcia]

Actual requirements vary from agency to agency, but my local water company (they control sewer, too) requires a backwater valve on any house if the finish floor elevation is less than 1 foot above the next upstream manhole on the mainline. That way if the main plugs up downstream of the house lateral sewage will escape out the manhole lid before entering the house. With some other agencies I've worked with that 1' higher requirement changes to higher by any amount. Also, if a 2-story house requires a backflow then that house requires a split sewer system (2nd story ties into house lateral downstream of backflow).

 

[wssix99]

I estimate our home drainage to be at least 8 ft higher than the city sewer. It looks like it would backup at the manholes on the street before it would back up into the house.

When it happens here, it's typically during a flood so bad that water is flowing like rivers in the streets (so the sewers are backing up through the manholes) and the folks who get hit have basements. (below street level)

If you don't have a basement and your lowest outlet is way above the street and you don't have a history of flooding, then it's probably safe to go without one.

Our house is in a low point in the neighborhood, but out lowest toilet is 4 feet above the street and we don't have a basement. We didn't get a preventer because we figured at the point our toilets had backflow; our cars would be flowing down the street on a river of sewage and we'd have far bigger problems.

 

[steveo1o9]

If you are that much higher then the main/manholes you should be fine. Like others have said a valve will require maintenance especially with solids in a sewer. Paper, "flushable" wipes, ect. will eventually clog the valve. So if its cheap insurance in your eyes be prepared to maintain it.

 

[Rod N]

That makes sense. On the other side of our street is the lake and is another 12 ft down. The backup has a place to go.

 

[larry4406]

The houses I build in Montgomery County MD require that all basement plumbing fixtures on a house connected to a public sewer be protected by a BWV. They don’t care if the basement slab is higher than the street or not.

So. YMMV.

Personally if your basement slab is higher than the street manholes I think your ok but then how much will the manhole cover relieve?

 

[peter2772000]

Having one will never ever cause a problem. 'Nuff said

 

[wssix99]

The houses I build in Montgomery County MD require that all basement plumbing fixtures on a house connected to a public sewer be protected by a BWV. They don’t care if the basement slab is higher than the street or not.

Maybe some plumbers provided that code language to the County for free?

Having one will never ever cause a problem.

I think I saw that saying in a book of Famous Last Words...

 

[Hilltopmasonry]

All the new homes in my area have an overhead sewer so that check valve is not required.

People install those when they have a gravity sewer which do backup sewage into basements occasionally

An overhead sewer discharges about halfway up on the basement wall so if you have a toilet or a shower in the basement it is actually lower than the sewage discharge port which then requires an ejector pit to pump it up to the sewer line. But since the overhead sewer line is much higher than the street sanitary sewer it doesn't overflow into your basement when the system gets overwhelmed due to rain water


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[BuschAndrew]

A sewer backup valve (waste backwater valve) can make the difference between having your basement flooded knee-deep with raw sewage and staying high and dry. They are an important part of any homeowner's plumbing system. They usually work using gravity, so, once installed, the device will work on its own to keep your home dry.
I got mine installed last year by the mainline backwater valve installation in Toronto. When I searched online for your query "when do you not need one?" I could find something which might be the possible answer. Here is what I found:
"Your home does not need a backwater valve if the water would drain from an upstream sanitary sewer manhole which must be lower than the inlet to the drain pipe in this home's basement."
You will find plenty of reasons why you need to get one installed for your home, especially if you are living in an area that experiences a lot of rain, or has occasional flash floods. While most cities prioritize their sewage and drainage systems, you cannot just rely on city works to keep your own home safe from unusually high rainfall. Instead, be proactive and install a backwater valve.
Backwater valves are becoming increasingly mandatory in homes, so check your local laws and see if you need one. In Toronto, there are some City rebates that you may qualify for. If you live in an older home before the law was introduced, you may have to install one to keep your house up to code. Like everything in your home, backwater valves need to be maintained, so be sure to clean and inspect yours every six months to keep it working.
You can read more about the functioning of a Backflow prevention device here http://www.brothersplumbing.ca/blog/backflow-prevention/backflow-prevention-devices-work/.

 

[Brian_WK]

As stated these are a maintenance item they need to be checked and/or replaced every year. The one person I know who has one, Basement below sewer level has 2 spare cartridges on hand and it is very accessible. He changes it every year in the winter right before spring thaw when the likeliness of flooding is high. The gasket seal on the flapper is always wrinkled and **** after a year and won't fully seal after that amount of time. He also has manual stoppers for all his basement floor drains, sinks and toilets. They get closed if there is prolonged flooding as relying on that flapper to keep back a wall of sewage is scarey.

Brian

 

[Rod N]

I talked to the township plumbing inspector to see what he thought and he backed up my theories and then some.

My house is so much higher than the street that the man hole covers would blow off before anything backed up into the house. At that point it would a disaster and we would have bigger problems than that.

As well we have a separate system for sewers and runoff, so it would not be sewage that would back up because of rain anyway.

Furthermore.

Someone mentioned it won't hurt to have one anyway. This contraption needs to be cleaned at least once every 6 months. If you don't you run the risk of your own sewage and water backing up into your house.

Although having this done in many cases can be warranted, I feel much of it is hype created by dishonest plumbing companies trying to make a quick buck. (who knew!) Materials should just be a few hundred dollars and opening the floor, installing the valve, and closing up the floor should not take more than a few days. Most of these guys want bank lone type of money to do it. My opinion.

 

[yeldogt]

What kind do they recommend today .... the flapper style can still leak.

 

[kbs2244]

"I talked to the township plumbing inspector to see what he thought and he backed up my theories and then some."

Advice from a local, respectable, expert is always preferable to keyboard opinions.

 

[peter2772000]

I talked to the township plumbing inspector to see what he thought and he backed up my theories and then some.

My house is so much higher than the street that the man hole covers would blow off before anything backed up into the house. At that point it would a disaster and we would have bigger problems than that.

As well we have a separate system for sewers and runoff, so it would not be sewage that would back up because of rain anyway.

Furthermore.

Someone mentioned it won't hurt to have one anyway. This contraption needs to be cleaned at least once every 6 months. If you don't you run the risk of your own sewage and water backing up into your house.

Although having this done in many cases can be warranted, I feel much of it is hype created by dishonest plumbing companies trying to make a quick buck. (who knew!) Materials should just be a few hundred dollars and opening the floor, installing the valve, and closing up the floor should not take more than a few days. Most of these guys want bank lone type of money to do it. My opinion.

I dunno what you guys have for SBV's, but there's nothing I could do to maintain mine even if I wanted to. Regardless, once a year I block my SBV and allow the sump to fill up in order to verify that the back-up sump pump kicks in, which it does. I have never, ever had to clean/maintain the SBV. I dunno what I could possibly clean anyways. The rubber seal is as flexible as when it was installed in my then-new build 15 yrs ago.

Again, at least as far as my particular type of SBV is concerned, I can find no reason not to have one and a few to have one

 

[pcmeiners]

"Apparently they need to be cleaned/checked once a year, hence the access plate."

Agree with Peter sounds like a scam a plumber made up for an easier $400......
Wow I never knew there was a schedule for blockage with certain SBVs, my school's gate would randomly block with solid when the sewers could not handle the flow with something jamming the gate. Never realized there were special SBVs which attract solids at the gate mechanism. I learn something new every day

"I dunno what you guys have for SBV's, but there's nothing I could do to maintain mine even if I wanted "
Not true, you could take the gate apart, polish the metal seal area with 500 grit. Any neoprene could be cleaned up and a bit of Armourall , re apply black paint to the valve body, all depends how much you into SBVs

 

[peter2772000]

[/QUOTE]

"I dunno what you guys have for SBV's, but there's nothing I could do to maintain mine even if I wanted "
Not true, you could take the gate apart, polish the metal seal area with 500 grit. Any neoprene could be cleaned up and a bit of Armourall , re apply black paint to the valve body, all depends how much you into SBVs [/QUOTE]



Cute LOL

 

[P Dubya]

Maintenance... Not everybody will always get that done. I have seen quite a few times when some small bit of solids will be stuck in the one way valve holding it open ever so slightly. You still feel like your protected but the sewage can still back up from the downstream side of the valve. For total and absolute protection I have installed full size/full flow ball valves with above ground access risers on sewer lateral on several houses.... Big storm and inundated sewers? Shut the valve. Nothing is coming in the house.