Main Sewer Drain Caps & Backwater Valve Install

[Mliu]

I finally completed the final install details for my Mainline Backwater Valve install. Overall pleased with everything, flows beautifully.

Looks good, and I don't see a problem with the offsets. But I don't see a cleanout. A cleanout should be installed just downstream of the backwater valve.

Did you remove the U-trap and those leaking PVC cap inserts in the cast iron fittings? Hopefully, you had all that cast iron replaced with PVC up to where the sewer exits the basement.

 

[Reach4]

Looks good, and I don't see a problem with the offsets. But I don't see a cleanout. A cleanout should be installed just downstream of the backwater valve.

I think that black cap is a cleanout.

http://backwatervalve.com/Upload/products/backwater-valves/diagram.jpg

I hope the cleanout shown in #1 is still there and the whole-house (U) trap is gone.

 

[Sponsor]

 

[Mliu]

I think that black cap is a cleanout.

That is a cleanout for the backwater valve. And I suppose it could be used to clean out the downstream sewer line. But considering the cost and fragility of those valves, there's no way I'd want a plumber driving a snake through there! I always see a dedicated cleanout port installed immediately after the backwater valve.

 

[Bert Lee]

Looks good, and I don't see a problem with the offsets. But I don't see a cleanout. A cleanout should be installed just downstream of the backwater valve.

Did you remove the U-trap and those leaking PVC cap inserts in the cast iron fittings? Hopefully, you had all that cast iron replaced with PVC up to where the sewer exits the basement.

The entire cast U-Trap unit is exactly as it was in the first pic, and about 15' downstream of the BW unit. Nothing done with that yet. I mulled that but since I doing the work it was simply too much right now to deal with the weight of the cast, find the correct donuts, etc so it stays. I do plan to make sure those caps are adhered in some sufficient manner though. I picked up a tube of Oatey/Hercules 25215 Plastic Seal that I am considering using to glue those cap assemblies in to add some security in keeping them from blowing out in the worst case back flow scenario. The caps would remain removable. If anyone has a better adhesive option I'd love to hear that.

The BW valve placement was based on the available space I had once the entire 'rig' was built and a section of existing pipe needed to be cut. It was bit short in the area directly adjacent to the Utrap, an just right a bit further up.

 

[Bert Lee]

That is a clean out for the backwater valve. And I suppose it could be used to clean out the downstream sewer line. But considering the cost and fragility of those valves, there's no way I'd want a plumber driving a snake through there! I always see a dedicated clean out port installed immediately after the backwater valve.

Good thought and I can always pretty easily add a clean out if need be at a later time. No need to rely on the black cap access point on the valve itself.

 

[Mliu]

Good thought and I can always pretty easily add a clean out if need be at a later time.

When you need it would not be the best time to add it.

 

[Bert Lee]

Maybe instead of those plastic cap things something like Fernco Qwik Cap does the same thing and brings a better peace of mind?

 

[Bert Lee]

When you need it would not be the best time to add it.

Worst case, couldn't it be snaked backwards from the current clean out in the short 10-15 feet to the BW valve? Anything from the Utrap out would be no problem from the trap as normal.

 

[Mliu]

The entire cast U-Trap unit is exactly as it was in the first pic, and about 15' downstream of the BW unit. Nothing done with that yet. I mulled that but since I doing the work it was simply too much right now to deal with the weight of the cast, find the correct donuts, etc so it stays.

Here's the problem. Now that you've added a backwater valve, there is nowhere for any backflow of sewage to exit and relieve pressure. Before, the flooded sewer relieved itself via your utility sink. Now it's trapped behind the backwater valve. So any pressure (head) in the fluid will be constrained by the piping between the street and your backwater valve.

I can see one of those PVC cap adapters popping out of the cast iron fittings because there's nothing restraining them other than a friction fit (which you already know is not very secure). Adding some sealant or adhesive will not help. What you currently have only works for a system that's not under pressure (like a normal gravity sewer drain line); it does not work when that piping becomes pressurized due to the backflow of floodwaters. This is why you need to remove those cast iron fittings from your home.

It sounds like you did the backwater installation yourself, so you already know how easy it is to work with PVC. I would remove all the cast iron up to the hub that's right at your basement wall (after the cleanout fitting). Then install a flexible PVC compression donut into the cast iron hub and insert your PVC pipe into the compression donut. Once your PVC piping is complete and secured, the pipe is physically constrained from being forced out of the compression donut (unlike the caps you currently have).

 

[Mliu]

Maybe instead of those plastic cap things something like Fernco Qwik Cap does the same thing and brings a better peace of mind?

I don't know of a Fernco cap that's designed to fit over the outside of a cast iron hub.

 

[Bert Lee]

Here's the problem. Now that you've added a backwater valve, there is nowhere for any backflow of sewage to exit and relieve pressure. Before, the flooded sewer relieved itself via your utility sink. Now it's trapped behind the backwater valve. So any pressure (head) in the fluid will be constrained by the piping between the street and your backwater valve.

I can see one of those PVC cap adapters popping out of the cast iron fittings because there's nothing restraining them other than a friction fit (which you already know is not very secure). Adding some sealant or adhesive will not help. What you currently have only works for a system that's not under pressure (like a normal gravity sewer drain line); it does not work when that piping becomes pressurized due to the backflow of floodwaters. This is why you need to remove those cast iron fittings from your home.

It sounds like you did the backwater installation yourself, so you already know how easy it is to work with PVC. I would remove all the cast iron up to the hub that's right at your basement wall (after the cleanout fitting). Then install a flexible PVC compression donut into the cast iron hub and insert your PVC pipe into the compression donut. Once your PVC piping is complete and secured, the pipe is physically constrained from being forced out of the compression donut (unlike the caps you currently have).

This is a good plan and I full agree with the popping cap potential. FWIW, it looks like they have been there a while and there was no utility sink before I installed one last summer so any previous sewer backups (which I am hearing are not all that uncommon) so they have been surviving the scenario you mentioned. My fear is how long... The utility sink was just the means to educate me that this problem exist. Those caps are the real weak link in my mind right now and if one fails I am in literal deep do-do. Right now I need short term peace of mind in securing those caps which has me thinking about some quick cap with a clamp option, IF there's enough space between the two "U" top sections.

 

[Mliu]

Worst case, couldn't it be snaked backwards from the current clean out in the short 10-15 feet to the BW valve? Anything from the Utrap out would be no problem from the trap as normal.

The existing cast iron cleanout is for snaking downstream. You're not going to get a snake through that U-trap. You may be able to snake from the upstream side of the U-trap, but it's a hard 90 degree bend from the U-trap into the upstream piping.

As I said earlier, just pull all that cast iron out and replace it with PVC. You don't need (or want) the U-trap and you will eliminate the possibility of one of those caps popping out during the next storm event. While you're at it, you can add the PVC cleanout. You only need one. I would put it immediately downstream of the backwater valve.

If you really don't want to replace that cast iron now, then I would strongly recommend physically strapping those caps onto the pipe so they can't be pushed out.

 

[Bert Lee]

The existing cast iron cleanout is for snaking downstream. You're not going to get a snake through that U-trap. You may be able to snake from the upstream side of the U-trap, but it's a hard 90 degree bend from the U-trap into the upstream piping.

As I said earlier, just pull all that cast iron out and replace it with PVC. You don't need (or want) the U-trap and you will eliminate the possibility of one of those caps popping out during the next storm event. While you're at it, you can add the PVC cleanout. You only need one. I would put it immediately downstream of the backwater valve.

If you really don't want to replace that cast iron now, then I would strongly recommend physically strapping those caps onto the pipe so they can't be pushed out.

Thank you. And you read my mind as I was just mulling an option for securing those caps in the short term across the top of all three with a 2x4 and small straps.

 

[Mliu]

Right now I need short term peace of mind in securing those caps which has me thinking about some quick cap with a clamp option, IF there's enough space between the two "U" top sections.

48 in. Natural Heavy Duty Cable Tie (15-Pack)

I would install them like this (with the zip ties going behind and completely around the pipe so it's held down evenly from both sides of the pipe):

 

[Bert Lee]

48 in. Natural Heavy Duty Cable Tie (15-Pack)

I would install them like this (with the zip ties going behind and completely around the pipe so it's held down evenly from both sides of the pipe):

View attachment 57671

Ahh yes, this is very good. I like it better than what I just did but for now I use what I have and it'll keep things safe until I can 'upgrade'. And, I know it's a half-ass*d plan all the way around but it'll buy me the time I need to properly address it. And, thank you, because our little conversation probably just saved me a huge problem. I went down to see is a 2x4 would work and while there gave a little twist to the plastic bits that hold the caps. Two are barely OK but the third one, closest to the wall, is so old and dried out that a light twist and pull had it removed and THAT is the worst case scenario. Holee Sh*t. What an awful setup.

Here's what I have in place at the moment

 

[Mliu]

Ahh yes, this is very good. I like it better than what I just did but for now I use what I have and it'll keep things safe until I can 'upgrade'. And, I know it's a half-ass*d plan all the way around but it'll buy me the time I need to properly address it. And, thank you, because our little conversation probably just saved me a huge problem. I went down to see is a 2x4 would work and while there gave a little twist to the plastic bits that hold the caps. Two are barely OK but the third one, closest to the wall, is so old and dried out that a light twist and pull had it removed and THAT is the worst case scenario. Holee Sh*t. What an awful setup.

Here's what I have in place at the moment
View attachment 57672

Looks like that will work as a temporary solution. Just realize that you'll probably still have some leakage of sewage since the existing compression donuts are in such poor shape.

 

[CG80SGAL]

And, while hard to see in the dark this was raging along my property line

Omg, and I thought my sump pump running 24/7/365 was a problem! You poor things!

 

[JerryDM]

That whole house trap is no longer recommended most places. If you do any changes in that area, such as adding a backwater valve, look to be rid of the whole-house trap.

The good backwater valves are "normally open". The ones with a hanging flapper almost invariably fail to close with time due to debris. I am not a plumber.

Hi reach4. I work for company that makes backwater valves, was curious about your comment on your area uses "normally open" bw valves. Why is that? We make Clean Check (traditionally NC for US market) and Check-Flo4" (NO for Canadian mkt). My plumbing colleagues mentioned NO was for Canada, and some parts of NY, but I never understood the reasoning. This is for my education only, not trying to sell you on our product line.

 

[Reach4]

A flapper hanging down over the opening, that opens during normal flow, will accumulate debris that keeps the flap from closing during a backup. It is intended to be normally closed until there is flow.

This illustrates normally open"

This is the plastic one common in Canada.

With no flow or normal flow, the gate lays down. If the water level rises because the sewer does not empty, the float raises the gate. One disadvantage of that is that you need a little extra drop between input and output. That is easier for new use, but for retrofit, you would need to dig up a longer area to flatten the slope before and after to let you have the little step down.

https://www.floodexperts.com/ is the company I was thinking of I think.

Their system with the pit in the yard will accumulate sewage from the house, and a float-controlled grinder pump will drive the sewage downstream of the valve. I was surprised that cities allowed that, but they do. They don't like basements flooding either. Overhead sewers are the best prevention of basement flooding, but this pit system retrofit costs maybe half the cost of overhead sewer retrofit.

NC is going to be more reliable with time I think.

 

[JerryDM]

A flapper hanging down over the opening, that opens during normal flow, will accumulate debris that keeps the flap from closing during a backup. It is intended to be normally closed until there is flow.

This illustrates normally open"

This is the plastic one common in Canada.

With no flow or normal flow, the gate lays down. If the water level rises because the sewer does not empty, the float raises the gate. One disadvantage of that is that you need a little extra drop between input and output. That is easier for new use, but for retrofit, you would need to dig up a longer area to flatten the slope before and after to let you have the little step down.

https://www.floodexperts.com/ is the company I was thinking of I think.

Their system with the pit in the yard will accumulate sewage from the house, and a float-controlled grinder pump will drive the sewage downstream of the valve. I was surprised that cities allowed that, but they do. They don't like basements flooding either. Overhead sewers are the best prevention of basement flooding, but this pit system retrofit costs maybe half the cost of overhead sewer retrofit.

NC is going to be more reliable with time I think.

Yeah, our biggest seller is NC (Clean Check). For my On Demand class on "Plumbing Mech Products", I simply tell them that while class goes into detail on our Clean Check, we also make a NO device called Check-Flo (per requirement for the Canadian market, and few areas in NY). Since I only "mentioned" Check-Flo and never knew more than the fact that it's NO, thought I'd research WHY they require NO BWV's.