Black Tank Flush Check Valve Leaking

[tazzman1961]

After using my black tank flush, I noticed water under my bathroom sink, which is where my flush line comes into RV. I noticed this black thing and I assume it's a check valve. There was water on/around it.
Anyway, it seems like it started leaking recently. Do they normally fail and start leaking. And to be honest, it may be my own fault. I have been closing my black tank drain while having water from the flush line coming it to tank to help move things around and then reopening the drain. I read that that is a no no and could cause problems. Could this have caused the valve to fail? I guess the simplest thing to do is to replace the check valve, but I wanted to give feedback if this is normal to fail, especially after what I did.
Thank you
Dean

[norty1]

While not recommended, that should not have anything to do with the check valve leaking.

More likely they are cheap plastic and a crimp is not as tight as it should be.

One of my past rigs, new, leaked the first time I used it. It was not crimped tightly. You will have to look and see which it is. Metal check valves are not expensive.

[Glamper64]

I would just change it out for a new one...mind you, you'll have to be a very flexible plumber, maybe remove the sink to make it easier. Sometimes they're installed backwards causing it to fail eventually...I don't think leaving the tank closed would cause the issue Imo. Good luck!

[tazzman1961]

I am hoping it's just the valve failed, and the crimps are good. Changing out the valve will be easy since it has threaded connectors on both ends. But I will have to connect water to the flush and see where it's coming from.
Thanks for suggestions

[norty1]

Look on Amazon: https://www.amazon.com/QWORK-Line-Ch...48&sr=8-6&th=1

They are reasonable and can be purchased with any thread configuration.

[tazzman1961]

Thanks for the link, but I don't see any configuration that has 90 deg and male threaded fitting on both ends. I just want to R&R, not add fitting or other wise.
Dean

[norty1]

https://www.amazon.com/Different-Spe...zcF9tdGY&psc=1

Here is another with male threads. If it has to be a 90, you can get these at most any hardware store with plumbing fittings.

[Glamper64]

I guess it's okay to replace the black thing with a brass check valve fitting? Will there be enough water pressure to work/open the brass valve? Pretty sure it will do the same job which is stop any gases or dirty water backing up into the main water supply. This is why you're supposed to leave black tank valve open when using the flush.

[TCNashville]

Eliminate the valve completely and install a city water inlet which already has a check valve in it. Now the check valve is on the side of your camper. Many on here have done this because no matter how many valves you install, they all leak eventually. Also, it is virtually impossible for the black tank flush line to contaminate the fresh water supply because it's a direct line from the wall to the tank but anything's possible.

[Arnold R]

Originally Posted by TCNashville

Eliminate the valve completely and install a city water inlet which already has a check valve in it. Now the check valve is on the side of your camper. Many on here have done this because no matter how many valves you install, they all leak eventually. Also, it is virtually impossible for the black tank flush line to contaminate the fresh water supply because it's a direct line from the wall to the tank but anything's possible.

That's what I was going to suggest. I just replaced the check valve yesterday - hint: first disconnect the valve from the inlet, then bend the line to the tank over to handle the other side. But those valves look pretty flimsy and should ideally be oriented with the top up. It makes much more sense to just take the valve out, connect the two lines with a double male connector, and screw a check valve onto the hose at the inlet.
Closing the black tank drain while the flush is running should not be a problem since I assume the tank must have a vent. I do it all the time: run the flush with the drain closed for 1-2 minutes a few times to get the tank really cleaned out.

[tazzman1961]

That is a good suggestion, and I may consider it to eliminate future issues with it.
I noticed on the replacement valves it says "this side up". The one that is installed on my RV that is sideways and somewhat down. Would this cause it to leak?
Thanks

[Arnold R]

I had been wondering about the original valve not being upright, too.
We will go camping next week, so I will see whether the new valve leaks. If it does, I will convert to the outside check valve.

Btw, one other thing to do is to make sure you have a pressure regulator in the line. I doubt the flimsy check valves will be able to handle the high water pressure at most campsites.

[tazzman1961]

Thanks Arnold. Funny, I was using a pressure regulator when I first started flushing and then decided to remove it. I am on a well and its good pressure, but I figured it would not be an issue. Now it's leaking, wonder it damaged it.
I am pretty sure that I will be removing check valve from inside RV and putting one on the flush hookup. I actually already have a inline check valve and going to get the 90deg pex fitting this week.

[tazzman1961]

I was planning to put the check valve and install a 90 deg pex fitting that is threaded on both ends so i can just put it in place without having to change the plumbing, but I am having a hard time finding one at any local stores. Online they want 14 to 17 dollars for one. BS, any suggestions on where to get one cheap?
Dean

[jbagnall]

Originally Posted by TCNashville

Eliminate the valve completely and install a city water inlet which already has a check valve in it. Now the check valve is on the side of your camper. Many on here have done this because no matter how many valves you install, they all leak eventually. Also, it is virtually impossible for the black tank flush line to contaminate the fresh water supply because it's a direct line from the wall to the tank but anything's possible.

If you go this route, do you also remove the check valve inside? Or just leave it alone?

Thanks!

[Okie Traveler]

I'm curious, is that a check valve or a vacuum breaker?

[SeanF]

Originally Posted by tazzman1961

After using my black tank flush, I noticed water under my bathroom sink, which is where my flush line comes into RV. I noticed this black thing and I assume it's a check valve. There was water on/around it.
Anyway, it seems like it started leaking recently. Do they normally fail and start leaking. And to be honest, it may be my own fault. I have been closing my black tank drain while having water from the flush line coming it to tank to help move things around and then reopening the drain. I read that that is a no no and could cause problems. Could this have caused the valve to fail? I guess the simplest thing to do is to replace the check valve, but I wanted to give feedback if this is normal to fail, especially after what I did.
Thank you
Dean

I had that exact problem. The device is called a vacuum breaker. First time I used it (on a brand new rig) it literally exploded and flooded the bathroom. Luckily my wife was on board when it happened else I wouldn't have known it was happening.

Anyway, I replaced it easily. Same thing happened on the second bathroom a couple months later! again I replaced it and it's working fine now.

Needless to say, I keep a spare on board now. And *oddly* enough, you can get them at practically any RV parts shop. Not that I believe in conspiracy theories or anything...just saying.

[PtL]

Originally Posted by tazzman1961

After using my black tank flush, I noticed water under my bathroom sink, which is where my flush line comes into RV. I noticed this black thing and I assume it's a check valve. There was water on/around it.
Anyway, it seems like it started leaking recently. Do they normally fail and start leaking. And to be honest, it may be my own fault. I have been closing my black tank drain while having water from the flush line coming it to tank to help move things around and then reopening the drain. I read that that is a no no and could cause problems. Could this have caused the valve to fail? I guess the simplest thing to do is to replace the check valve, but I wanted to give feedback if this is normal to fail, especially after what I did.
Thank you
Dean

Can either replace it or bypass all together. Black water tank needs to be open and empty when you flush.

[RoyB]

https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

This was the exact replacement for mine and it wasn't hard to replace.
There are many choices on Amazon.

[Okie Traveler]

The reason I asked if that is a Vacuum breaker, is because if it is laying on it's side like that it will leak. There is an air gap in it to prevent it from siphoning back into the supply hose.