Our Wet Bay in our 45LP Allegro Bus

Well, it is now time to talk about a dirty subject…Gray and Black Tanks! “Oh what joy!” Yea, I know! I am super excited about it also. (hummmm….)

Now many people asked about this and this usually means they are new to RVing and just do not really know. We have all been at that point of not knowing how this should be done and seeing we get asked at least three times a month, well, we are over due at making a post and a video that we can point people to. But this also gave me a great chance to put in a new sewer hose system that uses a totally different fitting that does not leak, with a MUCH more industrial hose that would take a lot to hurt it.

It’s called the Waste Master. Waste Master was designed and tested for years by Drain Master and then it was sold to LCI as they had a much larger distribution network. (Thus the like names) However the Drain Master company is still involved. (Ok, that was more than you needed to know, but thought I would mention it as you may find it on either site and the names are, well, the same but different.)

So, black and gray tanks. I will make this quick and easy as their really is not much to understanding the use of the tanks. (Ok, after writing the blog post it was not a quick post after all. Who knew their was so much to write on the topic?) Now I KNOW that people WILL HAVE AN OPINION on this. But this is how WE do it and the logic as to why we do it the way we do. And after all, we are the ones being asked. :) But of course, please feel free to comment and help others.

The “Black” tank is used to store your digestive waste. This comes from the thought that the waste is much darker in color. I guess it could have been called the “brown” tank seeing the “Gray” tank is used to store used water such as sinks and showers and as such the way it actually looks is gray when it comes out.  But oh well that is the way it is. (Guessing that maybe early on the tanks themselves were actually black and gray in color and so it stuck. Today they are usually the same color…black.)

RULE: Dump black tank first and then the gray tank right after it so it will flush out the tube. So what this also means is that if you are one to leave the gray tank open all the time…BE SURE to close the gray tank so you can build up liquid in it of at least 30% before you dump the black tank. You NEED to flush out the tube after you dump the black tank. So, when black gets to about 50%, close the gray tank and by the time you are needing to dump the black, you will have enough gray water for the tube flush out.

BLACK TANK – Leave this CLOSED all the time until it is time to empty it. “But Dave, I have full hookups and so I am connected to a sewer.” Well great! But leave it closed! “But why Dave?” Well, your “solid” waste has no way of being able to flow out of the tank without being pulled out by all the liquid waste and flush water that is allowed to build up when you have it closed. So if you leave the tank open, your solid waste would just go “Plunk” down into the tank and would just stay there while the flush water and “#1” would just run out. (That is until the outgoing opening gets plugged from to much solid build up then you are in for some bad times.) So leaving it closed allows for all the flush water and “#1” to build up and up and up. You dump the tank when it gets to be above 70% (Give or take.)  This way you would have built up enough liquids that when you open the tank it would create a “whoosh” and a suction effect that would then pull the solids out with it.

Then if your RV has a tank rinse, you turn that on when the meter gets down to about 20% left and let it run some. This will help to knock things down the walls and also help to push some of the solids towards the opening. After a few minutes I then close the black tank and let the rinse run some to put some liquid into the tank to start it off.  Again, I do not want solids to just go “plunk” into the tank and stick there. Having liquid already in the tank will help with it not sticking so it can be pulled out.

GRAY TANK – Ok, this is the touchy one. I think we can all agree that the black tank stays closed until needed to dump for the reason stated. But the Gray Tank can go either way…open or closed when hooked up to a sewer line. So what is one to do?  Well, like the black tank, the gray tank can also have solids in it from rinsing plates etc.  But what is worse, the grease or oils that can and do go down the drain no matter how you may try not to. They can and will build up on the side walls and even the bottom of the tank making a “mucky paste” of ick!

To prove this in the video you will see that I added a clear drain extension and left the gray tank OPEN for a month. You will see that over time an oil and grease sludge built up on the side of the clear tube that the gray tank was on. So what this means is if you leave the tank open all the time, you WILL get a build up in your tank as these will stick to the sides and grow in thickness. If however you leave it closed, then just like the black tank, you will then be able to have a lot of it pulled out when dumped at about 70% (give or take) as most will be floating on top of the water and thus be pulled out.

Icky muck build up from Gary Tank!

Now that is not to say that you can not leave the gray tank open, and a lot of people do. But that does mean you should be using something like Happy Campers Holding Tank Treatment to help treat the tank to dissolve it the best you can. We do this when we travel by having at least 50% in the gray tank and adding Happy Campers to it when we travel. As we drive it will slosh around and when we arrive, we will then dump the tank, thus clearing it out the best we can. We do try to wait at least 8 hours (say 4 hours of driving and then another 4 hours. Or better yet, letting it sit overnight after the drive and then dumping in the morning. (Gray tank only…If doing it on the black tank, dump right away as it will all be mixed up thus not having time to skink to the bottom.)

So…Do we leave ours open or closed? Well, that changes for us. If we know we will be doing laundry all day we will open the tank and thus we will not have a quick build up of gray water.  However, for the most part, we keep the gray closed and open as needed. Yes, of course you then tend to need to dump the tank more often then just when the black is full. This is one reason in the future I will be adding electronic dump valves so we can do it right from our bathroom. :)

“So Dave, why now make this post?”  That is because I just got a new hose system that needed to be installed and thought I would do it all at the same time.  Tank talk and tube talk.


You see, I have grown frustrated with the darn hoses because the one I used to use, the RhinoFlex by Camco, has gotten really bad in manufacturing IMHO. I went through two of them in three months because the hoses would split at the spine. In the past I had used them for years without issue. Then we bought the new coach and I wanted a nice new hose. Well it seems that they changed the plastic or something and I had two bad experiences due to cracks. So then I looked for another solution and I found the gray Viper hose by Valterra that was looking to be great! Well not so fast. While I like it a lot better than the RhinoFlex, I did end up getting a hole in it that I needed to seal with Emergency Tape and I did not like the fact it would not stay in place as the rubbery tube will not stay coiled when used. As such, even if you are 5 feet from the sewer, all of the 20 feet of hose will be out and uncoiled.

I then came across the Waste Master hose system. After being stung to many times, I was fearful of the price as I hated to spend more only to have more expensive issues. Also, it was different. And by that, I mean that it does not use the bayonet locks that are on almost all RV’s, it uses a CAM lock system. Unlike the bayonet locks that seem to be used ONLY in the RV industry for liquid. CAM locks are used across the world as a secure, leak free, easy to use hose linkage system. Ever see a fuel tanker


truck hooking up to unload fuel to a gas station tank? If so, you had seen CAM locks in use. They are used industry wide from fire trucks to tankers and even fueling jets. So why is it that the RV industry choose long ago to use a bayonet flitting vs a proven positive locking system for dumping waste? NO CLUE! I can only guess to make after market products that are only used for RV’s, thus being able to make more income.  HOWEVER, they still could have used a system that THE ENTIRE WORLD uses just as easy and still made their own hoses etc.

So…After researching and actually talking to the guy that came up with the CAM lock hose system for RV use, I was willing to modify our coach to use CAM locks and thus allowing me to use an industrial, patented, drainage hose!  (Do you know how hard it is to patent a hose? Lets just say it is as hard as one would think, a hose is a hose is a hose. Nope.)

Cutting off tab with hacksaw blade.

But when I say modify the coach it may sound worse than it is. It actually takes under 10 minutes to do and can be done by anyone. (Well, almost.  I asked Brenda to and she said no.) It just involved cutting off the four tabs that the bayonet uses on the bottom of the “Y” pipe and then glueing on the new CAM fitting to the end of the “Y” pipe.  POOF!  New industrial fitting that uses a hose that seems to really be something that would take a lot, and I mean A LOT, to hurt. Also when you have it in place where you want it…It says in place. It will not uncoil like the gray hose did.

I did mentioned the higher price of the system. However what I did not mention is I did spend more in three months on replacement hoses than the system costed me. So, in theory, this should be the last hose system I should ever have to buy.  Also, when we change coaches some day, I will simply buy a new “Y” pipe and replace the one I put the CAM fitting on thus allowing me to take my totally awesome new waste drainage system with me. (Well, as totally awesome as sewer waste goes.)

TIP: If you choose to also go with the Waste Master system, be sure to get the “Back to Bayonet Adaptor” also. Why? Say you are dry camping somewhere and they offer pump out service, then they will likely come with a bayonet fitting to attached to your RV. (Because that is what they would expect you would have of course.)  So you then can pop in the adaptor and have the correct fitting so you can then dump. You can also get a 20 foot extension hose for those times when you just can’t reach.

New CAM Lock Fitting Installed!!!

Attn RV Industry: Please be so kind to switch to a proven system that just works and does not leak. And by that I mean going to a CAM lock fitting that is simple to use, does not bind up, and does not leak.

After using this new system for a short time I will already go on record to say, I truly think that this is the best waste draining system hands down! From the correct type fitting, IMHO, to the totally great industrial hose, right on down to the “business” end having a shut off.

So I made a video.  (Of course) In the video I talk about the the tank usage, then go on to talk about hoses which gets me to the Waste Master, and then I do the install of the Waste Master and dump our tanks. Seeing the entire thing is 35 minutes long, in the beginning of the video I tell the starting time of each section. As such, you can jump to the part that interests you.  Enjoy our waste.