How do I retrofit holding tanks to a "park" type travel trailer

I recently bought a 2006 unused Gulf Stream Cavalier travel trailer at auction.  It was a FEMA trailer (not the formaldehyde model) that has never been used.  The interior and all appliances are brand new and I think it will make a great starter camper for my family.
My question is:  with so many of these "park" type trailers that are not equiped with black or gray water tanks, is there a retrofit kit to add one or two holding tanks to it.  If not, where can I go to get step by step instructions for installing at least one large holding tank.  My alternative is to either only camp in locations that have sewer hookups, or use a large external portable tank.
Any advise is appreciated for this novice RV'er.

Tags: Cavalier, Gulf, Installing, Stream, holding, on, tanks, trailer

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Hi Steve!

I know a bit about these Cavaliers and what holding tanks they need. If yours is 32ft, like most or all of them are they would normally come stock from gulfstream with waste tank dimensions of 7.5"x30"x56".

To get something like that aftermarket you can get fairly close. This one from is fairly close, as is this one.
Thank you very much. I'll post on the progress of this project so that others in my condition will have something to refer to.
I have the 28 Ft version; all look the same from the web pictures. I'm new to RV trailers and also want to add a tank system. This may be a stupid question, but where do you place the tanks?
I know they should be near the axles if possible but do you remove/cut up the floor? The discussion thread talked about these trailers may have a predetermined location for the tanks, where?

Does anyone know the average size or recomended size for all three tanks, fresh water, grey & Black? I would like to balance the weight with the right size and not make the trailer too heavy.

Hey Jordan,

Im getting bombarded by my club director to get tanks on this camper. do i need 2 black/grey tanks? or can I go with one ? I know It's prob Imposable but do you have a diagram or pics i can take a quick look at ,I am up to Il ,code and even code but thig guy has a bug up his A#sSo instead of waiting till may i have a deadline of march 1st. unreal!!!!  camping is saposed to be relaxing 

2 36 gal tanks i went with a 32 gal fresh for weight in case i have to pull it.. filling it is nit that hard.
Hey Jordan, i recently purchased a Cavalier FEMA trailer also, with the waste tank, i need a fresh water and a gray water tank correct? Also will both of those be the same size or is the gray water a little bigger? Thanks for the help!  John

What would have come stock is 2 waste tanks, a black waste tank (toilet), a grey waste tank (sinks), and a fresh water tank. 


The 2 original waste tanks would have been the same size. This waste holding tank, or this waste holding tank should do the trick. I am not sure on the fresh water tank though. 

Hi, I also have purchased a 30ft Cavalier Camper and wish to install holding tanks...
looking for any direction... thanks
Hi Steve,I bought the same camper,and was looking for the same advice.I would be glad to share anything I find out.
I have actually found out that you can go a bit larger with the black and grey water tanks than what would come stock. You should be able to fit something as big as this one.
Does anyone have a list of parts needed for this install? I was just told today that the plumbing also has to be vented thru the top .. This is the first I've heard of that... anyone else heard this? I found some tanks on ebay for $50 plus $50 shipping..

not sure what else will be needed as in parts..
Installing the tank is done with either (or both) the use of a flange (around the tank) sliding into a bracket, and the use of straps going across the bottom of the tank to hold it up. It is recommended to secure the tank with both methods to ensure your tank is held in place.

The vent is fairly simple to figure out as long as you can figure out the space to have a pipe run up and out. You would need simple PVC fittings like these ones and pipe bought at a local hardware store. You would also need some sort of adhesive or plastic polymer to glue pieces together.

The vent is usuall just a 1" or so pipe running up and out to the roof where you should have some sort of vent cap.

Then a drain is also usually pretty easy to figure out provided you have the right end drain of tank and appropriate room to run the drain out. The drain is usually 3" cause if you go any smaller, you can run into clogging issues. It would run out to a valve.

Thats really the extent of it, but if you have any need of clarification, just ask :)




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