Running Dual Black Tanks.....

[Colonel_Monk]

Howdy

I'm designing a compact travel trailer which is focused on extended dry camping and crossing the USA.

I'm liking the layout that I have but due to small size I've got the combo shower/toilet in the front of the trailer. This is fine except for I don't want the 42 gallon black tank in the front of the trailer. For weight balance I need to move it aft.

Though I have been thinking about a composting toilet, sounds to me like they can be a real hassle, especially if west of the rockies.

So I'm coming up with a plan to make this work, bear with me....

I'm thinking of placing a small black tank directly under the RV toilet. Probably something in the "several gallons" range. (they do exist)

Plumb that black tank to a permanent marine-style macerator pump.

Plumb the output of the macerator pump to my main black tank located near the axles.

When small tank is full, flip the macerator switch and pump it out into the main black tank.

Main black tank will drain just as all normal black tanks do.

I'd probably also put a 3" drain drop on the mini tank just in case there are problems it can still be emptied and flushed for "service".

Anybody done something like this? Comments?

Thanks

CM

[Fulltimer50]

Most have a problem of the gray water tank filling when dry camping.

[Colonel_Monk]

HadEnough wrote:
Comment is that gravity is your friend. Macerator pump is a complexity that solves a problem but that will break eventually.

Get different shapes for the tanks and put all freshwater and black water by the axles.

I'm picturing longer, flatter tanks situated so the longest stretch of the tanks are situated fore and aft.

This configuration balances all water over the axles, changes the location of the head to over the axle as well (move closet up front), eliminates macerator and is self baffling as they are long, skinny tanks situated "fore and aft" in orientation.

Thanks. I can appreciate this since I've had a flojet external macerator for a long time. They do wear eventually.... When working though they do work pretty well.

The tanks I have selected are 54" x 27" x 9" at deepest. Do you mean even longer and skinnier than that?

Maybe I need to try a 4th version of my layout again and try to massage it into submission. Being DIY, I won't be using some of the clever space saving stuff of a typical small RV. Bad back means I need a real bed. Right now I'm planning a murphy bed but it doesn't help with creating space for the bathroom "amidships".

thanks for comments.

[Colonel_Monk]

Rvpapa wrote:
Make real sure there is enough space in the second tank before you use the macerator. Might get real exciting and make a good U tube vid.
Art.

No doubt! I have been looking at the "reliable" sort of gauge, the kind that reads without having things in the tank to get mucked up. Since I wouldn't have a toilet to look thru as a sanity check I suppose a "log" (no pun intended) of how many transfers have been made would be in order.

[Colonel_Monk]

mat60 wrote:
Will this build also cost you more than just buying a RV? I thought about a build a long time ago with a 8x14 carog trailer.

Couple things... I design equipment trailers for a living. We have a shop with all the tools and a fair amount of the parts, and company is gracious enough to allow the use of these facilities after hours.

I have a fair amount of the expensive parts I need from my old RV (Dometic reefer, new water pump, fantastic vent, maxxair vent, new toilet, magnum inverter)

I can get the solar I need for cost (we use them on equip trailers) and will probably use a set of dexter axles we have.

thx

CM

[HadEnough]

Comment is that gravity is your friend. Macerator pump is a complexity that solves a problem but that will break eventually.

Get different shapes for the tanks and put all freshwater and black water by the axles.

I'm picturing longer, flatter tanks situated so the longest stretch of the tanks are situated fore and aft.

This configuration balances all water over the axles, changes the location of the head to over the axle as well (move closet up front), eliminates macerator and is self baffling as they are long, skinny tanks situated "fore and aft" in orientation.

[Rvpapa]

Make real sure there is enough space in the second tank before you use the macerator. Might get real exciting and make a good U tube vid.
Art.

[Home_Skillet]

You can look at horse trailers with living quarters. They make use of a small space.

There are flat black water tanks that hold several gallons.
Google is your friend.

[mat60]

Will this build also cost you more than just buying a RV? I thought about a build a long time ago with a 8x14 carog trailer.

[Colonel_Monk]

Howdy. Yeah, I wish it was that simple. It's only a 14 ft x 7'4" wide inside area. I have already my freshwater tanks over the tandem axles, Dometic full size reefer over one tank and closet over the other.

If I put the bathroom in the middle then the freshwater tank would have to go to the front which doesn't solve the balance problem.

With the current floorplan I will simply be shifting the weight from the fresh water tanks to the waste tanks and more or less keeping the balance the same.

I do realize it's a pain, but seems doable.

Fact is, the idea of this whole RV project will seem unnecessarily complicated to some, it's certainly easier to just buy an RV which is why not many folks decide to build one.

I have specific wants that just aren't covered by traditional RVs. That said, there are downsides too to swimming against the current.

thanks,

CM

[donn0128]

Sounds like a whole lot of effort. Since your in the design stage, why not simply move the bathroom to the middle of the trailer?