RVs, Trailers, Boats, and the Human Support Systems They Use?

I've searched a bit and I know there's been varying discussion, but I can't even find the GRM article on living with an older RV. I found a thread, but it was more on shopping tips for the whole thing, when my question is...

I've got some probably silly ideas about building a flatbed-size camper with some other functionality, and I'm wondering where to look to learn about how all the aforementioned vehicles handle bathroom and kitchen stuff. Toilets, showers, water, cooktops, refrigeration.

Seems like boats and RVs would have some overlapping concerns, but also some differences (e.g. I don't know how many marinas have the same sorts of hookups that an RV might use at a campground). And I'm hoping for an overview that's broad enough to revisit why RVs use RV stuff and boats use boat stuff, and in what circumstances that might be up for consideration.

E.g. I don't know anything about either, really, but I have the impression that RVs pretty much always have a clean water tank and "used" water tanks, with I believe separation between sink water and toilet output? While boats I think more often use a composting toilet? Or other options?

I guess, what are the core basic things to know about the options available for having a self-contained camper if you were going to start from relative scratch?

Most newer rv spots have this style electrical hook up. It has receptacles:

30amp 120v

20amp 120v

50amp 220v

Old small hookups just have the 30 and 20amp 120v. If your going to use this trailer at a park, normally the electric box, in the unit, will be towards the rear of the unit. Your choice inside if you want 12v system. Solar is good for when you have no services.

RVs will have a clean water tank, a grey-water tank (optional but recommended) and a black water tank. Drink the clean water. Wash your hands with clean water and it becomes grey. Flush your toiled with grey or clean water and it becomes black. You then dump the grey and black tanks using gravity at the end of the week.

Boats will have a clean water tank (and hopefully a water-making system), a grey-water tank, a black water tank, and optionally an offshore-diverter valve where if you're far enough offshore you can have used water flow untreated overboard (kinda gross, but the ocean is a big place and fish already poop in it). When you get to harbor, you can have your grey and black tanks pumped out.

The systems are fairly simple, really, because cost is king and getting them built as cheaply as possible it what it's all about.

First off is the fresh water system.  There's a holding tank for fresh water along with a 12V water pump.  There's also a connection for "city water" with a check valve.  Some systems can use the city water connection to fill the fresh water tank while other use a separate fill tube.

From there, I think it's mostly pex these days, but the water runs to all the various faucets and the toilet.  Your water heater will have a bypass valve on the inlet, gas and/or AC connections for the heating element, and 12V power for control.  The outlet runs to all the faucets, as you'd expect.

Wastewater is divided into grey and black.  The sinks all use a regular P-trap drain that go down to the grey tank as does the shower.  The toilet dumps to the black tank and is just basically attached to the top of it.

The drains will come out of each waste tank, usually into a single outlet.  You'd put a valve for each tank before the common outlet.  Dump the black tank, flush it, then dump the grey.  If you've got sewer hookups, keep the grey tank open and the black tank closed so that you don't develop a pyramid - you want the liquids in the black tank to keep the solids suspended, as it were.

Propane lines are run through the coach and connect to the furnace (along with 12V), stove/oven, and water heater.  Sometimes there will be an external connection to attach a gas grill.  Propane tanks can be removable or bolted on, but travel trailers typically use portable ones.

I believe that all the AC service is single-phase 120V, even with 50amp service.  Basically you're getting a pair of 120V circuits.  I would wire for 50a and then carry adapter cables for 30 or 20 amp service, but be careful when adapting down because you can really heat things up.  Rooftop A/C units are 120V 20a each, typically.  Then you've got the regular outlets around for "stuff".  Your interior lights, roof fans, A/V equipment, awning motor, leveling jacks, etc will all be 12V and fed from the house batteries.  I've heard that using 4 6V golf cart batteries is spendy but awesome.  I just use a couple Autozone or Walmart batteries that are about $90 each and replace them every couple years, but I don't do a ton of boondocking.  If you have a generator, you can use a transfer switch or make it easy and just plug your RV's shore power cord into the generator outlet.  That way you never have to worry about backfeeding.

Absorption fridges are...  mostly adequate but use very little electricity from the 12V system along with not a ton of propane to keep things chilled.  They have to be absolutely level, there are some fire concerns if they're not level, and they aren't the best performers in the world.  Your other option is a residential fridge, but you're going to be stuck using AC, so they're not a great choice if you intend to dry-camp and don't want to constantly listen to a generator.

There was a time when boats had their wastewater systems just dump straight to the outside and they'd use a macerator to, uh, "process" the, er, "solids" as it were.  Then for a while they had holding tanks that you'd use close to shore and a switch to just send it all out when you weren't.  I don't think they're allowed to have that option anymore, though.  I have heard of people using a macerator to be able to pump their tanks at home through smaller hoses when a sewer hookup (aka clean-out) isn't available in the driveway.

In reply to wae :

Very correct on the 50A service on (in?) RVs. No 240V devices in an RV. Someone could hack one, but wouldn't be proper. 
Note: some rv hookups are only using the 50A plug. Ya have to use an adapter to plug a 30A only rv cord into. Technically not "legal" to code (you end up with wire and plug rated for 30A, on a 50A breaker) but I've seen it, and done it. 
 

In reply to 03Panther :

Explain?

Why would it be "illegal" to plug a lower amperage device into a larger amp breaker?  

I don't think the electrical code applies to anything after the final termination (the park panel on the pole)

Help me understand

In reply to Jesse Ransom :

Marina's have to pump out waste water from the boats 40 gallon stainless steel holding tank.  While campgrounds dump waste  from a typically "plastic"  holding tank of larger size by gravity. 
  Filling the 80 gallon water tank is a matter of  a garden hose in both applications.  Really not drinkable.  

I thought the problems only really came in to play when you were going the other way - plugging in a 50A coach to a 15A line, for example.  I know that I managed to melt a handful of 30A to 15A adaptaters by trying to run the rooftop air in my driveway.  Once I stopped that foolishness, I stopped needing to replace the shore power plug on a semi-regular basis.  I'm a slow learner.  But, for example, the lamp that I plug in to my 20A circuit here at home doesn't have a #12 cord on it and if I tried to draw the full 20A it would probably turn to ash almost instantly.  There's nothing bad or unsafe about that, though, because we know what the current draw is for that device.  When I plug my 30A coach into 50A service, I know that the mains on my side blows at 30A so I never have to worry that I'll overdraw the adapter pigtail.

In reply to frenchyd :

It's a potable water tank. It's supposed to be filled with only a potable water hose. 

In reply to wae :

The 50A breaker is to protect the wire that is permanently installed from being overloaded (buried in the ground). 
 

It doesn't protect the pigtail. 

frenchyd said:

  Filling the 80 gallon water tank is a matter of  a garden hose in both applications.  Really not drinkable.  

Point of order:  You need to have three hoses on-board.

White: drinking water.  Pair that with a good filter and a pressure regulator.  Use it without the regulator to fill the freshwater tank, use it with the regulator to hook in to city water to prevent blowing out your lines if something weird happens.  This gets stored in its own container in a different compartment than the other hoses.  Never connect to anything but a known good potable water supply.  Run a little bleach through in the springtime to make sure it's cleaned out.  If you camp in cold weather, get one with the little heating wire in it.

Green: water water.  This one is optional but good to have.  We have a misting fan that we break out sometimes and we use this hose to feed that or to do anything that you'd use a hose for in your backyard (keeping campground etiquette in mind, of course).

Black: flushing water.  This is kept in its own container, preferably with the other grey/black tank draining supplies.  Handle with gloves and wash hands immediately after use.  Never use for anything else but to flush the black tank.  Never connect to anything but a designated and marked non-potable water supply.  Ever. 
 

Also, you should sanitize the freshwater tank when you de-winterize (or once a year) just to keep things clean.  Replace that filter on a regular basis and make sure that no water goes into the tank that doesn't pass through your filter (and your white hose).  As long as you do that and keep your hoses straight, there is absolutely no reason that the freshwater contents won't be potable.

In reply to SV reX :

Ah, so thinking more about it then, the risk would be if something between my breaker and the pigtail shorted out, it could overdraw that portion of the system by 20A before the campground breaker would pop.

In reply to wae :

A dead short is not an overdraw. 
 

Your camper only has the capability of drawing 30A. It's not gonna overdraw. 

In terms of the water systems- packaging is going to be the first cost input. If you can fit simple shapes, large tanks are cheap. If you require an odd shape- small tanks are very expensive. 
 

There are some good on line sources for tanks, btw. Enough to drive you nuts when trying to find the right ones. 
 

As pointed out- PEX all the way. 
 

imho, if you want real off grid capability for cheap, a propane based system is easiest. While it's possible to do electric, the additional solar plus batteries is expensive and complicated. 
 

That being said, I would suggest keeping an open mind for a 12v fridge- with a modest solar panel, and real 100ahr battery- it can run for a couple of days wo recharge and the bonus is that there is more volume for the footprint than absorption fridges. Let alone the design around running a small flame all the time- that has to be vented. 
 

Still, there are a ton of vloggers out there on the U of Tubes to get some great ideas how to deal with everything. 

One more thing- for electric- there are some great RV centric breaker systems out there- that have the 12v and 120v systems incorporated in one. Very cool systems. If you plan hard what you will use- you can match a system easily for number of circuits for each 12 and 120v. 

SV reX said:

In reply to 03Panther :

Explain?

Why would it be "illegal" to plug a lower amperage device into a larger amp breaker?  

I don't think the electrical code applies to anything after the final termination (the park panel on the pole)

Help me understand

Because the 50A is 240v and the 30A is 120v.  You would be using an adapter that only uses one leg of the 240v service, so depending on whether or not the breaker is double-throw or single, it won't properly protect the circuit.

In reply to Jesse Ransom :

Check out some #vanlife builds on YouTube. We spent about a year watching all we could find, thinking we were going to convert our E250. Then when our RV sort of fell into our laps we were better prepared & also realized it was a far better idea to buy it & deal with its problems, then spend a couple years figuring out all the details to convert our van. 

Most others have covered much of it.  You'll want to familiarize yourself with RVIA standards.  That's recreational vehicle industry association.  They are kinda the "building code" for RVs, but they aren't a governing body, more of a union of best practices.  It's not like a house that uses copper plumbing and romex, the materials used have to be up to the flexing and vibration of road use.  Once you sort out the plumbing and electrical, the rest can be residential-grade like cabinets, floor coverings, etc.  Just be aware that most everything needs to be bolted down, like tables, chairs, etc.  That's why most RVs have dinettes instead of table and chairs.  Walls in RVs are usually some kind of thin ply like luan with a wallpaper.  Drywall obviously wouldn't survive the flexing.

Camping World is a good (but very retail) source for anything you need.  Etrailer and Recpro are a couple others.

Depending on how you want it, electrical systems are a bit complex.  Fortunately there is a magic box you can use.  It's a combination 12v converter, breaker/fuse panel, and regulated power source.  It distributes 120v when plugged into shore power and provides 12v charging to batteries.  Most things in an RV are 12v or propane, but 120v outlets are only fed from shore power unless you find some way to incorporate an inverter.

If you add propane for a fridge, stove, or furnace, do your homework on DOT laws.  There are specific regulations on how much you can carry and when the tanks can be open.  For instance, if you have portable tanks you have to secure them a certain way and they can't legally be open while towing (although most people do).  If you have a permanently mounted tank, it can be open but it also has specific requirements for how it's attached.

In reply to Curtis73 (Forum Supporter) :

That would be correct if the voltage varies. 
 

But if the voltages are similar, a 30A RV can be plugged into a 50A outlet. 
 

In reply to SV reX :

Today I learned.

I was always told that you can't put a draw on one leg of a two leg setup.  Like if I were to add a 120v 15A outlet on my 240v A/C circuit that would be a bad thing, but I won't disagree with someone of your much-greater experience.

alfadriver said:

In terms of the water systems- packaging is going to be the first cost input. If you can fit simple shapes, large tanks are cheap. If you require an odd shape- small tanks are very expensive. 
 

There are some good on line sources for tanks, btw. Enough to drive you nuts when trying to find the right ones. 
 

As pointed out- PEX all the way. 
 

imho, if you want real off grid capability for cheap, a propane based system is easiest. While it's possible to do electric, the additional solar plus batteries is expensive and complicated. 
 

That being said, I would suggest keeping an open mind for a 12v fridge- with a modest solar panel, and real 100ahr battery- it can run for a couple of days wo recharge and the bonus is that there is more volume for the footprint than absorption fridges. Let alone the design around running a small flame all the time- that has to be vented. 
 

Still, there are a ton of vloggers out there on the U of Tubes to get some great ideas how to deal with everything. 

That's really good to know about 12 volt refrigerators.  Are the 12v A/C  as good?   ( and cheap?)    My ultimate goal is to convert a Semi into a race car hauler/camper. 

Technically you can drink water out of the freshwater system in an RV.

We do not.  We use bottled water or a smaller 5 gallon "drinking water" container for drinking.  

We still do the 1 cup of bleach sanitization thing in the spring after we drain the winterizer, however it's just as easy to keep the much easier to sanitize after every trip or whenever we feel like smaller drinking water tank around.

I wouldn't worry about using a plug adapter on a 50amp circuit.  That exact panel when you plug into the "30Amp" breaker is already going to only put the 110V on 1 leg of the supply to that panel.

Our camper uses a "2 way" ammonia evaporative fridge.  I like it.  It has very low power and gas consumption.  Like it runs for WEEKS on a gallon or two of propane, and once it's lit energy use is a few LEDs.  The "2nd" way on it is 110V.  I've replaced the control board with a Dinosaur Electronics control board (These guys make control boards for almost every RV appliance and their stuff seems to be great).  That said it sometimes struggles to realize it can go into 110V mode and shut off the gas supply.  I would care if it had higher gas consumption.  We've not had issues with it being mad about being "out of level".  Basically if the RV is level enough to sleep comfortably the Fridge works fine.

In reply to Curtis73 (Forum Supporter) :

ALL 120v 15A outlets are essentially tied into 240v. The panel is 240v. A 120v circuit is just pulling off 1 leg of the 240v. 
 

If a 240v circuit has a neutral leg (4th wire), you can have 120v. 
 

HOWEVER, that doesn't mean anyone should be jacklegging together jumper pigtails that mix stuff up. 
 

I think most RVs are 120v. There is such a thing as a 50A 120v plug. But you may be right on this. 

My post was in response to earlier ones that suggested plugging a 30A into a 50A outlet was a bad idea SOLELY because of the amperage difference. That's incorrect. 
 

But a voltage difference would change that answer. 

Curtis73 (Forum Supporter) said:

In reply to SV reX :

Today I learned.

I was always told that you can't put a draw on one leg of a two leg setup.  Like if I were to add a 120v 15A outlet on my 240v A/C circuit that would be a bad thing, but I won't disagree with someone of your much-greater experience.

Oh, and specifically on your 240v AC outlet...

If it's an older 3 wire plug, you can't have 120V. There is no neutral. 
 

If it's a newer 4 wire plug, you can technically have 120v, if it's done right. 

SV reX said:

In reply to Curtis73 (Forum Supporter) :

HOWEVER, that doesn't mean anyone should be jacklegging together jumper pigtails that mix stuff up. 

So you're saying the 220V welder extension cord my dad built that had 2 110V legs that you had to find outlets on circuits wired to opposite legs of the panel was a bad idea?