Hydronic Recirculating Shower and Radiant Floor Heat Rough Draft

New here, first post. My mind is a flurry of ideas in the planning phase. In the market for a low mileage used gas promaster 159, been beat to the dealership 3 times already in 3 weeks since looking.

I am seeking advice from you all about my rough draft idea of a hydronic recirculating shower and radiant floor heat. Attached is a rough diagram.

Any thoughts? Am missing anything? Will this even work?


Greetings & Welcome!

I’m having a hard time trying to wrap my head around why you want to overly complicate such easy things to accomplish…

Most camping has a 2 week limit on how long you can stay. I carry 2x 7 gallon jugs of water, which will last me 2+ weeks, even showering daily, and not recirculating it. I’m more likely to run out of groceries before I run out of water. I can also refill from any stream or lake and filter it if the need arises.

Heating is also pretty cheap and easy.

I like to keep everything as simple as possible. The more complicated it is, the more complicated your problems are. If my heat or shower has problems, I can repair or replace them very cheaply almost anywhere. You’ll learn to appreciate such advantages.

It is often more about what is practical, than what is possible.


"Beat Murphy's Law with a KISS! (Keep It Stupidly Simple)" ~ Van_Dweller

1 Like

I’ll second what Van Dweller says. KISS (Keep It Simple, Stupid!) is far superior to complex and interconnected. If one thing goes down, then that’s all you have to worry about, and you’ll more likely be able to fix it.


So I’ve got two responses here…

First Response

Cool idea! My electrician buddy that is going to be helping me with my Shuttle Bus was actually telling me about something he designed that is very similar. He was doing a “for fun” build schematic with his Engineer Father, so they really went all out like you’re thinking here, really putting the latest tech and what not into full use.

If it’s something you’re really passionate about, don’t mind spending the money, and really want to just see if you can make it work… Then go all for it man!

As for the design itself…

If you have a Grey Water Tank, then how is it recirculating? Because using a primary and secondary tank on a recirculating system just means needing an extra pump when you could just drain to the original reservoir then push through the filtration system before reusing the water. So I’m not sure I understand that fully here in your design.

Also, your “UV filter / 3 Stage Filter”, if you are draining/pulling from the same shower tank (your 5-gallon tank), then those filters would have to be moved inline after the drain but before recirculation. Shower, Filter, Recirculate, Heat, Shower, Filter, Recirculate, Heat…

As a Certified Backflow Inspector, I’m going to tell you right now, I would never connect a shower line to a drinking line. Not in a recirculating system, because Youtube and all that crap never tell the truth about recirculating systems because it’s gross, but I’m gonna call you out on it right now. When you get your stank ass in that shower and scrub your butt, you are going to be putting SOME level of fecal matter into that line. I don’t care how clean you think you are, you are going to be getting something into that line. Keeping dirt and whatnot out of the line could be achieved by regular filtration, the UV is meant to be a barrier to bacteria that manages to make it beyond that base filtration.

So the role of all the extreme filtration is literally to minimize that hazard as much as possible. The first line of defense is to remove as many particulates as possible, the second is to neutralize any contaminants through UV filtration that will hopefully destroy the bacteria to make it inert. In truth it’s actually still there, the UV light just makes it so that it is no longer functioning by destroying the DNA strands.

So actually that’s another thing, you are going to want to move the UV filter after the staged filters. The fewer particles/objects moving through that filter the better chance of it catching any and all bacteria to nullify it.

Now, just to be 100% clear, these are just my opinions based on my own experiences. Hopefully though, something I’ve suggested helps you better visualize your own goal and desire.

Second Response

You aren’t going to need that. A Buddy Heater and accepting the fact that your floors are going to be cold some days are more realistic choices, and cheaper!

So unless you really just want it, I wouldn’t even bother. I actually have the pieces and components for a similar design but with a different goal in mind. I just wanted to be able to take showers that lasted as long as I wanted and to be able to take maybe 5-10 in a week off the same 15-gallon tank.

This is my design,

It’s significantly less complex than yours, but still, even my design is a solid “95% over-engineered”. Honestly, if I hadn’t already purchased the pieces (7 months ago) I wouldn’t even bother with all this crap.

Now, it’s not just “being cheap” or sticking to “KISS” (although sticking to KISS is really always a great idea), I actually have a very practical reason for saying you probably won’t need all that.

If you were in the city, you’d have ready access to water, so wouldn’t need to “make the most” out of what you are carrying.

If you are planning on Boondocking, well unfortunately the rules and availability of that is changing drastically due to COVID. Apparently, a HUGE influx of people have been hitting the National Parks / Forests / BLM Land / Etc due to being out of work or just taking time off due to COVID. Which is great, that land is literally there for us to take advantage of.

But, apparently, these assholes are “literally” “taking advantage”. They are destroying the land, the landmarks, as well as leaving incredibly large piles of garbage. Every day I’ve seen at least one article about a park/forest/etc closing or changing their rules due to people being dirtbags. The number one rule change has been that you can only stay for up to a week now, whereas before the standard was largely 2 weeks with exceptions.

So if you are only able to boondock for a week before needing to move, there just isn’t any need to conserve as much as a recirculating system would potentially provide.

Again, just my opinion, but just want to give you an honest one. :smile:

Wow, first, thanks for the awesome response!

Extended boondocking is not a major goal. The main goal of the project is comfort. A hot 30min shower before bed is a ritual for my wife and I. I am also very interested in the challenge of getting it all to work.

To address some of your points:

The grey tank doesn’t recirculate. I do not want shower water, even filtered, in my clean drinking and sink lines.

I plan on having a separate shower water tank that can recirculate or empty to the main grey tank.

The intent of connecting the clean line to the recirculating line was to be able to take clean water showers when the shower tank is empty, connected to city water, or as a final rinse. I am very interested in your opinion on this. I intended on adding a check valve between the systems to stop shower water from entering the clean side. Do you think that this is not adequate to stop the backflow?

Agree on uv light after filters, I believe that is how I have it drawn.

I was originally looking at tankless water heaters. Then I stumbled on gasoline hydronic heaters, which is more efficient and doesn’t require inverter power. Which opened the flood gates to ideas of parasitic heating from the engine coolant, forced air heat, and radiant floor heat. Since I am going to have the hot glycol anyway for hot water, might as well use it for cabin heat too.

Your design is very similar to the shower side of my design. Just sub out the tankless for a hydronic heat exchanger and add in a couple of valves to be able to shower with clean water.

On covid impacting boondocking - I hate people. I wish people wouldn’t ruin a good thing for the rest of us. The way I see it, I will always be practicing “leave no trace.” So I can, in good conscience, know that my impact is minimal and plan to stay out as long as I see fit. I will absolutely give way to other campers, if they are present, once my stay is over the allotted time. I will also respect any ranger’s direct orders or suggestions.

As long as no one is vying for my camp spot, and I act responsible to the land, I do not foresee any problems in occasional extended stays. That being said, I do not plan on boondocking for longer than a week anyway.

1 Like

I don’t believe covid has much influence on BLM land that I can see, the number of people there or the amount of trash left. That’s not a new thing and it was certainly around before it.

From personal experience through covid. We haven’t had a single ranger even stop to question us and we certainly stayed in one spot for about 1 and a 1/2 months this summer. We went all over the PNW and north west without issue. We are also very considerate of the pack it in pack it out rules as many people are. Of course there are always going to be those types that suck and ruin things.

As far as vying for a camp spot. Pack a tent and pitch it if you want to keep yours. Everyone else does. And it lets you drive away and return.

I for one will never install a grey water tank. Pumping out is one of the grossest things I’ve ever had to do in my life. Not to mention the smell.

Maybe just try minimizing your foot print. Take low pressure showers and use products that are not harmful to the environment in the process.

1 Like


Oh yeah, if comfort and the challenge of it are the two primary goals, then I say go for it! Haha, I’ve got a few “over the top” comforts myself that are less “necessity” and more “Two is one, and one is none” mentality. :laughing:

Okay cool, yeah I lost the flow somewhere in your chart and thought I was seeing connected drinking and showering lines, I’m not even saying that it couldn’t be safely done so much as I just would never take the risk personally, haha. I also see what you mean about the UV light, originally I had thought the flow was heading the other direction but now I understand the intent.

The check valve will stop backflow provided one of two factors are in play,
A - That you have active pressure pushing in the intended direction.
B - If it is closed, it will prevent all flow.

But if you hit scenario C,

C - No pressure and the valve is open. (AKA - Human Error)

Any number of issues could “potentially” reverse the flow and possibly push contaminated water back into drinking water.

I seriously doubt you would do this, but, even something as silly as the grey water tank being mounted higher than the clean water tank could potentially cause backflow. I can’t think of any reason why you would do that, but my point is even something that small. A clog somewhere with pressure from somewhere else down the line, with that check valve open, could potentially cause backflow.

I mean, are these scenarios likely? No, probably not. But would I want to risk dysentery? No, definitely not. :laughing:

You could put a double check valve assembly somewhere in the line that would greatly reduce the risk of backflow. But that’s kinda silly to be honest, and you’d have to have it checked annually (not really, but checked every now and again) to make sure it was still working properly.

Again, I’d just like to say again this is all personal opinion, and in no way “professional advice”.

My solution was just to have two different fill points for drinking and showering water with this guy,

(Not an influencer, don’t get money from link clicks or any BS like that)

That way I can hook up to a hose or whatnot while parked at friends/family, but also don’t have to worry about any cross-contamination. For my drinking water, I have a 55 gallon hooked to the sink (or will soon anyway) and then have a “Travel Berkey” for the actual filtering.

Hope any of this rambling helped somehow! :smile:

Oh awesome, all these news articles were starting to worry me.

Yeah… I’m really trying to avoid that myself. They are gross. DX


Hills, acceleration, braking, and cornering could also affect water flow directions…


"If you prepare for the worst, every thing else is easier." ~ Off Grid

1 Like