Tiny House Plumbing

Tiny House Plumbing

Plumbing is probably one of the scariest parts of any build, especially when you have zero construction experience (like me). I’ll take you through my Tiny House plumbing, but keep in mind that there are several ways to do this depending on your preferences.

One thing to note before we get started: my set up is simple. I only have one shower and one sink. I do not have a washing machine, dishwasher or bathroom sink. My toilet is a waterless compost toilet.  My system is set up to be on-grid or off-grid and to be water conscious.

Alright, are you ready? Let’s dive into Tiny House plumbing!

To understand this article, you’ll need to learn the following terms: off-grid, on-grid, fresh water, greywater, and black water. Don’t worry, I’ve defined them all below.

“Off-Grid” VS. “On-Grid”

What do these terms mean? Off-grid means that you are NOT connected to city water and that your system is self-contained. You might be off-grid when dry camping or parked on a  piece of land without city connections. On-grid is when you are connected to city water, such as in an RV park.

I have both off-grid and on-grid options in my tiny house, which I recommend for flexibility in parking. Of course, if you will always have a city water connection, having an off-grid system is not necessary.

First, let’s discuss fresh water for both off-grid and on-grid. 

Fresh water is the water you use for drinking, cooking, showering, toilet, washing dishes, etc. 

My “Off-Grid” fresh water system

First, let’s talk about my off-grid fresh water system. For water storage, I fill a 46-gallon water tank, which is secured under my kitchen counter. I fill this tank by connecting an RV drinking hose (or carrying jugs of water) to my water inlet.

The average American uses between 80 -100 gallons of water a day, so it’s good I am not “average.” I use about 10 gallons of water a day. When I am off-grid, I fill my tank every 4 days.

My Water Inlet

Now that we’ve gotten water into the house, how does it work?

To heat the water, I have a tankless propane water heater, which is extremely efficient. Read more about it here. For off-grid water pressure, I use a water pump. The water pump runs on 12V and the water heater requires 12V to spark and to protect itself from freezing. My house is wired for 110, so I have a 12V converter to run these appliances. These elements can easily be powered by a gas generator or solar power when off-grid.


Our 12V Converter

My “On-Grid” fresh water system

When I am “on-grid” (connected to city water) I simply connect my RV drinking hose to the supplied spigot and there’s no need to use my water tank or pump. In the winter, I need to use a heated hose and insulated spigot. More on Tiny House winterization here.

Once the city water pressure was so strong it actually broke my inlet! Since then I’ve replaced my inlet’s plastic fittings with brass ones, and I’ve purchased a pressure regulator.

The plumbing choice for tiny homes is PEX. It’s DIY friendly and lightweight. You will need the PEX piping,  crimping tool, brass elbows and fittings to do the jump yourself.

As a note, I also use a low-flow shower head to conserve water. I have not found this to be a problem when washing my hair. I’ll also mention that the water pump I initially bought (pictured below) can be a bit loud. I ended up replacing it with this more expensive and quieter water pump. Both work fine, but if you want the quieter version, go with the one I just mentioned.

Water pump

Greywater is the water that drains out of sinks and showers

Greywater is not necessarily waste. I use biodegradable products for my soaps, shampoo, conditioner, lotions, etc. My greywater consists of these soaps, my body oils, and food products diluted with fresh water. If I had my own land, I would create a drainage system to use my greywater for irrigating my garden, similar to Art’s tiny house system. It’s a great way to recycle!

When I’m off-grid, I use a portable greywater tank. If I’m on-grid, usually at a campground, I connect to the sewer system with an RV sewer hose.

grey water tank

Portable greywater tank

As with fresh water tanks, greywater tanks come in all shapes and sizes. Mine is only 15 gallons, so I have to dump it once a day. I’m actually glad it’s small because I can empty it myself (it weighs almost 100 pounds when full).

How to dispose of greywater when Off-grid

Where I dump my greywater really depends on my location. If I’m on at a national park, I dump it at the allocated dump stations. Dump stations are also sometimes available at rest stops. If I’m in a residential neighborhood, I dump my greywater in the nearest sewer drain or I ask my host if I can use it to water their grass. If it’s raining outside, that’s a good time to dump! Any smelly food product is easily washed away by the rain. Consider it this way, most people wash their cars in their driveway. The soaps they are using have chemicals that are substantially more harmful than my greywater.

*As a note, dumping greywater is not legal everywhere. Research your location and use your best judgement. 


Greywater drain and portable tank

Black Water is the waste water from a toilet

I don’t have this because I use a composting toiletNo, it doesn’t stink. Read my full review.

I did plumb a fresh water line for a possible flush toilet addition in the future (in case I sell my house one day). You can see that above my toilet in the below photo.

toilet thgj

Nature’s Head composting toilet

Dumping black water

This is a very unenjoyable process. You will need to install a black water tank on your tiny house, and then pay to have it pumped out or drive it to a dump station and do it yourself. You can also bypass your black water tank and connect to the sewer via an RV sewer hose. 

Guess how you know when it’s time to dump? Smell….

I’m told that the average full time RVer has to dump their black water every two weeks. I dump the solids in my composting toilet every 3-4 months. I don’t have much more to say about black water because I don’t have it. My suggestion is to go waterless with a compost toilet. 

YOUR TURN: How did you handle Tiny House Plumbing?



  1. Alexis
    November 28, 2016 / 1:49 pm

    Hello! How did you attach the grey water tank to the bottom of your house? I’m building an expedition vehicle and am having trouble finding a company that can recommend a product designed to be attached to the underside of the vehicle. Thank you

    • November 29, 2016 / 8:51 am

      Also, note that the portable grey water tank is not attached to the trailer. It’s on wheels so that it can be towed away and dumped easily. If you are looking to attach a tank to the underside of your vehicle, check out RV forums for their recommendations.

    • February 11, 2017 / 3:40 pm

      Hi! I didn’t attach it. I have a rolling, portable greywater tank. When I move around I simply throw the tank in the back of my truck. I think it is better this way because if the greywater tank was attached, I would have to drive my tiny house to the dumping station every time I wanted to dump it. I’d rather disconnect the greywater tank and roll it to the dump station.

  2. November 28, 2016 / 10:24 am

    How did you attach the free watertankto the bottom of your home?

  3. jennifer crum
    September 14, 2016 / 8:49 am

    i have a couple of questions about water going out of your house, i can see the PVC pipes under the trailer,

    1- are your sink and your shower connected to the same drain?
    2- is the drain all the way through the floor? through the flashing?
    3- how do you keep everything from freezing ?

    we live in Northern Vermont and temps can be -20 for days

    thank you
    we are about to build, and I am confused about setting up the plumbing drains

    we will have to be self contained in order for us to be legal where we want to park. The septic company has agreed to supply a temporary tank and come pump that out whenever we need, so will not have to deal with the grey water

    thank you,

    • September 19, 2016 / 8:46 am

      1). Both the sink and shower flow into the same PVC pipe under the trailer.
      2). Yes.
      3). In the winter we skirt our tiny house, which helps a lot. You can also wrap heat tape our use heated hoses. We used out interior water tank for fresh water in the winter and would only fill the tank when the weather was warmest. Our spigot froze a few times. Our water heater froze as well. Explore this website for more cold weather prep, tips and stories. We’ve written about it in detail.

      Good luck on your tiny adventure!

  4. Devon-Ann Gilligan
    September 8, 2016 / 10:44 am

    Is your tiny home RV certified? If so, was it overly difficult to certify for plumbing/gas lines?

    • September 13, 2016 / 9:16 am

      Our tiny home is not RVIA certified. It is classified as a Rec Trailer. To be RVIA certified, you need be a manufacturer.

  5. Chris Williams
    June 27, 2016 / 10:16 am

    Quick question, are your freshwater drain tanks and grey water lines different lines or are you using the same line? Thanks!

      • Chris Williams
        July 22, 2016 / 11:37 am

        Thanks! A second quick question. I’m looking for the same 90″ you have that goes into your tank. Male threaded on one side, the other side connects to the vinyl hose. Do you remember what this is or where you got it? Thanks!

  6. June 10, 2016 / 12:57 pm

    Hey! Do you have p traps, if so where are they? Do you have grey water from shower and sink drain from same outlet? What did you use to attach the plumbing underneath the house? Did you do that yourself or hire out? It looks very legit underneath and solid, have you had any issues with clearance because of piping being under trailer? Thanks a lot you guys are awesome and huge help along our own journey!


    • June 10, 2016 / 10:36 pm

      Our P-traps are under the sink and under our elevated shower (so the p-trap is in the insulated part of the house). Grey water goes to the same place. Plumbing was done by a plumber and by Guillaume. And we’ve had no issues with the clearance of our plumbing 🙂
      Thanks for your kind words and glad you like our project!

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