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. 

Drain

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?

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67 Comments

  1. Brianna
    March 28, 2016 / 10:17 am

    Hi I am wondering what hose you used to connect from the gravity fill inlet to the water tank? I am about to do this on my own but haven’t been able to find any details on how to hook that part up, thank you!

  2. March 11, 2016 / 11:56 am

    Hey! Have you had any trouble with your drainpipes freezing when in cold weather?

  3. Michele
    January 10, 2016 / 10:40 am

    Hoping you guys can help us out with this: we’re building our tiny house now and have a utility shed that we’re hoping to use for a propane tankless water heater. It’s enclosed in the shed so doesn’t have open-air ventilation but also isn’t as well insulated as inside of our house (we live in Olympia, WA so it doesn’t get TOO cold here). Should we go with an indoor (that might need more insulation) or outdoor (that might need more ventilation) unit then???

    • January 11, 2016 / 4:59 pm

      Honestly I’m not sure… It all depends on which water heater you use, they all have different characteristics, though most do need venting. If it does freeze, you might want to commit to an indoor heater just to avoid the freezing problems, unless it self-protects.
      They will all be slightly different, you’d get better information contacting the manufacturers directly, or a plumber. We’re not quite water heater specialists just yet 😉

  4. Kevin
    January 6, 2016 / 12:19 pm

    Hi Guys,
    I am in the middle of my build (24′ cypress) for my 8 year old son and I. I was planning to use the same water heater you had but have not ordered it yet. So I am wondering if you liked your water heater enough to replace it with the same model or did you decide to try a different brand or model?

    • January 6, 2016 / 5:52 pm

      Yeah we would. The issue we had was human error and I feel that any other instant propane water heater would’ve failed before ours did. During the 3-4 weeks we were gone, the temperatures dropped down to the single digits and the pressure in our propane tanks dropped dramatically. The pressure wasn’t high enough for the water heater to light and protect itself against freezing, so it froze and broke. We replaced the part and ordered heated blankets for our propane tanks and it works like a charm now! If we wanted a tankless propane water heater for our next tiny house, we’d go with the same one.

  5. Brandon
    December 23, 2015 / 11:13 am

    Hello again! I’m on to plumbing and am considering the same tankless water heater that you have. Have you had any issues with it? I also noticed they make a wall vented unit and the floor vented. Do you have an opinion one way or another on that option? I have a Tumbleweed trailer so floor venting would be similar to your trailer. Thanks!

    • December 24, 2015 / 4:19 pm

      We just had an issue with ours because we left for a month and temperatures dropped to about 0 degrees F. Our propane tanks were pretty empty and with the temperature drop, our propane system didn’t have enough pressure to fire up the water heater so our heating element froze and busted. It wasn’t the water heater’s fault, it operated as advertised and tried to protect itself from freezing but our propane system lost pressure because of the cold temperatures did the rest. Any other tankless propane heater would’ve failed earlier. (we’ll probably write more about all this)
      We picked the floor vented one so we didn’t have to have a big hole in our wall.

  6. Ed
    December 21, 2015 / 10:03 pm

    I filled my 46 gallon water tank up and then ran water over to my tankless water heater. I have a pump that looks exactly like the one you are using so my set up seems a lot like yours. Now the problem. After running the water over to the heater, I let it get warm but after 20 to 30 minutes the temp was only around 67 or so. Why isn’t the water heating up faster than it is? and there seems to be low pressure although I am using a pump that is just like yours. Is the pressure suppose to be very strong? Thanks for any input you may have.

    • December 23, 2015 / 7:39 am

      Hi Ed, I’m not too sure how to help you with this. We just upgraded to this silent water pump but they basically have the same flow (3gpm vs 2.9gpm). We use 3/8 pex piping and our shower head is a 1.8gpm. Not sure about our sink faucet but it’s probably less than that. If you don’t have the exact same water heater, I really can’t help you. We live at 9,600ft so our water heater only functions at 60% capacity or so (that happens with all propane heaters). That means we only get about 50 degree temperature rise. To make sure our water is hot, we open the hot water only far enough for it to trigger the heater, the slower the water goes through the heater, the hotter it gets. If you open it full blast on hot, the water goes quicker through the heating elements and doesn’t heat up as much. Our heater heats up in 5-10 seconds. As for the 20-30 minutes after, I can’t speak for it. We only use hot water for a few minutes, all of our showers are short showers. The water heater might have a timer to protect it from over heating after a while.
      Good luck

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