Tiny House Plumbing – Water, Water, Everywhere!

Marc Bilodeau/ Building, Planning, Tiny House

Every area in the tiny house provides its own challenges and sense of accomplishment. However, there are some milestones that feel like a huge leap forward towards completing the build. The first milestone was the roof, then it was the lights. Now, it’s the wonder of tiny house plumbing. There is actual running water! It’s very exciting.

It sounds so trivial as we take plumbing and running water for granted. It took building a tiny house and assembling the pipes one by one to fully appreciate this modern wonder. However trivial a few pipes look, there was a lot of planning and assembling.

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Planning the Tiny House Plumbing System

How hard can it be to put together a tiny house plumbing system? It isn’t really that hard to assemble, but it take a lot of time and planning. Since I’ve never put together a plumbing system before (like many system in the tiny house), the first place to begin is to do some online research.

Planning is critical as this isn’t something that can be thrown together on a whim. Some key questions to ask are:

  • Where will the pipes go in the walls?
  • How will fresh water come into the tiny house for both on-grid and off-grid use?
  • How will gray water drain from the tiny house?
  • What types of pipes will I use?

Once those questions have answers, a plan can take shape. I put together my plan in Google Slides that shows how all the pieces would come together.

Tiny House Plumbing
A plumbing plan of attack. Look at the Photo Album for bigger images.

Next, I counted all the pieces in the tiny house plumbing system and purchased the necessary components.

Assembling the Tiny House Plumbing System

Overall, I expected it to come together quicker than initially planned. However, the small space under the counter required some adjustments to fit every core component.

Tiny House Plumbing assembled
The interior of the tiny house plumbing system

For the most part, the initial plan and the final layout are very close. However, there are a few differences:

  • The SHURFLO Pre-Pressurized Accumulator Tank is mounted on the wall instead of the floor
  • Now, there is a shut-off from the output of the hot water on the propane water heater
  • The shut-offs for the shower are before the Ts near the LUNOS instead of above the shower

The fact there were only minor changes shows that the overall planning process anticipated and addressed many of the potential issues ahead of time.

Pressure Testing the System

The tiny house plumbing system looks impressive. However, does it leak at any of the joints? The only way to test that is to do a pressure test of the system.

Thankfully there are some guidelines on how to do a pressure test with water and air. For example, the International Residential Code outlines ways to do proper testing. However, it can vary regionally so it’s important to check local rules and guidelines.

One of the advantages of using PEX is it’s flexible and can bend around some corners. This helps reduce the number of joints and possible points where leaking can occur.

There are two inlets into the tiny house for on-grid and off-grid use. The differences between the two is the on-grid connection goes directly to the water filter. The off-grid option comes from the holding tank, flows into the pump, through the accumulator tank, and then into the filter.

The off-grid testing was done by increasing the pumps pressure to the maximum capacity and having it pump water to fill the pipes. Both sinks and the shower are off during this test. After 15 minutes, each joint was visually examined and touched for the presents of water. Although it was still plugged in, the pump remained off during that time which is a good sign there are no leaks.

The on-grid tests are done in a similar manner except it requires connecting to the on-grid connection and shutting off the valve from the accumulator.


Greywater is all wastewater from a household except for the wastewater from toilets. Some examples of greywater include sinks, showers, baths, washing machines, and dishwashers. Since this tiny house uses a composting toilet, all wastewater is greywater. There is no blackwater.

Tiny House Plumbing Greywater pipes
Greywater exits through these pipes underneath the tiny house

Each drain from the shower to the kitchen sink flow into a 2″ PVC pipe to the main drain. From the main drain and the Fill Tank Drain, an adapter will redirect the water for proper deposal. The main pipe has a slight downward angle to keep the water flowing toward the main drain.

Tiny House Plumbing Greywater drains

The last task is to install hangers that supports the main pipe. This will keep the main pipe from shifting while the tiny house moves to different locations.

Some areas allow for the use of greywater to water plants or dump freely onto the lawn. However, check local laws first. If these are valid uses greywater, it’s important to use environmentally safe soaps and to not drain anything harmful.


With all the plumbing in place and the pressure test complete, water is available from the kitchen sink, bathroom sink, and shower.

Tiny House Plumbing with Kitchen Sink, Shower, and Bathroom Sink

However, there is no hot water in the tiny house until propane lines are installed to provide gas for hot water and cooking. In the meantime, one certainly can enjoy a cold shower or a glass of water.


The tiny house plumbing system provides fresh water for cooking, living, and cleaning. Thankfully, it is possible to DIY if you choose to do so with careful planning. With the internet at our disposal, it is fairly easy to put an effective plan together by reading, watching videos, and researching.

Overall, this DIY adventure took 29 hours between two people and many more trips to The Home Depot than usual. Regardless, it is one more milestone complete, and one more step closer to finishing the tiny house.

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