So, you’re taking the plunge into tiny house living. It’s an incredible adventure, a chance to simplify and live more intentionally. But let’s be honest for a second—the romance of a minimalist lifestyle can hit a snag pretty fast if your shower doesn’t drain or your toilet… well, you get the picture.
Plumbing in a tiny house isn’t just a scaled-down version of a standard home’s system. It’s a whole different beast. You’re dealing with limited space, mobility, and resources. Getting it right from the start is, frankly, non-negotiable. This guide will walk you through the crucial decisions, from your water source to what happens after you flush, so you can avoid the nightmare scenarios and enjoy the freedom you signed up for.
The Big Question: On-Grid vs. Off-Grid Plumbing
Before you pick a pipe, you need to pick a path. This fundamental choice dictates everything else.
The On-Grid Route: Familiar Comforts
If your tiny house is parked on a foundation with access to municipal services, your plumbing can be very similar to a traditional home. You’ll hook up to a city water line and sewer connection. It’s convenient, offers unlimited (theoretically) water, and requires less upfront planning for water storage and waste disposal.
The downside? You’re tied down. And you’ll still have monthly utility bills, which can defeat one of the financial goals of tiny living for some.
The Off-Grid Path: Ultimate Freedom
This is where things get interesting. Off-grid plumbing means you’re your own utility company. You’re responsible for sourcing your water and dealing with your waste. It requires more equipment, more planning, and a bit more vigilance. But the payoff is total location independence.
Here’s the deal: most tiny housers aim for some version of off-grid capability, even if they sometimes connect to services. It’s all about flexibility.
Your Water Source: Filling the Tanks
For an off-grid or mobile setup, you need fresh water. This usually means storage tanks. The size and placement of these tanks are huge considerations for tiny house plumbing systems.
You’ll typically have a primary freshwater tank, often placed in a heated underbelly or storage compartment. Size matters here—a 50-gallon tank might last a single person 4-5 days with careful use, while a 100-gallon tank offers more breathing room. Remember, water weighs over 8 pounds per gallon. A full 100-gallon tank adds over 800 pounds to your tiny house, a critical factor for your trailer’s weight rating.
Filling options include:
- Garden Hose Hookup: The simplest method when you’re at an RV park or a friend’s house.
- Water Pump and Hose: For pulling water from lakes, streams, or well points (always check local regulations and filter/treat the water!).
- Water Delivery Service: Having a company fill your tank, much like for a rural home.
Getting the Water Moving: Pumps and Heaters
Gravity is great, but in a tiny house, your water tank is likely below your faucets. You need pressure.
Water Pumps: The Heart of the System
A 12-volt DC demand water pump is the standard. It’s energy-efficient and kicks on only when you open a faucet. The sound—a distinct *buzz-zz-zz*—becomes the soundtrack of your tiny house life. You’ll want to install a small accumulator tank alongside it. This tank holds a bit of pressurized water, which prevents the pump from cycling on and off rapidly every time you barely adjust the tap. Trust me, your sanity will thank you.
Water Heaters: The Luxury of Warmth
Nothing ruins a morning faster than an ice-cold shower. For tiny homes, you have two main contenders:
- Tankless (On-Demand) Water Heaters: These are super space-efficient, heating water only as you need it. They can be propane or electric. The downside? Electric models require a massive power draw, often needing a 30-amp breaker or more, which can be a challenge for solar-powered systems.
- Small Tank Heaters: Think 6-gallon electric RV-style tanks. They use less power in short bursts but can run out of hot water. A 6-gallon tank gives you one decent shower. Maybe.
The choice often boils down to your power source. If you have a robust solar setup or are often on grid, an electric tankless is fantastic. For truly off-grid reliability, a propane tankless is hard to beat.
The Drain Game: Gray Water vs. Black Water
This is the part nobody loves to talk about, but it’s arguably the most important. You have two types of waste water, and handling them wrong is… bad.
Gray Water: The “Clean” Dirty Water
Gray water is the runoff from your sink, shower, and washing machine. It contains soap, food particles, and grease, but not human waste. In many places, you can drain gray water directly into a dry well, a mulch basin, or even use it for irrigation (with plant-friendly soaps!).
You’ll need a gray water holding tank if you’re mobile or if local codes require it. It’s generally easier to manage than black water, but it still needs a responsible disposal plan.
Black Water: The Main Event
Black water is what comes from your toilet. This is where your toilet choice is critical. Here’s a quick breakdown of the main options for off-grid tiny houses:
| Toilet Type | How It Works | Pros & Cons |
| Composting Toilet | Separates liquid & solid waste. Solids compost with peat moss; liquids are diverted to a separate container. | Pro: No plumbing needed, no black water tank. Con: Requires maintenance, emptying, and getting used to. |
| Incinerating Toilet | Burns waste into a small amount of ash using electric or gas heat. | Pro: Extremely minimal waste product. Con: Very high energy consumption. |
| Cassette Toilet | Like an RV toilet, with a small, removable waste-holding tank. | Pro: Familiar, easy to find dump stations. Con: You have to manually remove and empty the cassette. |
Composting toilets are the darling of the tiny house world for a reason—they eliminate the need for a complex black water plumbing system and holding tank. That said, they aren’t for everyone. You have to be okay with the process.
Insulation and Winterization: Don’t Let Your Pipes Freeze
If you plan to live in a climate with cold winters, this isn’t a suggestion—it’s a mandate. A single frozen pipe can burst and cause catastrophic damage. You need to build a “heated belly.” This means insulating the underside of your subfloor and all exposed pipes, then installing a heating cable or a small, thermostatically-controlled space heater in the underbelly to keep everything above freezing.
For truly brutal climates, some people use a “skirt” around their tiny house to block wind from whipping under the structure. And if you’re leaving your house unattended in winter, you must winterize the plumbing by blowing out the lines with air and adding antifreeze to the drains, just like with an RV.
A Final Thought: The Philosophy of Tiny House Water Use
Beyond the tanks, pumps, and pipes, the most powerful plumbing “hack” for tiny house living is a shift in mindset. Every drop of water you use, you have to source. Every drop you drain, you have to dispose of. This connection to your resources is profound.
You start taking navy showers. You turn off the tap while brushing your teeth. You see the water from rinsing a vegetable not as waste, but as potential hydration for a plant. Your plumbing system, in all its complicated glory, becomes a direct, tangible link to the environment and your own consumption. And honestly, that awareness might just be the greatest luxury of all.
