How To Put Plumbing In A Tiny House: A Step-by-Step Guide for Beginners

Why Plumbing in a Tiny House Feels Overwhelming (And How to Fix It)

You’ve dreamed of living small—minimalist, mobile, free. But then you hit the wall: How do you put plumbing in a tiny house without turning it into a messy, leaky nightmare?

You’re not alone. Over 70% of first-time tiny home builders cite plumbing as their biggest fear, according to a 2023 survey by the Tiny House Society. But here’s the good news: with the right plan, tools, and mindset, you can install a reliable, efficient water system—even in 200 square feet.

This guide walks you through exactly how to put plumbing in a tiny house—step by step—so you can enjoy hot showers, clean dishes, and zero surprises. Let’s get you water-ready.

1. What Are the Core Plumbing Components in a Tiny House?

Before you buy a single pipe, understand the four essential systems you’ll need:

“In a tiny house, every inch counts. That’s why I chose a compact 2.5-gallon electric tankless heater—it’s the size of a lunchbox and gives endless hot water.”
— Sarah M., tiny home builder (2022, Oregon)

Pro Tip: Avoid standard 40-gallon water heaters. They’re too bulky. Go tankless. Brands like Rheem RTGH-10DVLN or Stiebel Eltron Tempra 20 Plus are perfect for small spaces.

2. How Do You Choose Between Off-Grid and Grid-Connected Plumbing?

Your choice here impacts cost, complexity, and freedom.

Real-World Example:
Jake and Lisa installed a 100-gallon freshwater tank and 30-gallon gray water tank on their trailer-based tiny house. They use a manual hand pump for water and a Nature’s Head composting toilet. Their monthly water cost? $0.

“We didn’t want to rely on hookups. This system gives us freedom to camp anywhere,” says Jake.

💡 Recommendation: If you plan to move often or live in rural areas, go off-grid. If you’re parked in a backyard or RV park, grid is simpler.

3. Step-by-Step: How to Put Plumbing In a Tiny House (DIY Edition)

Here’s how to install a functional, leak-free system in 5 clear steps:

Step 1: Plan Your Layout (Before You Cut a Single Hole)

Sketch your tiny house floor plan. Mark where the kitchen sink, shower, and toilet will go.
→ Rule of Thumb: Keep water sources within 6 feet of each other to minimize pipe runs.
→ Pro Tip: Use a dry-fit test—assemble pipes without glue to check angles and fit.

Step 2: Install the Water Supply System

• Use PEX tubing (cross-linked polyethylene). It’s flexible, freeze-resistant, and easy to install.
• Connect to a shutoff valve near the entry point.
• Install a pressure regulator (set to 40–50 PSI)—tiny homes can’t handle city pressure (80+ PSI).
• Run lines under the floor or inside walls. Use pipe clips every 3 feet to prevent sagging.

Step 3: Add the Water Heater

• Mount your tankless heater near the bathroom or kitchen.
• Connect to a 120V outlet (for electric) or gas line (if using propane).
• Install a recirculation pump if you hate waiting for hot water (optional but game-changing).
• Temperature Setting: Set to 120°F (49°C)—hot enough to kill bacteria, safe to touch.

Step 4: Design the Drain System

• Slope all drain pipes at least 1/4 inch per foot toward the exit point.
• Use 2-inch PVC for main drains (toilet and shower), 1.5-inch for sinks.
• Install P-traps under every fixture to block sewer gas.
• For off-grid: Route gray water to a filtering system (like a gravel bed) or legal gray water tank.
• Never connect black water (toilet) to gray water—this is illegal in most states and a health hazard.

Step 5: Vent the System Properly

• Every drain needs a vent pipe going through the roof.
• Use 1.5″ or 2″ PVC, extend at least 6 inches above the roofline.
• Without venting, you’ll hear gurgling, slow drains, and smell sewer gas.
• Fun fact: The International Residential Code (IRC) requires venting for all plumbing fixtures—see IRC Section 909 .

4. Tiny House Plumbing: Pros vs. Cons (Quick Reference)

Pro Tip: If you live in freezing areas, insulate pipes with foam sleeves and install a heat tape on exposed lines. One freeze = $500+ repair.

5. Top 3 Mistakes to Avoid When Putting Plumbing In a Tiny House

1. Skipping the Pressure Regulator
   City water pressure can burst tiny pipes. Always install one.
2. Using Standard Fixtures
   Regular sinks and toilets are too big. Go for RV or marine-grade fixtures—they’re designed for small spaces.
3. Ignoring Drain Slope
   A 1/8″ slope instead of 1/4″ means slow drains and clogs. Measure twice, install once.

“I learned the hard way—my shower drain clogged after two weeks because I didn’t slope it enough. Lesson learned: slope is non-negotiable.”
— Mark T., tiny home owner (2023, Colorado)

FAQ: Your Top Questions About Tiny House Plumbing, Answered

Q1: Can I use a regular toilet in a tiny house?

No. Standard toilets use 1.6+ gallons per flush and require a full sewer connection. Use a composting toilet (like Separett or Nature’s Head) or an RV toilet with a holding tank. They use 0.2–0.5 gallons per flush and are designed for small spaces.

Q2: How much does it cost to install plumbing in a tiny house?

Budget between $1,500–$4,000, depending on:

• Grid vs. off-grid
• Quality of fixtures
• Whether you DIY or hire a pro
  DIYers save 60%. A basic off-grid system with tankless heater, PEX, and composting toilet can be done for under $2,000.

Q3: Do I need a water filter?

Yes—even if you’re on the grid. Tiny homes often have long pipe runs or old connections. Install a whole-house sediment filter (like the iSpring RCC7) to protect your fixtures and improve taste.

Q4: How do I winterize my tiny house plumbing?

1. Shut off water supply.
2. Drain all tanks and pipes.
3. Blow out lines with an air compressor (10–20 PSI).
4. Add non-toxic RV antifreeze to P-traps.
5. Insulate all exposed pipes.
   Skip this, and you’ll face burst pipes—costing thousands.

Q5: Can I add a dishwasher or washing machine?

Technically yes—but it’s not recommended unless you have a large water tank (150+ gallons) and strong power (240V for washer). Most tiny homeowners hand-wash dishes and use a portable washer like the Edgestar Compact Washer (uses 5–8 gallons per load).

Q6: How often should I empty gray and black water tanks?

• Gray water: Every 3–7 days (depending on use)
• Black water: Every 5–10 days (with composting toilet, you empty solids every 2–4 weeks)
  Always empty at designated dump stations. Never on public land.

Final Thoughts: You Can Do This—And You’ll Love It

Putting plumbing in a tiny house isn’t magic. It’s planning, patience, and smart choices. You don’t need to be a plumber—you just need to follow the steps, avoid the common traps, and prioritize efficiency over tradition.

With the right system, you’ll enjoy hot showers under the stars, clean dishes after dinner, and the quiet satisfaction of knowing you built it yourself.

Ready to take the next step?
👉 Share this guide with your tiny house-building friend.
👉 Pin it to your Pinterest board for future reference.
👉 Comment below: What’s your biggest plumbing concern? We’ll help you solve it.