Complete Guide to Tiny House Plumbing: Systems, Installation & Cost Analysis

Are you building a tiny house and feeling overwhelmed about the plumbing system? You’re not alone. When I first started planning my tiny house, plumbing seemed like the most intimidating part of the build. But after researching and implementing a functional system, I discovered it doesn’t have to be complicated.

This comprehensive guide will walk you through everything you need to know about tiny house plumbing – from understanding the fundamentals to estimating costs and implementing space-saving solutions.

Understanding Tiny House Plumbing Fundamentals

Tiny house plumbing systems differ from traditional home plumbing in three key ways:

1. Space Constraints: Everything must be compact and efficiently designed
2. Mobility Considerations: If your tiny house is on wheels, the plumbing must withstand movement
3. Water Source Flexibility: Systems often need to accommodate both hookups and self-contained options

Basic Components Every System Needs

Regardless of your specific setup, all tiny house plumbing systems include:

• Water Source: Either hookups or onboard tanks
• Supply Lines: Typically PEX tubing for hot and cold water
• Fixtures: Space-saving sinks, showers, and possibly toilets
• Drainage System: For greywater and potentially blackwater
• Venting: To ensure proper drainage and prevent odors
• Hot Water System: Usually tankless to save space

Planning Your Tiny House Plumbing System

The most crucial step in tiny house plumbing is careful planning. A well-designed system will:

• Minimize pipe runs to save materials and reduce potential failure points
• Group water fixtures (shower, sink) close together when possible
• Create accessible points for maintenance and repairs
• Incorporate proper slopes for drainage

Water Source Considerations

You have several options for water supply:

Space-Saving Design Strategies

Maximize your tiny house’s limited space with these plumbing design strategies:

• Install the shower and kitchen sink on opposite sides of the same wall to share plumbing
• Use wall-mounted fixtures to free up floor space
• Consider convertible or multi-purpose fixtures
• Utilize flexible tubing instead of rigid pipes to navigate tight spaces

PEX Plumbing: The Tiny House Builder’s Best Friend

PEX (cross-linked polyethylene) tubing has revolutionized tiny house plumbing for several reasons:

• Flexibility: Bends around corners without numerous fittings
• Durability: Resistant to freezing and bursting
• Easy Installation: No soldering or specialized tools required
• Color-Coding: Available in red for hot and blue for cold lines

Working with PEX: Tips and Techniques

When using PEX in your tiny house:

• Use “push-to-connect” fittings (like SharkBite) for easy installation
• Follow proper bending radius guidelines to prevent kinks
• Secure PEX lines with proper supports every 32 inches
• Use a proper cutting tool to ensure clean cuts

Water Supply Options for Tiny Homes

City Water Hookups. For stationary tiny houses or those in RV parks:

1. RV Water Inlet Method:
   • Uses a drink-safe hose connected to a spigot
   • Connects to an RV water inlet mounted on your tiny house
   • Quick to connect/disconnect, ideal for mobile tiny houses
   • More susceptible to freezing in cold climates
2. Direct Connection Method:
   • Uses buried PEX line that connects directly to your house
   • Less prone to freezing, neater appearance
   • More permanent solution, not ideal for frequent moves
   • Requires trenching and more technical skill

Onboard Water Systems. For off-grid living or traveling:

Water Tank Considerations

• Average Americans use 100 gallons per day, but tiny house dwellers typically reduce to 10-15 gallons
• Consider weight distribution (water weighs 8.3 lbs per gallon)
• Place tanks over axles when possible for proper weight distribution
• Account for water movement/sloshing when traveling

Pump Options

1. 12-Volt Electric Pump System:
   • Provides pressurized water similar to conventional homes
   • Requires battery power and proper electrical setup
   • More complex but offers convenience
2. Manual Foot Pump System:
   • Simple, reliable operation with no electricity needed
   • More affordable and easier to install
   • Limited to cold water in most setups
   • More conscious water usage due to manual pumping

Drainage, Venting, and Waste Disposal Solutions

Tiny houses produce two types of wastewater:

Greywater (from sinks, showers):

• Can be reused for irrigation in some locations
• Simpler to manage with fewer regulations
• Options include leach fields or collection for disposal

Blackwater (from toilets):

• Requires proper disposal through sewer connections or holding tanks
• Subject to strict regulations in most areas
• Can be eliminated by using composting toilets

Proper Venting Solutions

Venting is crucial for proper drainage and preventing sewer gas backflow:

• Traditional roof vents require penetrating the roof
• Air admittance valves (AAVs) offer space-saving alternatives
• All drain lines need proper venting to function correctly

Toilet Options for Tiny Houses

Step-by-Step Installation Guide

Essential Tools:

• PEX pipe cutter
• PEX deburring tool
• Wrench set
• Level
• Hole saw kit
• Pipe/tubing bender
• Pipe support clamps

Basic Materials:

• PEX tubing (red and blue)
• Push-to-connect fittings
• PVC pipes and fittings for drains
• P-traps for sinks and shower
• Pipe insulation
• Pipe supports and hangers
• Plumber’s tape
• Ball valves for shutoffs

Basic Installation Steps

1. Plan and Mark Locations:
   • Mark all fixture locations and plan pipe routes
   • Identify where pipes will pass through walls, floors
2. Install Water Supply Lines:
   • Mount water inlet
   • Run PEX from inlet to fixtures
   • Install shutoff valves at key points
   • Connect to fixtures with appropriate fittings
3. Install Drain Lines:
   • Ensure proper slope (¼ inch per foot)
   • Install P-traps for each fixture
   • Connect to main drain line
   • Add proper venting
4. Test the System:
   • Pressure test supply lines
   • Check for leaks at all connections
   • Test drainage to ensure proper flow

Safety Precautions

• Always turn off water supply before working on plumbing
• Use protective gear (gloves, eye protection)
• Follow local codes and regulations
• Consider consulting a professional for complex connections

Climate Considerations for Your Plumbing

Cold Weather Protection

Freezing pipes are a major concern for tiny houses, especially those on wheels:

• Insulate all water lines, particularly those in exterior walls
• Use heat tape on exposed pipes and connections
• Keep water moving in extremely cold weather
• Install drain valves at low points for winterization
• Consider heated water hose for external connections

Hot Weather Considerations

Hot climates present different challenges:

• Protect PVC pipes from direct sunlight to prevent degradation
• Insulate hot water lines to maintain temperature
• Consider water heating needs in summer months
• Bury exterior water lines deeper where soil is cooler

Cost Analysis: DIY vs. Professional Installation

DIY Plumbing Costs

Based on real tiny house builds, here’s a breakdown of typical DIY plumbing costs:

Professional Installation Costs

If hiring a plumber:

• Labor costs typically range from $100-$200 per hour
• Most tiny house plumbing installations take 5-10 hours
• Total professional installation: $500-$2,000 (labor only)
• Total with materials: $1,300-$3,580

Additional Cost Considerations

Don’t forget these potential additional expenses:

• Permits and inspections if required
• Septic or sewer connection fees (can be $5,000-$12,000)
• Water tanks if going off-grid ($200-$500)
• Water pumps for off-grid systems ($100-$300)
• Specialized fixtures for tiny spaces (can cost more than standard options)

Essential Tips and Best Practices

Layout Planning Tips

• Position your shower and kitchen sink as close together as possible, ideally on opposite sides of the same wall
• Keep water heaters close to fixtures to minimize waiting for hot water
• Plan for winterization access points and system draining
• Include access panels for all critical connections

Maintenance Best Practices

• Perform regular inspections for leaks and corrosion
• Flush water heaters annually to remove sediment
• Clean aerators and showerheads to prevent mineral buildup
• Winterize properly if leaving the tiny house in freezing temperatures
• Keep a small toolkit for emergency repairs

Common Mistakes to Avoid

1. Not leveling your tiny house: Proper drainage requires proper leveling
2. Forgetting access points: Always provide ways to access plumbing for repairs
3. Improper drain slopes: Too flat won’t drain, too steep can cause problems
4. Skipping shut-off valves: These are crucial for maintenance and emergencies
5. Inadequate insulation: Particularly important for mobile tiny houses in variable climates

Troubleshooting Common Issues

Low Water Pressure

Possible Causes:

• Clogged aerators or showerheads
• Kinked PEX tubing
• Partially closed valves
• Inadequate supply pressure

Solutions:

• Clean fixture aerators and showerheads
• Check for and straighten any kinked lines
• Ensure all valves are fully open
• Consider a pressure booster pump if necessary

Drainage Problems

Possible Causes:

• Inadequate slope in drain lines
• Clogged P-traps
• Improper venting
• Tiny house not level

Solutions:

• Verify proper slope (¼ inch per foot)
• Clean P-traps and drain lines
• Check venting system functionality
• Level the tiny house

Freezing Pipes

Possible Causes:

• Inadequate insulation
• Exposed water lines
• Extremely cold temperatures
• Lack of water movement

Solutions:

• Add insulation to all water lines
• Install heat tape on vulnerable sections
• Keep minimal water flow during extreme cold
• Drain system if leaving house unheated

Conclusion

Tiny house plumbing doesn’t have to be intimidating. With proper planning, quality materials, and attention to detail, you can create a system that’s reliable, efficient, and perfectly suited to your tiny lifestyle.

Whether you’re building from scratch or renovating, remember that simplicity is key. Focus on creating a system that meets your needs without unnecessary complexity, and don’t hesitate to consult professionals for the most challenging aspects of the installation.

Ready to tackle your tiny house plumbing project? Start with a detailed plan, gather your materials, and approach the project one step at a time. Your perfectly functioning tiny house plumbing system is within reach!