Plumbing Systems for 6x12 Trailer Conversions
A 6x12 trailer has limited space, but that doesn't mean you have to skip running water. Here's how to set up plumbing that works in a compact footprint.
A 6x12 cargo trailer plumbing system typically includes a 10-20 gallon freshwater tank, a compact sink, and a 5-15 gallon greywater tank, costing $360-$920 in DIY materials. Most builds use a hand pump or 12V electric pump for water pressure, and skip hot water in favor of stove-heated water. Emery Custom Builds designs 6x12 plumbing systems that match your actual camping style -- from basic hand-pump setups to full pressurized systems with hot water.
What Plumbing Can You Fit in a 6x12 Cargo Trailer?
A 6x12 gives you about 72 square feet of total floor space. Every gallon of water weighs 8.3 pounds, and every tank takes up room you could use for sleeping or storage. The goal is a plumbing setup that covers your actual needs without eating half the trailer.
Most 6x12 builds stick to a single sink with cold water, a small freshwater tank, and a basic greywater collection system. That covers cooking, hand washing, and cleanup. Anything beyond that (hot water, shower, toilet) is possible but requires trade-offs.
Typical 6x12 Plumbing Setup
Freshwater Tank
10–20 gallons. Mounted under the trailer or inside a cabinet. A 15-gallon tank is the sweet spot for most weekend builds—enough water for 2–3 days without adding too much weight.
Water Pump
Hand pump (zero power draw, totally reliable) or a 12V electric pump like a Shurflo (pressurized water at the faucet, draws 3–5 amps).
Sink & Faucet
A compact bar sink or RV-style sink with a single faucet. Stainless steel is durable and easy to clean. Some builds use a fold-down sink to save counter space.
Greywater Collection
A 5–15 gallon greywater tank underneath the trailer, or a simple bucket-and-drain setup for dry camping. Gravity-fed from the sink drain.
Toilet (Optional)
Portable cassette toilet or composting toilet. No plumbing required—just a dedicated space with ventilation.
How Big Should Your Freshwater Tank Be?
How big does your tank need to be? It depends on how you use water:
- • Cooking and hand washing only: 10 gallons lasts 3–4 days for one person. Minimal weight (83 lbs full).
- • Cooking, washing, and light cleanup: 15 gallons is the most common choice. Lasts 2–3 days for two people. Weighs about 125 lbs full.
- • Extended trips or outdoor shower: 20 gallons. Heavier (166 lbs) but gives you more flexibility before needing a refill.
Tank placement matters. Under-trailer mounting keeps floor space free but exposes the tank to road debris and freezing temps. Inside mounting (under a bench or in a cabinet) protects the tank but takes up living space.
Should You Use a Hand Pump or Electric Water Pump?
This is one of the first decisions in a small trailer plumbing build:
Hand Pump
$20–$60
Uses zero electricity. Simple to install—just a foot pump or hand lever at the sink. Nothing to break, nothing to wire. The trade-off is convenience: you're pumping manually every time you need water. Works well for minimalist camping builds.
12V Electric Pump (Shurflo or Similar)
$60–$150
Pressurizes your water line so water flows when you turn the faucet handle—just like at home. Draws 3–5 amps from your 12V system. Requires wiring and a pressure switch. Standard on any build with an electrical system already in place.
If your trailer has a solar and battery setup, go electric. If you're building a bare-bones rig with no electrical, a hand pump keeps things simple and reliable.
How Do You Handle Greywater in a 6x12 Trailer?
Every drop of water you use has to go somewhere. In a trailer, you have two options:
- • Greywater tank (5–15 gallons): Mounted under the trailer. Sink water drains into it by gravity. You dump it at RV dump stations. This is the standard approach for any build that will visit campgrounds or RV parks.
- • Bucket drain: A hose from the sink drains into a portable bucket or jug. Simpler, cheaper, no tank mounting needed. Works for dry camping and boondocking where you manage water carefully.
Either way, never dump greywater on the ground. Most campgrounds and many public parks have dump stations. Plan your stops around them if you're on the road for more than a weekend.
Do You Need a Water Heater in a 6x12 Trailer?
Most basic 6x12 builds skip hot water entirely. Here's why—and when it makes sense to add it:
- • Skip it (most common): Heat water on the stove for dishes. Use campground showers or a solar shower bag for bathing. Saves $500–$1,500 and a lot of space.
- • Tankless propane heater: Compact units (like Camplux or Eccotemp) mount on the wall and heat water on demand. Needs propane and venting. Adds $200–$500 for the unit plus installation.
- • Small electric water heater: Uses significant battery power. Only practical if you have a large electrical system (400W+ solar, 300Ah+ battery). Not typical for a 6x12.
What Toilet Works Best in a Small Cargo Trailer?
A toilet is optional in a 6x12, but if you want one, here are your choices:
Portable Cassette Toilet
$80–$200
Self-contained, no plumbing needed. A freshwater flush tank on top, a waste cassette on the bottom. Pull out the cassette to dump at any RV dump station. Thetford and Dometic make the most popular models. Takes up about 1.5 sq ft of floor space.
Composting Toilet
$800–$1,500
Separates liquids and solids. No water, no chemicals, no black tank. Requires a small vent fan (12V, minimal draw). Nature's Head and Airhead are the go-to brands. More expensive upfront but zero dumping hassle long-term.
No Toilet
$0
Many 6x12 owners skip the toilet entirely and use campground facilities. Frees up space for other things. If you only camp at developed sites, this is a practical choice.
How Much Does a Complete 6x12 Plumbing System Cost?
Professional installation adds $800–$1,500 in labor depending on complexity. A full plumbing system with hot water and composting toilet can push the total to $2,500–$4,000 installed.
How Do You Get Started with Your Plumbing System?
Plumbing in a small trailer is about matching the system to how you actually camp. A consultation helps us figure out whether you need a simple hand pump and bucket or a full pressurized system with hot water. We'll design around your space and budget.
Related guides: 6x12 Conversions · Plumbing Systems · 6x12 Electrical · 6x12 Cost Breakdown · 6x12 Interior
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