RV Toilet Replacement: Step-by-Step Guide & Top Picks NZ

Swapping out a tired caravan loo doesn’t need to be a saga. This guide walks you through every step, from loosening the first bolt to pressing the maiden flush on a brand-new throne — all with tools most travellers already carry. You’ll see how a straight bolt-in replacement can take less than an hour, sparing you a workshop booking and a hefty labour invoice. Best of all, every hint is written for New Zealand conditions and rulebooks.

We’ll compare cassette, gravity-flush and portable options, spotlighting Kiwi favourites such as Thetford and Dometic, and explain the subtle mounting quirks that can catch first-timers. A printable checklist, NZ self-containment pointers, and an honest rundown of top toilets stocked locally at Action Outdoors will be waiting further on. By the end you’ll know exactly which parts to order, where to place each seal, and how to leave the bathroom smelling like—well—nothing at all.

Step 1: Decide if Replacement Is the Right Move

Before you reach for the spanner, pause and confirm that a full RV toilet replacement is actually the smartest fix. Some issues can be solved with a $40 seal, others point to deeper damage that will keep siphoning time and chemicals until you swap the unit out. Spending five minutes on this decision often saves hours later on the road.

A quick inspection with the bowl empty and the pump off will usually reveal which camp you’re in.

Common Faults That Signal It’s Time to Replace

• Cracked ceramic or plastic around the bowl or base – hairline fractures quickly turn into leaks under road vibration.
• Persistent weeping at the floor flange even after a new seal is fitted.
• Flush pedal or electric solenoid that sticks, leaving water (or worse) trickling.
• Musty odours that return within days of a deep clean; deteriorated blade seals let vapour straight into the cabin.

Any of the above affects hygiene and can breach self-containment rules, so replacing the whole unit is usually safer than chasing parts.

Repair vs Replace: Cost & Effort Comparison in NZ

Typical parts prices: blade seal $35–$60, flush valve kit $70–$120. Add an hour of workshop labour at $95–$140 and you’re already nudging half the cost of a brand-new Thetford 345 ($280). DIY-ing an entire toilet swap takes similar effort to a valve rebuild yet gives you fresh internals, warranty cover and better water efficiency. In most Kiwi cases, replacement wins on both dollars and downtime.

NZ Compliance & Compatibility Basics

New Zealand Standard NZS 5465 requires a fixed, vented toilet with waste capacity matching fresh water (1 L : 1 L) for certified self-containment. Cassette and gravity-flush models meet this, portables alone do not. Most motorhomes use a two-bolt pattern spaced 228 mm centre-to-centre, but measure your flange and rough-in distance before ordering. Confirm left- or right-hand water inlets too—Thetford swaps are common, yet a quick tape-measure check prevents return hassles.

Step 2: Measure Up and Pick the Perfect Replacement

A shiny new throne is only a win if it actually fits the cubicle and lines up with your plumbing. A quick tape-measure session eliminates 90 % of install headaches and ensures your RV toilet replacement is truly a bolt-in job, not a renovation. Jot the figures down before you even open the catalogue.

How to Take Accurate Measurements

Start with the rough-in: measure from the finished wall to the centre of the floor flange bolts. Common is 228 mm, but older buses can be anything from 200–250 mm. Next note:

• Bowl height to the floor – important for knee comfort.
• Clearance to the shower wall/door swing – check the seat can lift fully.
• Water line entry – left-hand, right-hand or rear feed.
• 12 V cable length if you’re moving to an electric flush.

Keep the numbers handy in the printable cheat sheet below (copy/paste or screenshot).

Types of RV Toilets Available in New Zealand

Kiwi motorhomes use a handful of toilet technologies, each with upsides and niggles:

• Cassette – Fixed bowl with a removable waste tank.
  • Pros: NZS 5465 compliant, easy dump-station emptying.
  • Cons: Limited tank size; needs regular trips to the dump point.
• Gravity-flush – Classic “drop” straight to a black tank.
  • Pros: Residential feel, larger capacity.
  • Cons: Needs a separate black-water tank and vent.
• Macerator – Electric blades liquefy waste, letting you use small-diameter pipe.
  • Pros: Flexible plumbing layouts.
  • Cons: Higher power draw, pricier parts.
• Composting – Separates solids and liquids; no water required.
  • Pros: Off-grid friendly, zero black tank.
  • Cons: Bulky, learning curve for maintenance.
• Portable/Porta-potti – Self-contained unit, no installation.
  • Pros: Cheapest, lightweight, perfect for small vans.
  • Cons: Not “fixed”, so won’t pass self-containment on its own.

Match the tech to your travel style: freedom campers love composting, families on holiday parks often stick with cassette units for simplicity.

Top Replacement Toilet Picks for Kiwi Motorhomes

Below are crowd favourites available through local suppliers (prices current Aug 2025).

• Action Outdoors – Thetford C223-CS Cassette
  • 12 V electric flush, swivel bowl, 8.8 kg, height 545 mm, $1,049–$1,149
  • Ideal for: Self-containment certificates, small bathrooms needing the swivel trick.
• Dometic 320 Gravity-Flush Ceramic (Platinum RV Supplies)
  • Residential-height 470 mm seat, 12.3 kg, wood-grain lid, $749–$799
  • Ideal for: Full-time living, black-tank setups.
• Thetford Porta Potti 565E (Burnsco)
  • Electric pump flush, 21 L waste tank, 4 kg empty, $329–$359
  • Ideal for: Weekenders, boat/RV crossover use.
• Nature’s Head Composting Toilet (via RV World)
  • No water, crank agitator, 12 kg, $1,695–$1,795
  • Ideal for: Off-grid and coastal conservation areas with water limits.
• Fiamma Bi-Pot 34 Portable
  • Manual pump, 15 L waste, 3.9 kg, $189–$199
  • Ideal for: Budget builds, emergency backup.

Match your measurements with the specs above and you’ll know which box to tick when you hit the checkout button.

Step 3: Gather Tools, Parts and Safety Gear

Before the old bowl comes out, stage your workstation like a pit crew. Having every spanner, seal and sanitiser within arm’s reach cuts the swap time in half and keeps smelly surprises to a minimum.

Essential Tools You’ll Need

A basic RV toolkit already covers most jobs; just add a couple of plumbing extras.

• Adjustable spanner or 13 mm ring spanner for floor nuts
• ¼-inch socket set with short extension
• Phillips and flat-blade screwdrivers
• Putty knife or plastic scraper for old seal removal
• Long-nose pliers for hose clamps and stubborn clips
• Silicone grease and PTFE tape for watertight threads
• Cordless drill with nylon brush (optional for deep-cleaning flange)

Replacement Parts & Seals Checklist

Tick these off before you unbolt anything—couriers can’t save you mid-job.

• Fresh floor-flange seal or wax-free ring matched to your model
• Braided stainless hose or ½" BSP adaptor if inlet thread differs
• 12 V crimp connectors plus heat-shrink (electric flush units)
• Inline mesh filter for the flush line
• Nitrile gloves, absorbent rags and heavy-duty rubbish bags

Safety and Hygiene Prep

Suit up with gloves and safety glasses, crack a roof vent and pre-mix a spray bottle of biodegradable disinfectant approved for NZ freedom-camping zones. A clean tarp on the floor protects vinyl from dropped tools and rogue drips. Take five minutes now—smell the difference later.

Step 4: Shut Off Water & Disconnect the Old Toilet

Time to get your hands wet – but only figuratively. Isolating water and power is non-negotiable for a tidy, shock-free RV toilet replacement. Five minutes of prep will prevent pressurised sprays and blown fuses once the spanner starts spinning.

Turning Off RV Water Supply and Power

1. Flick the water-pump switch to OFF.
2. Close the main isolation tap, usually beside the pump or under the galley sink.
3. For electric-flush or macerator units, pull the relevant 12 V fuse or flip the breaker to kill power at the source. Confirm the flush button is dead before you move on.

Draining and Depressurising the System

• Open any cold tap for a few seconds to bleed residual pressure.
• Flush the toilet once to empty the bowl and line; if you hear a hiss, keep the tap open until it stops.
• Pop the cassette out (if fitted) and cap it—no one likes a slosh surprise.

Removing Bolts, Seal and Lifting Out Unit Safely

• Use a 13 mm socket to loosen the two floor nuts; stash nuts and washers in a tray.
• Gently rock the toilet side-to-side to break the old seal.
• Tilt the unit forward, disconnect the water hose, then lift straight up and out.
• Bag any drips with rags and slide the old toilet onto your tarp for disposal or parts scavenging.

Step 5: Inspect, Clean & Prep the Floor Flange

With the old loo out of the way, the floor flange becomes centre-stage. A spotless, undamaged flange is your best defence against future leaks and smells, so give it a proper once-over before the new throne lands.

Assessing Flange Condition

Shine a torch down the pipe and inspect the plastic collar. Hairline cracks, warped edges or stripped brass inserts mean it won’t hold tension. Lightly tug each mounting stud; if it wiggles, the flange is toast. Replacement kits run $35–$60—cheaper than chasing weeps on the road.

Cleaning Technique & Waste Disposal Rules in NZ

Scrape off every scrap of wax or rubber with a plastic putty knife—metal can gouge ABS. Follow with paper towels soaked in eco-safe disinfectant, then a nylon-brush drill attachment if buildup persists. Bag residue in a double-lined rubbish sack. Under NZ freedom-camping bylaws, dump only at authorised stations or council wastewater drop-off points.

Installing or Replacing the Wax/Rubber Seal

Most modern RVs use a polyurethane ‘closet’ ring that compresses without mess; wax is still fine on gravity systems in warmer climates. Seat the new ring squarely over the flange lip, shiny side up, and smear a fingertip of silicone grease. Avoid stacking seals—extra height often equals leaks.

Step 6: Fit and Secure the New Toilet

The flange is spotless, the seal is seated, and you’re finally ready for the fun part—dropping the new throne into place. Slow and steady wins here; a crooked landing can pinch the seal or snap a mounting stud, turning an easy RV toilet replacement into a leak hunt. Keep a mate nearby if the unit is heavy or if the bathroom space is tight.

Lowering the Toilet onto the Flange

1. Dry-fit first: hover the bowl over the studs and check clearances.
2. Mark the bolt centres with a strip of painter’s tape on the floor—handy alignment guide.
3. Lift, centre the bowl over the seal, and lower vertically in one smooth motion. A gentle wiggle helps the seal compress evenly.

Tightening Bolts Without Cracking

• Hand-thread nuts until finger-snug.
• Alternate sides, adding a quarter-turn at a time with a socket or spanner.
• Stop when you feel firm resistance; overtightening can spider-crack plastic bases or distort ceramic. If the bowl still rocks, add nylon washers rather than cranking harder.

Connecting Water Line and 12 V Power (if applicable)

• Wrap male threads with two turns of PTFE tape; avoid paste sealants.
• Attach the braided hose, tightening just past hand-firm—no need to reef on it.
• Re-install the inline filter, then reconnect 12 V leads: red to positive, black to negative. Crimp and heat-shrink for vibration-proof joints.
• Tidy excess cable and hose with soft clamps to prevent chafe on corrugated Kiwi roads.

Step 7: Test, Troubleshoot and Maintain

The new throne is bolted down, but the job isn’t finished until you’ve proved every joint is drip-free and the flush behaves. A quick systematic test now prevents messy surprises on the first road leg.

Initial Leak & Flush Test

1. Re-open the isolation tap and flick the pump back on.
2. Let the system pressurise, then flush three full bowls while watching the hose, base and cassette hatch.
3. Dry-wipe around each joint; any damp patch is easier to spot on tissue than on shiny plastic.
4. Confirm the bowl refills to the correct level and the seal shuts cleanly—no lingering trickle should be heard.

Troubleshooting Common Issues After Install

• Slow or weak flush: check that the hose isn’t kinked and the inline filter isn’t reversed.
• Continuous water flow: pedal return spring misaligned or electric solenoid wired backward; re-seat and retest.
• Persisting odour: verify the vent pipe isn’t blocked by insect screen debris; top up with enzyme additive if the tank is empty.
• Bowl rocks when sat on: back off nuts, slip in a nylon shim, then re-torque hand-tight plus ¼ turn.

Ongoing Maintenance Tips for Odour-Free Use

• Monthly: drop a cap of Thetford seal conditioner (or a dab of olive oil) onto the blade and cycle it twice.
• After each dump-station visit: rinse the waste tank with 2–3 L of grey water and a dash of eco-friendly treatment.
• Quarterly: inspect mounting nuts and re-tighten if road vibration has loosened them.
• Winter lay-up: drain bowls, blow out the flush line, and add a cup of non-toxic RV antifreeze to prevent valve damage.

Follow these simple checks and your RV toilet replacement will stay sweet-smelling and worry-free for seasons to come.

Enjoy the Upgrade

Measure twice, order once, then follow the seven steps and you’ll swap stress for comfort in under an hour. A toilet that fits, passes NZS 5465, and actually smells like nothing is a small luxury that pays off every trip. When you’re ready for seals, hoses or that shiny Thetford kit, jump over to Action Outdoors and get it on the courier for tomorrow’s install.