Guide to RV Water Tanks in New Zealand: Fresh, Grey & Self-Containment

Why Water Tanks Matter in a Campervan

Water tanks are the unsung heroes of vanlife. Whether you’re chasing self-containment certification, planning a remote South Island adventure, or just trying to avoid another campground sink, having a well-planned water system is crucial.

This guide is for DIY vanbuilders, rental fleet owners, and weekend warriors who want to understand RV water tanks from top to bottom. We cover everything from tank types and materials to installation, maintenance, and Green Warrant compliance.

Types of RV Water Tanks

RV Fresh Water Tanks (For Drinking, Cooking & Washing)

Your fresh water tank is one of the most important components in your campervan setup. It supplies all the clean water you use for:

• Drinking

• Cooking

• Brushing teeth

• Showering

• Dishwashing

To ensure safety and functionality, it must be properly sealed, made from food-grade materials, and securely installed in your vehicle.

Food-Grade Materials Only

Your fresh water tank should be made from food-safe polyethylene or certified stainless steel. This ensures it is safe for long-term storage and won’t leach chemicals into your water, but also that it complies with New Zealand self-containment standards.

💡 Tip: Look for terms like BPA-free, NSF/ANSI 61 certified, or AS/NZS 4020 compliant when purchasing.

Sealing and Access

Fresh tanks must be:

• Fully sealed to prevent contamination

• Fitted with a screw-top or filler cap

• Properly vented to allow air in as water is used

• Equipped with an accessible inspection lid (optional but highly recommended for cleaning)

Even small gaps in tank lids or poor plumbing seals can introduce bacteria or dirt into your supply.

Placement and Mounting

Fresh water tanks can be internally mounted (under seats or beds), which is best for protection, access, and year-round use, or externally mounted (underfloor), which saves space but may require insulation and shielding.

Always ensure your tank is:

• Mounted level or angled toward the outlet for full drainage

• Strapped securely to avoid shifting while driving

• Accessible for cleaning and repairs

Externally mounted water tank - installed by Vanlifer on a LDV Deliver 9 Campervan

Keeping Your Water Clean

To maintain a safe water supply:

• Sanitize the tank every 2–3 months, or before extended trips

• Use clean hoses when filling

• Avoid topping off at suspect sources (e.g. garden hoses or public taps without backflow protection)

• Install an inline carbon filter to improve taste and remove chlorine

See our sanitising instructions for more tips on how to sterilise your RV fresh water tank.  

RV Grey Water Tanks (Wastewater from Sinks and Showers)

Grey water tanks collect used water from your campervan’s sink, shower, and sometimes a hand basin if installed. Unlike black tanks, grey water does not contain sewage — but it still poses environmental risks and must be handled properly.

What Goes Into a Grey Tank?

• Dishwater from your kitchen sink

• Toothbrushing and handwashing water

• Shower runoff

Grey water often contains soap, grease, and food residue, making it unsafe to discharge directly onto the ground.

Venting Is Essential

Grey tanks must be vented to the outside to allow air in as water fills the tank and to prevent pressure buildup. This also prevents unpleasant smells from backing up through your plumbing into the van.

Here are the most common venting methods:

• A dedicated breather hose run up and out of the van

• A high-mounted air admittance valve (AAV) in enclosed plumbing

• A through-roof or side-wall vent for underfloor tanks

Improperly vented grey tanks can lead to:

• Gurgling or slow drainage

• Bad smells in the van

• Reduced capacity from airlock pressure

Drainage & Legal Dumping Requirements in New Zealand

To comply with the Green Warrant and NZS 5465:2001:

• Your grey tank must have a minimum capacity matching your fresh tank

• The tank outlet must be at least 20mm in diameter

• It must include a secure cap or shut-off valve

• Dumping must only occur at authorised dump stations

Even for portable grey tanks, these requirements still apply.

Find dump stations near you

Design Tips for Self-Containment Water Tanks

Install your tank close to the sink outlet to avoid long hose runs. Use gravity-fed drains if possible. Include an easy-access drain valve underneath or at the rear of the van.

For optimal preservation, rinse regularly your fresh water tank with hot water and vinegar. Never let grey tanks sit full for long periods.

💡 For easy, compliant, and risk-free water system installation in NZ, opt for the Vanlifer Self Containment Plumbing Kit.

RV Black Water Tanks (Toilet Waste Tanks)

Black water tanks store waste from flush toilets. They are separate from grey tanks, which only hold water from sinks and showers.

In most campervans, black tanks are uncommon. Instead, travellers opt for portable cassette toilets (like Thetford or Dometic models) or composting toilets, which are easier to manage and don’t require a full sewage handling system.

However, black tanks are more commonly used in:

• Larger motorhomes with full bathrooms

• Buses and RVs with fixed flush toilets

• Boats and marine vessels, where plumbing is centralised

What You Need To Know

RV black water tanks require specialised plumbing and venting, as well as chemical additives or fans to manage odour. It must be emptied at black water-compatible dump stations.

Please note that a black water tank adds extra weight and takes up more space than most small vans can spare. It is not required for NZ self-containment – a portable toilet is acceptable.

For most van builds, portable, fixed cassette or composting toilets are lighter, easier to install, and more practical.

Easy system for emptying fixed BlackMoa toilet - installed by Vanlifer in a Nissan Serena

Green Warrant Water Tanks: Portable vs Fixed

Portable tanks are removable containers. Fixed tanks are mounted and plumbed into your van. Both can be self-containment compliant if installed correctly.

Why Opt For a Portable Tank?

There are two types of portable water tanks:

• Portable tank (10–25L)

• Roll tanks (up to 40L)

Portable water tanks are recommended for small campers and weekend builds. It’s the best alternative for those looking for a cost effective option as well as an easy refill and dump access.

Portable water tanks (jerry cans) - installed by Vanlifer in a Ford Transit

Are Portable Tanks Compliant?

Yes – if they are fixed in place during inspection, properly vented, and plumbed per regulation.

Where to buy:

• Burnsco - Water Container 20L

• Burnsco - Water Container 25L

• Challanger Yachts - Challenger 25L Water Tank with Spout & Level Indicator

• Bunnings - Marquee 25L Water Container With Tap

• Bunnings - Marquee 20L Water Storage Container W/tap

• Bunnings - Marquee 12L Water Container With Tap

• Super Cheap Auto - Pro Quip Water Carry Can 22 Litre Green

• Super Cheap Auto - SCA Water Carry Can 20 Litre Blue

• Super Cheap Auto - SCA Water Carry Can Cube 25 Litre Blue

• Complete Outdoors - Kiwi Camping Jerry Can Water Carrier with Tap - 22L

• The Warehouse - Navigator South Jerry Can with Tap 20L

• Tomaq - 28L Mobile Camping Water Tank - Beige

• RV Mega - 25 litre Jerry Can with Cap

• Mitre 10 - Kiwi Camping Polycarbonate Water Carrier 22L

• Kmart Water Container - 23L

• Vanlifer Self Containment Plumbing Kit 

Custom Campervan Water Tanks: Choosing the Right Size

Getting your tank sizing right is key to both daily usability and Green Warrant compliance. Your setup should reflect how you actually use water on the road — whether that’s brushing teeth at a DOC campsite or taking a quick shower off-grid.

How Much Water Do You Use Per Day?

These estimates are based on typical vanlife use, customer experience, and guidance from motorhome manufacturers:

So in practice:

• Weekend use (no shower): 10–15L per person per day

• Off-grid living (with shower): 20–30L per person per day
  

NZ Self-Containment Minimums

To meet NZS 5465:2001 and receive your Green Warrant, your van must carry:

• 4L of fresh water per person per day, for 3 days
  → That’s 12L per person minimum
  

• A grey tank equal to or larger than the fresh tank
  

 

What If You Have a Shower?

A short motorhome shower uses 18–50L, depending on flow rate and duration.
If your van includes a fixed shower, you should install:

• At least a 50L fresh water tank

• A grey tank of the same or larger capacity
  

Common Real-World Setups

Many small campervans in New Zealand, including ex-rentals and budget builds, use:

• 25L fresh water tank
  

• 25L grey water tank
  

This setup is compliant for 1–2 people and ideal for short trips and city-based travel. However, it is inadequate for long off-grid stays or shower use unless topped up frequently.

Typical RV Water Tank Sizes in NZ

 

Slimline, wheel-arch, and underbody tanks help you fit large volumes even in small vans.

What Are RV Tanks Made Of?

The material your water tank is made from affects everything — weight, durability, taste, hygiene, and even how easy it is to install. Here's a breakdown of the two main materials used in New Zealand campervans:

Polyethylene (Plastic)

Polyethylene, especially the high-density (HDPE) or medium-density (MDPE) variety, is by far the most common material for RV water tanks.

Why it's popular:

• Lightweight — critical for fuel efficiency and payload limits
  

• Non-corrosive and UV-resistant — lasts well in NZ’s outdoor conditions
  

• Easy to shape and install — ideal for under-bed, wheel-arch, or under-chassis placement
  

• Affordable — significantly cheaper than stainless steel alternatives
  

• Readily available — most pre-moulded tanks in NZ are made from poly
  

💡 Tip: Choose tanks that are rotationally moulded in one piece, not welded or glued — they’re stronger and less prone to leaks.

Polyethylene portable water tanks - installed by Vanlifer in a Nissan Serena

Stainless Steel

Stainless steel tanks are durable, inert, and widely used in the marine, food, and industrial sectors — including high-end campervan builds.

Advantages:

• Extremely durable — won't degrade under pressure or UV exposure
  

• Hygienic and easy to clean — smooth surfaces resist bacterial buildup
  

• No plastic taste — great for drinking water
  

• Can be custom fabricated — fits odd spaces perfectly
  

But stainless steel also has some downsides: it is heavier than poly (which affects fuel economy and requires stronger mounting) and more expensive ( costlier to produce and transport). It also conducts heat, which means it may need insulation if exposed to sunlight or freezing temperatures.

In short, stainless tanks are best for long-term, full-time travel, high-end motorhomes, or off-road campers that face constant vibration and impact.

BPA-Free and Food-Safe Considerations

Not all plastic tanks are created equal.

When storing drinking water, make sure the tank is:

• Certified food-grade (AS/NZS 4020 or NSF-61)
  

• BPA-free and free from harmful additives
  

• Opaque or UV-resistant to prevent algae growth
  

• Labeled for potable water use
  

Some cheaper jerry cans or portable tanks are not suitable for long-term drinking water storage — especially if stored in a hot van.

A quality tank might cost more upfront, but it pays off in health, taste, and system lifespan.

NZ Self-Containment Rules: The Green Warrant

To legally freedom camp in New Zealand, your van must be certified self-contained. That includes:

• A fixed fresh and grey water tank (size based on your toilet type and van occupancy)

• Secure outlets and inlets

• Proper venting

• Compliance with NZS 5465:2001

Use our self-containment eligibility checker

Should You Get a Custom Water Tank Made?

Why Choose a Custom Made RV Water Tank?

It is recommended to opt for a custom water tank if you plan to mount it between chassis rails or to fit it around furniture and framing. A custom made tank will allow you to maximise odd shapes or under-bed cavities.

When choosing the best material, you can either go for plastic (lighter, cheaper and easier to install) or stainless steel (more durable and easier to clean).

As for the mounting, it can be internal (best protected from road damage) or external (saves space but requires insulation and strong brackets).

Custom RV Water Tank Manufacturers in NZ

• KiwiTanks (Auckland)

• Plastic Welding Repairs (Christchurch)

• Advantage Plastics (Hamilton)

• Custom Stainless (Auckland)

• Vanlifer (custom integration)

How to Fill, Drain & Maintain Your Water Tanks

Filling RV Fresh Water Tank

The method to fill your fresh water tank depends on the type of tank: fixed or portable.

Fixed Water Tank: External Filler Cap With Hose

The most convenient and common way to fill your fresh water tank is to use a hose. RVs with built-in fresh water tanks are equipped with an external filler cap, typically located on the side of the RV.

To do so, you’ll need a clean, drinking-water-safe hose (typically white or blue), as well as a water filter and a water pressure regulator (both optional, but recommended).

Then, follow these steps:

1. Locate the fresh water fill port: it is usually labeled as “Fresh Water Fill” and will have a cap that can be unscrewed

2. Attach the hose to a potable water source

3. (Optional) Install a water filter and/or regulator to protect your system and ensure water quality

4. Insert the other end of the hose into the filler port

5. Turn on the water slowly to fill the tank gradually. To know when the tank is full, you can listen for a change in sound, check a tank monitor inside the RV, or wait for water to spill back from the fill port.

6. Remove the hose and replace the cap.

Important: Never use the same hose for black tank flushing or any non-potable water use to avoid contamination.

Portable Fresh Water Tank: Manual Refill

If your van is equipped with a portable water tank, you’ll have to manually fill it using clean portable water containers and a funnel or transfer pump.

Follow these steps:

1. Take a container to a potable water source

2. Fill it fully using a clean hose

3. Bring the filled container back to the RV

4. Pour the water into the fresh water tank manually. This can be done through a top cap or funnel, depending on your setup.

5. Secure the cap to prevent contamination.

Tip: This method is also great for boondocking or dry camping when you're far from a water hookup and need to refill using water from another location.

Draining Grey Tank

Draining your grey tank properly is essential for hygiene, odor control and environmental responsibility.

As it contains soap, food particles, grease, and bacteria, dumping it onto the ground is illegal in many places and can harm the environment. You must use authorized dump stations only. These are commonly found at campgrounds, rest stops, RV parks or truck stops.

To safely drain your grey water tank, make sure your sewer hose is tightly connected to both the RV and the dump station inlet. Always wear gloves for hygiene. Fully open the grey tank valve to allow a strong, steady flow of water and avoid leaving residue in the tank or hose. After draining, flush the hose with clean water to prevent buildup or odor.

💡 Pro tip: Dump your black tank first, then your grey tank. The grey water helps rinse the sewer hose clean.

Find dump stations near you

Here are the best practices to prevent grey water smells:

• Keep tank clean

• Use venting correctly

• Avoid food waste in sink

Sanitising

Keeping your RV’s fresh water tank and plumbing system clean is essential for safe drinking water, avoiding odors and preventing bacterial growth. Even if the water looks clean, bacteria and mold can build up inside the tank, hoses or faucets over time — especially if the RV has been sitting unused.

How Often Should You Sanitize?

• Every 2–3 months during regular use

• Before your first trip of the season (especially after winter storage)

• After purchasing a used RV

• If the water smells, tastes off, or appears cloudy

• After filling from an unfamiliar or questionable water source

How to Sanitize Your Fresh Water Tank

The most common and effective method is to use a diluted bleach solution (1/4 cup of bleach for every 15 gallons of fresh water tank capacity).

First step is to drain the fresh water tank completely using the drain valve. Then, dilute the bleach in at least 1 gallon of water before adding it to the tank by pouring it or using a funnel. Fill the fresh water tank with clean potable water until full and run each faucet (hot and cold) until you smell bleach at each outlet — this ensures the solution is in all water lines.

Let it sit for 8 to 12 hours (overnight is best) before draining the system completely. Refill with clean water, then flush each faucet until the bleach smell is gone. You may need to flush 1–2 times to completely remove all traces of bleach.

If you prefer not to use bleach, white vinegar is a gentler, food-safe option, although not as strong for disinfecting.

To do so, use 1 quart of distilled white vinegar for every 15 gallons of tank capacity. Follow the same steps: drain, mix with water, add to the tank, fill, run through faucets, let sit for a few hours, and then flush thoroughly.

Note that vinegar is good for odor control and mineral buildup but may not kill all bacteria or viruses like bleach does.

Vanlifer Recommended Tank Brands & Where to Buy in NZ

 

Pumps, Filters, and Gauges – The Essentials for Your RV Water System

12V Pumps

12-volt pumps are the heart of your RV’s fresh water system, pushing water from the tank to your faucets and shower.

The most common brands are Shurflo, Whale and Flojet. Choose models with pressure shut-off (typically 35–55 PSI) to prevent overpressure and save power.

Check out a selection of water pumps recommended by Vanlifer:

• Dometic 12V Water Pump
  
• Seaflo 42 Series RV Pressure Pump 11.3LPM 55psi
• Seaflo 12V 23A Series Diaphragm Water Pump 40PSI

Water Filters

Filters help keep your water clean, safe, and good-tasting.

There are two main types:

• Sediment filters – remove particles like dirt, sand, and rust

• Carbon filters – reduce chlorine, bad taste, and odors

Inline options exist for both pressurised and gravity-fed systems.

Gauges & Sensors

These help you monitor water levels and avoid overflows. 

• Float switches are simple and reliable sensors for tank levels

• LED readouts display fresh, grey, and black tank levels on a control panel

• Grey tank overflow alarms warn you when the grey water tank is nearly full, preventing backflow or spills.

Self-Containment Water Tank in NZ - FAQs

Can I use a portable tank for self-containment in NZ? Yes, if fixed, vented, and properly connected.

What size water tank do I need for a campervan in NZ? To comply with the Green Warrant, you must carry at least 12L per person for 3 days, i.e., a 25L container for 2 people. If your campervan has a shower, you will need to opt for a fresh water tank of at least 50L. The grey water tank must be the same size or larger than the fresh water tank.

What size tank fits in a Hiace? Usually 40–57L, often under bed or in wheel arch cutout.

What’s the difference between fresh, grey, and black water tanks? Fresh water tanks contains clean drinking water, grey water tanks collect used water from sinks and showers, and black water tanks store toilet waste.

Do I need to vent my tank? Yes, both fresh and grey tanks must be vented.

How do I clean my fresh water tank? Use diluted bleach or white vinegar and rinse thoroughly.

How do I stop my grey water tank from smelling? To stop your grey water tank from smelling, regularly clean it, ensure proper venting and avoid letting food or grease go down the drain.

Can I mount tanks underneath? Yes, with secure brackets, insulation, and drain access.

How long can I keep fresh water in my RV tank? From a couple of days up to a couple of weeks - depending on storage conditions - if you are using it for drinking and cooking.

Dump Stations & Water Refill Points

Use Vanlifer's free map of dump stations and refill points in New Zealand: Dump Station Finder Tool

Vanlifer's Tips for First-Time Builders

• Plan water before cabinetry

• Mount securely and with future access in mind

• Use proper hose sizes and venting

• Label your outlets clearly

• Triple-check Green Warrant plumbing rules

Common Mistakes to Avoid

• Undersizing fresh or grey tanks

• Skipping venting

• Using non-food-grade hoses

• Poorly supported external tanks

• Forgetting access for maintenance

Need Help?

Vanlifer builds smart, lightweight water systems designed for self-containment and real-world travel.

Explore our campervan kits or get in touch for custom advice.

Happy building – and happy hydrating.