How to Pick the Best Water Tank for Your Camper Van
A Builder Minded Way to Decide Without Guessing
Choosing a water tank is one of the most important early decisions in a camper van build. It affects layout, plumbing, winter performance, and how comfortable daily life feels on the road. The mistake most people make is starting with a plumbing product instead of starting with how they plan to use their van.
This guide explains how builders think about choosing a water tank so you can make a confident decision without overbuilding or buying the wrong tank first.
Start With How You Use Water Not Tank Size
The best water tank is not defined by gallons alone. Before looking at tanks, ask a few simple questions:
How often do you shower
Do you want a interior shower or exterior shower
How many people are using the van
Do you travel in winter
How often do you want to refill
Your answers matter more than capacity numbers.
Decide Where Water Should Live First
The first real decision is location. Water tanks generally live in one of two places:
- Inside the van
- Underneath the van
Interior tanks are more protected from freezing and simplify plumbing. Exterior tanks free up interior space but require more planning around winter and service access. For more information on undermount tanks, check out our blog that explains undermount water tanks.
Most well designed vans use a combination of both.
Interior Tanks Are Usually Best for Fresh Water
Fresh water benefits the most from being inside the heat of the van and making use of available space onboard.
Wheel well and center mounted tanks are common because they use otherwise awkward space and keep plumbing accessible. They are especially important for cold climate and four season builds.
Sink galley fresh and grey tanks can be great options to keep water onboard and in places close to where they need to be plumbed.
If you plan to travel in winter, interior fresh water is usually the safest choice. For more information on interior water tanks check out our blog that explains wheel well water tanks.
Exterior Tanks Are Often Best for Gray Water
Gray water naturally wants to flow downward. Undermount tanks make dumping easier and free up interior cabinetry. Because gray water does not need to be kept potable, it is often drained or used seasonally in winter.
This is why many vans pair an interior fresh tank with an exterior gray tank.
Understand That Layout Always Wins
Every tank must fit into a layout. Wheel well and center tanks require cabinetry to be designed around them. Undermount tanks have fewer interior constraints but must avoid exhaust heat, suspension travel, and underbody structure. All of the undermount tanks have install instructions and fixed locations pre-determined by factory mounting points.
If you’re looking for a tank by size, to make sure it will fit in your bed system or galley, you can use our water tank configuration here. This configurator also filters by volume.
Common Builder Approved Tank Combinations
Rather than choosing a single tank, builders often choose a bundle.
A 36 gallon center fresh tank paired with a 28 gallon spare tire tank offers high capacity for long trips.
A 24 gallon center fresh tank paired with a 22 gallon driver side undermount balances space efficiency and daily usability.
Both are valid depending on layout and travel style. Check out our blog that compares wheel well and undermount tanks.
Fresh Water Requires a Pump and Accumulator
Any fresh water tank that feeds sinks or showers needs a pump. This is true for interior tanks and even more important for exterior tanks where water must be lifted vertically. An accumulator smooths pressure, reduces noise, and extends pump life. A good option for these is the SeaFlo water pump and accumulator.
Planning for these components early makes the system feel more refined.
Climate Should Influence Every Decision
Interior tanks perform far better in freezing conditions. Exterior tanks can work but may require heating pads, insulation, or seasonal draining.
If winter travel is part of the plan, prioritize interior fresh water and design exterior tanks with flexibility.
Use a Configurator to Visualize the System
Seeing combinations laid out clearly helps prevent mistakes.
The GoCode Overland water tank bundle configurator allows you to explore tank sizes, locations, mounting hardware, and plumbing components together.
It helps you understand how different choices affect layout, winter planning, and overall system balance before committing.
You can explore it here:
https://gocodeoverland.com/pages/water-tank-bundle-configurator
Used as a planning tool, it reduces guesswork and improves outcomes.
There Is No Single Best Tank
The best water tank depends on how you travel, what van chassis you have, and your available space in your build. One important thing to note, is that while other companies exist for water tanks, NW Conversions focuses on making tanks specific to the Mercedes Sprinter, Ford Transit, Dodge Promaster, and Overlanding. These tanks are twice as thick as the standard RV tanks and will hold up in Offgrid missions.
Interior tanks excel at protection and simplicity. Exterior tanks excel at freeing space and handling drainage. Most vans use both intentionally.
Good systems are designed. They are not copied.
Final Thoughts on Choosing a Camper Van Water Tank
Picking the best water tank is about asking the right questions early.
When you consider usage, layout, climate, and serviceability together, the right solution usually becomes obvious. Taking the time to plan now prevents rebuilds later. Check out our blog that lays out how to plumb a camper van.
The goal is not maximum capacity. The goal is a system that fits how you actually live.
