When it comes to building a custom van, deciding where to install your freshwater and gray water tanks is an important decision that can impact your comfort and convenience on the road. In short, there are quite a few factors you’ll need to consider before making the decision, and pros and cons with each route. For more details on the factors to consider when choosing the tank see: What to consider when choosing a water tank for a custom van build? That said, a few key variables specific to choosing a location for your tank include:
Space is limited
One of the most significant factors to consider when deciding where to install your freshwater and gray water tanks is space. Custom van builds are all about maximizing the available space, and every inch counts. Installing your freshwater tank inside the van can take up valuable space that you could use for storage, a bed, storing gear or other living essentials. On the other hand, installing it underneath the van frees up interior space, allowing you to make the most of your living area.
Expected climate will dictate your tank location
Weather is a critical consideration and one of the most important when deciding where to install your freshwater and gray water tanks. Installing your freshwater tank inside the van protects it from external weather conditions, such as extreme heat or cold. However, installing it underneath the van leaves it exposed to the elements. If you plan on traveling in extreme weather conditions, such as in the winter, you may want to consider installing your freshwater tank inside the van. Tanks are quite prone to freezing, and even with sufficient insulation outside the van, they can be difficult to manage in the winter. Some van builds will incorporate the use of multiple tanks both inside and underneath to accommodate their multi-season lifestyle. That said, generally, for vanlifers expecting to endure winter conditions, indoor tanks are a must.
Water tanks are incredibly heavy when full - this will impact your location choice
Another important consideration is weight. Water is heavy, and carrying a large amount of water in your van can significantly impact your gas mileage and the overall weight of your vehicle. Each particular van has a payload capacity or rating, and it’s important to keep this in mind when choosing a tank, and installing. Similar to standard trucking technique, often heavy objects like full water tanks are best positioned closest to the cab. Realistically in a van build, it may not be worthwhile to adjust your entire build around the optimal location for a water tank to slightly improve vehicle performance - but something to think about. Further, when considering weight, think about ensuring that the location you choose for your tank can support the weight of a full tank. Your tank will be traveling at 60MPH in some cases, with potentially hundreds of pounds of water - is the location you’re choosing capable of adhering strong supports to effectively hold the tanks in place? For instance, if installing underneath the van, can you drill in the desired location, and is there space to add steel beams without interfering with core vehicle operations?
Some spots for tanks are more accessible than others
Accessibility is another critical factor to consider when deciding where to install your freshwater and gray water tanks. You want to be able to access your freshwater tank easily to fill it up and perform routine maintenance. Installing your freshwater tank inside the van makes it easy to access, but installing it underneath the van can make it more difficult to reach. However, if you plan on living in your van full-time or for extended periods, you may find that having a larger freshwater tank is worth the trade-off of accessibility.
Difficulty of installation varies across water tank location options
Finally, installation is another important consideration. Installing your freshwater tank inside the van is generally easier than installing it underneath the van, as it does not require drilling a hole in the van's body for the fill port. However, installing it underneath the van can be more challenging, as you need to find a suitable location that is protected from the elements and secure enough to hold the tank in place.
The type of tank you want to install impacts where you should install it
When deciding where to locate your tank, you should already know what type you need - is it going to be a freshwater, gray water or black water tank? Each of these has slightly different needs and pros/cons in terms of locations, so it may impact your decision.
Pros and cons of installing your tank inside the van
Pros:
Easier access to the water source: When you install your tank inside the van, you have easy access to the source. If it’s a freshwater tank, you can fill up your tank from the inside of the van (or by simply opening the door), which is much more convenient than having to go outside or climb underneath to fill it up. If you’re installing inside the van, you’ll likely choose a smaller tank, in which case you’ll fill up more frequently, so ease of access may become more important. If you’re planning to install a gray or black water tank, installing inside means it will be easier to dispose of the contents (you won’t have to crawl under the van). Some people who choose to install gray or black water tanks inside end up drilling through the floor so they don’t have to physically carry the tank outside to dispose - this depends on the size of your tank and how often you’re dumping. While installing gray and black water tanks inside may make the disposal process easier in some cases, it doesn’t come without disadvantages as we discuss below.
Protects the tank from external weather conditions: This is likely the biggest positive for installing the van inside, and likely a major factor why people do so. When you install your tank inside the van, you protect it from external weather conditions, such as extreme heat or cold. This can help to prolong the life of your tank and prevent it from freezing in colder climates. This factor is relevant for fresh, gray and black water tanks. For freshwater tanks, you obviously don’t want to have your water source freezing frequently, as you’ll need it for showering, drinking, cooking and cleaning. Gray water tanks freezing aren’t as critically serious, but are still quite inconvenient, meaning that if your gray water tank freezes you’ll still be able to survive, but it may lead to a backup in your water system, and prevent you from fully draining or even continuing to use water. Black water tanks are similarly inconvenient if they freeze, because they can crack, leak, or lead to buildup of sensitive contents. All to say, keeping tanks inside and reducing risk of freezing can certainly be a positive.
No need to drill holes in the van's body: If you’re installing inside the van, it makes the plumbing easier, as it’s one less time (at least for each tank) you’ll have to drill through the metal floor to connect your pipes to your sink, shower, etc. You also likely won’t have to drill through the van for a fill port, which can similarly save you time, effort and probably money.
Cons:
Takes up valuable interior space: This is the biggest issue with installing inside the van, and can outweigh all other factors in many cases. Installing your tank (or tanks) inside the van takes up valuable interior space that you could use for gear, storage, a bed, or other living essentials. If you have a small van or plan on living in your van full-time, this can be a significant drawback.
Potential for leaks and spills inside the van: Installing your tank inside the van can increase the risk of leaks and spills inside the living area, which can be unpleasant and potentially damage your van's interior.This is of course more serious for your gray and black water tanks, where leaks can involve damaging or disgusting contents.
Pros and cons of installing your freshwater tank underneath the van
Installing your freshwater tank underneath the van also has several pros and cons, which we'll explore in more detail below.
Pros:
Saves space: This is a major benefit. Installing your tanks underneath the van frees up a substantial amount of interior space, allowing you to make the most of your living area. Of course this is more important if you have a smaller van or plan on living in your van full-time.
Does not interfere with the van's interior design: Installing your freshwater tank underneath the van does not interfere with the van's interior design, allowing you to create the living space that best suits your needs and preferences. Installing tanks underneath can be a complete game-changer for space, allowing you to fit full bicycles, try a totally different bed design, and more.
Limited downside from leaks: While you may not notice leaks as quickly, this is a good thing. Any issues with your tanks or the adjacent piping will simply leak outside, with no risk of damaging your hard work or appliances. This is a pretty strong benefit, but if you’re confident in your plumbing skills, you shouldn’t expect leaks anyways.
Cons:
Vulnerable to external weather conditions: Installing your tanks underneath the van leaves it exposed to external weather conditions, such as extreme heat or cold. This can lead to freezing in colder climates and potentially damage your tanks - as we discussed, the implications for this are different across fresh, gray and black water tanks. That said, freezing in your tanks is never a positive, so really worth considering if you’re planning to travel through colder climates. There are some ways you can slightly reduce freezing through insulation and protection, but at the end of the day if you’re in freezing conditions, it’s going to be likely that your tank performance dwindles.
Can be challenging to access: Installing your tank underneath the van can make it more challenging to access for maintenance and repairs, as you need to crawl underneath the van to reach it. Beyond maintenance and repairs, you’ll also have to think about water fill-up and disposal; how frequently do you expect to have to do this, and is it a huge pain for you to crawl under? Keep in mind there are solutions to allow for remote or electronic disposal access - preventing the need to physically get under the van to access your tank. There are also ways you could arrange your piping to allow for a more convenient fillup (extend pipes out from under van on the exterior of vehicle). If you’re set on slinging your tanks underneath your van, access can be a challenge but there are ways to work around it.
More prone to damage / durability issues: Most tanks you see are relatively durable now, but something to consider. Your pipes, and tank will be fully exposed to the road, bumps, flying rocks and more. If you’re intent on appending your tanks underneath your van, be sure to use very durable pipes, fittings and tank material.
More difficult to install: Installing your water tanks underneath the van will likely require cutting through the van’s metal floor at least once for each tank. You’ll also have to drill into the van’s bottom to attach (and build) a structure that can support the heavy weight of water traveling at high speeds. This certainly isn’t impossible, as tons of people do it, but just another project for your list.