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Water Tanks for Mobile Detailing (Setup and Size Guide)

Even with many detailers using less water than they used to, a water tank is something that you really should think about as a mobile detailer. These come in a variety of sizes and shapes, and there are a few things to consider before purchasing one for detailing.

Unless you plan to purchase a water tank from a detailing store (that usually includes a tank, pump, skid, etc.) it’s really quite easy to replicate one of these setups and save you a ton of money.

In this post, I’ll break down a few common sizes, accessories to pick up, and a few tips along the way when setting up everything.

Step 1: Select the right tank size for detailing

rectangle water tank detailing

If you are working out of a van or trailer, the tank size you need depends on how many customers you serve. Smaller water tanks are not too expensive compared to most other equipment you will need for detailing, so most people usually start with something smaller.

You can usually find a good selection of water tanks at your local farming supply store, but I found a few online that were pretty reasonably priced.

Below are a few tank sizes to consider based on your business model and the number of vehicles you normally wash.

Keep in mind: The number of cars you can expect to wash assumes you aren’t using ONR or a rinse-less wash system. For maximum gas mileage, you probably want to start by only filling your tank halfway, or with enough water for a day’s work.

50 Gallon Water Tanks

A 50-gallon tank is probably the smallest I would go with and can be found for around 100 bucks. This rectangular model I found on Amazon for around that price the last time I checked.

RomoTech 50-gallon Water Tank

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  • Number of Vehicles you Can Expect to Wash: 1-2 cars, depending on how dirty it is.
  • Weight when 100% full: 417 lbs

100 Gallon Water Tanks

A 100-gallon tank is probably one of the most common I see in detailing and is a good size for using a pressure washer. This thing weighs nearly 1,000 pounds when full of water, and just large enough that you may feel a little trailer sway if it is full of water.

This one on Amazon was a couple of hundred bucks and about the cheapest this size I could find.

RomoTech 150-gallon Water Tank

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A 100-gallon tank should last you an entire workday for most people that have a team of a couple of people.

  • Number of Vehicles You can Expect to Wash: 4 to 5 cars
  • Weight when 100% full: 834 lbs

250 Gallon Water Tanks

For most detailers, a 250-gallon tank is going to be more than you really need, but if you have a dual-axle open trailer that can handle the weight, it’s something to consider. With any of these tanks, I would not top them off. Water weighs 1 gallon of water weighs 8.34 pounds, so always make sure your trailer is capable of supporting the weight.

  • Number of Vehicles You can Expect to Wash: 10-12 cars
  • Weight when 100% full: 2,085 lbs

Step 2: Secure your tank

metal water tank straps

While you’re at it, it’s essential that you figure out a safe way to secure your tank to your truck bed van, or trailer. The most common method I see is by using ratchet straps secured to heavy-duty suspension anchor hooks that can be attached to your trailer bed or frame.

anchor hooks detailing water tank

You can find these on Amazon here or at your local hardware store, which can hold up to 1,450 pounds. They’re normally used for mounting swings.

They also make steel straps that fit rectangular tanks that you can find. I personally like the ratchet straps, since it makes it easier to remove the tank if you need to.

Most tanks will be either rectangular or cylindrical, but you may see a few that are circular.

Step 3: Set up your tank

This is the most important step. To effectively draw water from your tank you can either keep your pump elevated in your van (about 1 foot) to let gravity feed into your pressure washer or use a pump. While some guys use a gravity-fed system, I would recommend using a 12-volt pump to draw the water out.

Below are a few steps for assembling a typical water tank/pump setup. There are many configurations, but this one seemed to be one of the most common I have seen.

  1. Secure your water tank with the opening facing the rear.
  2. Attach a 1 1/4-inch bung to the opening at the bottom of the tank
  3. Attach a brass shutoff valve to the bung
  4. Attach a 1 1/4 inch hose to the shutoff valve, connecting your bung to a jet pump (or other pump)
  5. Connect a hose from your jet pump to the pressure washer
  6. Connect a hose from your pressure washer to hose reel
  7. Start your gas pressure washer or electric pressure washer and generator.

Any 12-volt pump should work, but if the pump can hold water, you won’t have to worry about priming it. The video below I thought did a great job explaining this:

Step 4: Buy accessories for your tank

While you want to make sure you get a high-quality tank that will survive the wear and tear of a detailing business, there are other accessories you’ll need to pick up in order to pump water to a pressure washer or hose.

Here are a few items to consider buying with your tank:

  • (2) Ratchet straps to secure to the floor
  • (4) Truck and trailer 1,200 lb capacity anchors. Drill these to your floor or frame, and secure ratchet strap hooks.
  • (1) 12-volt pump. Shurflo is one of the better 12V pumps I’ve heard detailers use, and can be found here on Amazon.
  • (2) 4-foot water braided hoses for connecting tank to pump and pump to pressure washer
  • Metal hose clamps where needed for attaching hoses.
  • A base for securing your tank

Of course, there are several other products you will need if you are just getting started with your setup. Check out my post Building a Skid Unit for Detailing for a basic idea of what to use.

Step 5: Fill your water tank and keep it clean

fill water tank for detailing

When filling your tank, tap water is usually okay, but if you live in an area with very hard water you may want to consider a de-ionized water system. Check out my post on the benefits of portable deionized water systems if this is something that is a problem. Even if the water dries before you can blow it off or wipe it up, it shouldn’t leave any water spots.

Avoiding algae and mold

Cleaning your tank may seem like an afterthought at first (it did for me) but is important for keeping the water safe for your health and for a car’s clear coat.

Being in the back of a hot van or trailer can sometimes lead to algae when working in hot summer conditions, so using a diluted bleach mixture is a good idea periodically to flush everything out. While most water tanks are white, it’s not a bad idea to try to find a dark color or opaque tank that you can’t see through.

Darker color tanks prevent light from entering your water supply, which can make it more difficult for algae to grow. You may even want to spray paint your tank with a paint that can stick to plastic, taping off a section to view your water line.


Overall, I would opt for purchasing a tank size that will allow your detailing business to grow while not being too large for your trailer or van. Most of the time, a 100-gallon tank is a good choice for most people. Heavier 250-gallon tanks can cause quite a bit of trailer sway, and is not a great idea unless you have to equipment to haul it around.

Many detailers use pretty minimal amount of water these days, but it depends on if you are washing fleets, or live in an area with water restrictions. Let me know if you have anything to add that worked for you when getting everything set up.

Baxter Overman is the founder of Carwash Country and has been been cleaning up dirty vehicles for nearly 20 years. Since 2017, he's helped thousands of beginners see better results by learning the fundamentals of washing and detailing. He's on a mission to make the car wash process more fun...and way easier.

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