~ Shipping ~
Class A Customs at this time does not ship outside of the US.
Free Shipping Items Standard Shipping to U.S. addresses in the 48 Contiguous U.S. only.

Orders are processed next business day. If you are needing to cancel an order be sure to receive a confirmation by the Contact Us From or order will be processed.

~ Custom Tanks ~
Can you make me a custom tank?
We can make a custom tank however you would need to pay for a mold ($3,000 - $8,000). For more information you can email a CAD drawing or spec sheet and a sales member will contact you.

Due to increased sales we are no longer able to offer custom fittings on water tanks.

If you are a manufacturer or OEM needing custom fittings please contact sales for more information, minimum quantity of 50 tanks will apply.

Other Water Tank Suppliers





Class A Customs Water Tank Information

Fresh / Drinking Water Safe

BPA FREE – Class A Customs does not carry this chemical nor uses it in the manufacturing process

NSF Certified Materials Tank & fittings made from DOW NSF International NSF/ANSI Std 61 approved Medium Density Polyethylene (MDPE) Resin

UV-8 stabilization

Complies with:

U.S. FDA 21 CFR 177.1520 (c)3.1a

Canadian HPFB No Objection

Underwriters Laboratories Inc.

EU, 10/2011

NSF International NSF/ANSI Std 61 (sec 4 & 5)


You must verify requirements with health department where inspection will be made before purchasing.

Forward the documents provided to your local health department before purchasing to be sure these tanks will pass your local inspection, this is your responsibility.

Codes vary by local health departments, not states, we are not aware of the codes.

Fresh Water Tank
Size (Gallons / Measurements)
Fittings (Size / Placement / Materials)
Filling Procedure (Lockable Fill Dish / Materials)
Tank Placement (Inside / Outside)

Gray Water Tank

Size (Gallons / Measurements - Health Departments require the Gray tank to be larger than the Fresh)

Fittings (Size / Placement / Materials)

Drainage (Fittings / Placement)

Tank Placement (Inside / Outside)

Gray Water Tank Calculation

Multiply (fresh tank size) x 1.15 (1 . 15%) = Tank needed

30 x 1.15 (15%) = 34.50

30 x 1.50 (50%) = 45

I have only so much room how many gallons can I get in that space?

We do not recommend sizes or verbally give measurements please look at the Water Tank List located at the top of each webpage to see all tanks Class A Customs currently manufactures.

How are the water tanks measured?

Please be sure to look at the photos provided with each item as measurements and fitting placements will be included. Note the measurement of the tanks do not include the fittings, this will add extra length to the tank.

Do you have a list of water tanks used in vehicles?

No, we do not have a list or way to cross reference what tank you have or had in your unit when manufactured, check with the vehicle manufacturer or look for part number on tank.

Do you know if someone has used a _____ tank in a ______ ?

No, we do not have a list of vehicles, uses or projects people have done with our tanks.

~ Fittings ~

Due to increased sales we are no longer able to offer custom fittings on water tanks.

If you are a manufacturer or OEM needing custom fittings please contact sales for more information, minimum quantity of 50 tanks will apply.

Where are the fittings located in the tank? What kind of fitting are in the tank?

Our Stock Tanks come with 4 fittings all located on the same side of the tank. Be sure to look at the tank photos and description to clarify fittings.

Can I cut a hole in the tank and glue another fitting in?

No, fitting are spun welded into the tank, friction between the fitting and the tank causes both to melt and permanently seal, no additional glues or sealants are used to install the fittings.

The residue left by putting the fittings in place is part of the material the tanks and fittings are made from and may spider crack or flake off over time, this in no way harms the tank or causes any usage issues.

Uniseal Fittings Now Offeredfor more information go to our Blog Post Custom Tank Fittings Now Available

Is that a fitting or a clean-out on the side?

Each tank will come with at least one vent hole made during the manufacturing process, a permanently mounted patch is placed over this hole this is not a fitting and does not unscrew.

~ Plumbing ~

Have a certified technician install all parts to prevent product damage and personal injury.

All water tanks we carry must be vented, they are not pressurized tanks.

You must allow air to move in and out when filling and emptying the tank. Do NOT fill the tank directly from a pressurized line (garden hose), this is not a safe option and will explode the tank. We recommend using a fill dish to allow for gravity feeding of the tank, please review our plumbing example for more information.



What fittings will I need?

This will depend on how you are setting-up your tank and will vary by application. Please view our Plumbing Category for information on loose fittings we carry.

At this time Class A Customs only installs the following fittings into our Fresh / Gray tanks

.5" NPT Female

1.5" NPT Female

1.25" Outer Diameter x 2" Long Smooth Pipe (Boss Fitting)

It is recommended to use plastic male fittings with plastic female fittings to avoid damaging the threads, metal thread fittings can crush the plastic threads.

.5" fitting can be used for air vent and water pump

1.5" Fitting can be used for water inlet or drain

1.25" spout fitting can be used for water inlet or drain

National Pipe Threads (NPT)
Pipe sizes do refer to physical dimensions, but the plumbing industry standard for the sizes of pipe is not always as straight-forward as measuring the pipe. Measuring the pipe will oftentimes mislead you into choosing the wrong pipe, so do take care. The "pipe thread size" as shown in column 3 of the table below is measured and based on the inside of the pipe. But, to actually determine the size of a pipe, the outside diameter of each pipe or fitting must be measured and compared to the table for size identification. For example, a 3/4" NPT pipe thread has an outside diameter of 1.050 inches. Each thread size has a defined number of threads per inch (TPI). The 3/4" NPT pipe thread has 14 threads per inch. Both the TPI (threads per inch) and OD (outside diameter) of the thread are required for positive identification of thread size because several sizes have the same TPI.

Male threads: Measure the outside diameter of the large portion of the thread at "A"; Find figure nearest this dimension in column 1 or 2 of chart. The dimension in column 3 will be your nominal pipe thread size.

Female Threads: Measure top diameter of thread at "B"; Find figure nearest this dimension in column 1 or 2 of chart. The dimension in column 3 will be your nominal pipe thread size.

Q."What does 'nominal' mean?"
A. Nominal is the term used to describe pipe and fitting measurements in plumbing. Nominal refers to the inside diameter of the pipe which varies by wall thickness of the pipe.

Q."Ok, so IPS pipe sizing isn't actually a dimension. So what about the fittings?"
A. Pipe fittings are "sized" by the "size" pipe they fit. So, for example, a 1/2" IPS fitting would fit 1/2" IPS pipe.

National Pipe Threads (NPT) have tapered threads. These are the most common threads used for general purposes. NPT threads are designed with a 60 degree thread angle, and are used for joining and sealing pipe to fittings in low pressure air or liquids and also mechanical applications. The tapered thread is 3/4" over one foot of length. Tapered threads are deeper at the end of the pipe and are increasingly shallower the further they are from the end of the pipe. The taper on the pipe only allows the pipe to screw inside the fitting until it is forced to stop because of the taper. The distance the pipe can be screwed into the fitting is specified by the ANSI standard. After tightening with a wrench the threads may have slight spaces between the pipe and fitting which could cause a leak so a pipe sealant must be used to ensure any gaps are filled.

The Dry-seal thread (NPTF) also have tapered threads. NPTF threads are used when the application is such that pipe sealing compounds may fail due to higher heat or pressure than normal NPT threads can withstand. The threads are designed to seal mechanically by slightly, but sufficiently, crushing the threads when tightened with a wrench. This allows for joining the pipe and fitting without sealants.

The NPT and NPTF threads can be interchanged if sealants such as PTFE tape or suitable pipe joint compounds are used. None of the other thread standards are fully interchangeable (GHT, NST, BSPT, NPSI, etc.) Female NPT threads can be designated as "FPT" or "FIP" and male NPT threads can be designated as "MPT" or "MIP".

National Standard Free-Fitting Straight Mechanical Pipe Threads (NPSM) have straight threads which are only used for joining. A washer or gasket is needed to seal this type of threaded connection.

There are also three less common thread types used in the plumbing industry. The Garden Hose Thread (GHT) and the Fire Hose Thread (NST) have coarse threads. The seal is made with a gasket or washer and are used mainly for attaching (joining) hoses to valves quickly, without the use of a wrench. The British Standard Taper Pipe Thread (BSPT) has a 55 degree thread angle (NPT are 60 degree) and is used internationally as a standard thread for joining steel pipes.

~ Fill Dish ~

What is a fill dish?

The fill dish is located on the outside of your unit so that you can easily add water to your tank without the need of opening a compartment or climbing under your unit. You can find the fill dishes in the Plumbing Category.

For adding water to the Water Tank you need a Gravity Fill Dish, the hose rests in the port it does not screw onto the port this allows you to place a garden hose into the Gravity Fill Dish port without making a sealed connection so the supply is not pressurized.

For using water directly from a garden hose you need a City Fill Dish, the hose makes a sealed connection and the water supply is pressurized, you can not hook this to your water tank and you do not need to go through your water pump.

We carry Gravity Fill Dishes, City Fill Dishes and Combo Fill Dishes that have both gravity and city, the benefit of having both is you can have a water tank of fresh water but if you go to a location that supplies pressurized water (campground - fair - etc.) you do not need to use your water tank supply of water you can simply use the water provided. Be sure to look at the provided example plumbing diagram for more reference.

But what if I only turn the garden hose on half way?

Customers who do this still explode the tank because you can not determine the pressure of the water flowing only the amount of water.

I am not using a fill dish how can I fill the tank?

We recommend you place a fitting in the tank that will allow you to rest the hose in to fill, not make a sealed connection, you can then cap this when not in use. You can use an elbow fitting to allow you the fill the tank to capacity, use an elbow with a screen secured over it to vent the tank.

Can I put a cap on and off of the tank?

If you are needing to use a fitting by adding and removing a cap, remember tank must be vented allowing air in/out during use, we recommend you place a fitting in the tank and a cap on that fitting in order to prevent damage to the tank fitting.

~ Monitor Panels & Water Tank Probes ~

Water Tank optional Installed Water Tank Probes, Loose probes are available for customer installation.

For Step-by-Step Photos visit our Blog Post Water Tank Monitor Probes

Monitor Tank Installation Help

~ Installing & Bracing ~

The tank looks like the side is bowed, is it safe?

Due to the manufacturing process all the tanks especially the larger in size will have a bowing to the walls, when the tank is filled the tank will expand out removing the inward bow, we recommend laying all tanks on a level surface (this can be angled) and bracing the tanks. For larger tanks it is recommended to brace all side walls with plywood or metal, we do not recommend using ratchet straps on the tanks alone as this is a large amount of weight on a thin strip and may cause cutting into the tank.

Tank Average Thickness

All tanks will vary on thickness but on average they are .219 or 7/32" thick.

Can I stack the water tanks on top of each other?

No, do not place anything on the tanks, if you need to stack the tanks you will need a weight bearing shelf between them.

Do I need to brace the water tank?

It is recommended to brace all side walls with plywood or metal, we do not recommend using ratchet straps on the tanks alone as this is a large amount of weight on a thin strip and may cause cutting into the tank.

Can I set the tank up on end?

Yes, you can place the tank on any side, you will need to brace the tank and run a food grade pipe or hose down inside to reach the bottom of the tank. For easier use fittings can be moved and additional fittings added. You will need to fill-out the tank form to show the placement and once confirmed your order will be processed the next business day.

Can I mount the tank under the trailer?

For those getting inspections you will need to verify with your local health department if you are allowed to place the tank outside of your unit. For all other applications we recommend having the tank sit on a level surface such as plywood or sheet metal then bracing it with bars or straps, it is helpful to fully enclose the tank to prevent damage from rocks and debris during travel. Be sure you check clearance to avoid having the tank removed on a speed bump or curb.

Can I hook more than one tank together?

Yes, you will need to check with a certified plumber to see what fittings and set-up will work best for your unit, remember to vent each tank.

~ Sanitize Tank ~

When I get the tank what should I do first?

Sanitize each tank prior to use to remove any debris from the manufacturing process. Tanks are made in a warehouse so maybe dusty or scuffed, this does not effect the use or safety of the tank, wipe with a damp cloth to remove surface dust or scuffs.

Make Water Safe - Click to Download

1. Prepare a chlorine solution using one gallon of water and a ¼ cup of household bleach (5% sodium hypochlorite solution)


Never mix bleach with ammonia or other cleaners.

Open windows and doors to get fresh air when you use bleach.

With tank empty, pour chlorine solution into tank. Use one gallon of solution for each 15 gallons of tank capacity.

2. Complete filling of tank with fresh water.

3. Allow to stand for three (3) hours

4. Drain and flush with potable fresh water.

Any residual chlorine odor will dissipate naturally.

~ Waste Water Tank Help ~

Customer will measure and determine where inlet/vent will be placed on Black Waste Tank.
Use correct size hole saw bit in order to drill a hole in the tank and place rubber grommet in hole. Rubber grommet will secure inlet/vent pipe with no adhesives needed.

Included are a few short videos displaying the grommet installation process.