Class A Customs Fresh and Gray Water Tank Installed Fittings

Class A Customs only installs the following fittings into our Fresh / Gray tanks at this time
1.5" NPT Female - fitting is closed
.5" NPT Female - fitting is open
1.25" Outer Diameter x 2" Long Smooth Pipe / Boss Fitting - Spout

For information on custom fittings or placements please use the Water Tank Build Form, please note this option is only available when order 50+ of a tank on single order.


1.5" NPT Female - fitting is closed
use a razor knife to cut membrane out, easiest when cut in halves




Fittings and Hoses We Offer That Fit 1.5" NPT Tank Fitting

Can be used with 1.5" Fitting on tank to connect to 1.375" Hose

Can be used with 1.5" Fitting on tank to connect 1.5" PVC Pipe for draining fresh or gray water tank

1.375" (1-3/8") Food Grade Water Hose
1.375" hose can be used with the fill dishes and the Loose Fitting / Fixture - 1.5" Thread x 1.25" Hose Barb Fitting - Gray
1.375" hose can not be used with spouts on tanks.



.5" NPT Female - fitting is open



Fittings and Hoses We Offer That Fit .5" Tank Fitting

Can be used with .5" Fitting on tank with .5" Hose for Fill Dish Vents and Water Pumps

.5" Hose can be used with the fill dishes vents and the water pumps we sell.



1.25" Outer Diameter x 2" Long Smooth Pipe / Boss Fitting - Spout
glues does not stick to pipe, it can not be sealed or capped
you will need to use the 1.25" Hose with Clamp




Hose We Offer That Fit 1.25" Tank Fitting
1.25" (1-1/4") Food Grade Water Hose
1.25 hose hose can be used with the gravity dishes and spouts/boss fittings on tanks.
1.25 hose does not fit the Loose Fitting / Fixture - 1.5" Thread x 1.25" Hose Barb Fitting - Gray






Where are the fittings located on the tanks?
Are there fittings on both ends of the tanks?

Please look at the photos of each tank as fitting placement can vary by tank, typically fittings are all located on one end of the tank.





How do I get the large fitting out? Are these punch out fittings?
Each tank will come with at least one permanently mounted patch, it is from the manufacturing process, this is not a fitting and does not unscrew.




All water tanks Class A Customs carries must be gravity fed and vented, they are not pressurized tanks.
Have a certified technician install all parts to prevent product damage and personal injury.

A garden hose (a connection from your faucet indoors, etc. anything that pushes the water) is a pressurized water line, do not make a secured connection to the water tank with a pressurized line. Tanks need to be gravity feed, this allows for air to escape while the water is going into the tank. You ca use a Gravity Fill Dish located on the outside of your vehicle to fill the tank, please view the Basic Plumbing Diagram below.
"Venting" the tank lets air move in and out of the tank when in use. Tank must have a large enough opening for air to freely move in and out of tank, if tank is not properly vented tank will explode when filled or implode when emptied. Trying to use a pressurized line "half-way" to prevent damage to the tank will does not work because you can control the amount of water flowing but not the pressure in the line, leaving the tank to fill risks exploding the tank or damaging fittings.





I am going to use a sealed pressurized line to the tank.
This will void any warranty on the tank.
We can easily tell when a tank has exploded due to incorrect usage, you will split the tank or force the fittings out of the tank, again this is not covered under any warranty.



Fill Dish Information

The fill dish is located on the outside of your unit so that you can easily add water to your fresh water tank without the need of opening a compartment or climbing under your unit. The fills dish also includes a small vent that allows you to connect your water tank vent to the outside of the unit, if your tank overflows it will overflow outside your unit. You can find the fill dishes in the Plumbing Category.

For adding water to the Fresh / Gray Water Tank you need a Gravity Fill Dish
the food safe garden hose rests in the fill port on the fill dish - it does not screw onto the port
this is a non-pressurized fill

For using water directly from a food safe garden hose you need a City Fill Dish
The plumbing will bypass your water tank and hook directly to your water heater and faucets.
The food safe garden hose makes a sealed connection on the fill dish and the water supply is pressurized.
This is a pressurized line and can NOT hook to your water tank - pressurizing the tank will cause the tank to explode, fittings to pop-out, cracks to tank, etc.
Units that have metal water tanks can use city fill dishes because the metal tank can withstand the pressure, Class A Customs water tanks can not be pressurized.



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.





For my application I am not using a fill dish.

You can place a larger fitting such as a PVC elbow into the per-installed tank fitting and just rest the garden hose / pressurized line in this fitting, Do not make a secured/sealed connection as this would then be pressurized and would damage the tank. This would then be a gravity fed fill, you can make the same type of fitting set-up for your vent.

  • Be sure to have an additional fitting open at the top of the tank to let air in/out when using the tank, this would be your vent.
  • You can cap the fitting (a) and vent (b) when transporting to prevent water from spilling.
  • Be sure to uncap the vent when removing or adding water to the tank.
  • It is best to have a screen over the vent fitting to prevent anything from entering the tank.





Can I use a water pump with the water tank if I am not using a fill dish?
Using a water pump with the tank pressurizes the water line after the water pump, it does not pressurize the water tank.
Again be sure to have a top fitting on the tank open to let air in when removing water from tank.


You will still need to vent the tank, this can be as easy as placing a fitting with a screen secured over it. Be aware that if you overfill the tank the excess water will exit the vent fitting, placing the vent fitting overflow to an outside location is recommended. Be sure to screen over the vent fitting overflow to prevent anything from entering the tank. Do not over-tighten fittings as damage will occur.

Examples of Items to Vent Tanks - We do not sell these products they can be found online
Oatey® 1.5 in. NPT ABS In-Line Vent
Straight, Black Plastic Tank Vent



Fresh Water Tank Available Connecting Fittings

Class A Customs Basic Plumbing Kit Part # BPK
Designed for Class A Customs Stock Fresh Water Tank set-up using a Fill Dish (fill dish not included)
This is for Fresh Water Systems Only - Not to be used for Gray or Waste Water Systems
Kit does not fit a Spouted Water Tank

Water Inlet Items
Fits 1.5" Tank Fittings - Can be used with 1.375" hose

2 (Two) 1.5” Hose Clamps
Can be used with 1.5" Gray Fitting and Fill Dish

Fits 1.5" Gray Fitting and Fill Dish Inlet
1.375" hose can notbe used with spouts on tanks


Vent and Water Pump Items
Fits .5" Tank Fittings - Can be used with .5" Hose for Fill Dish Vents and Water Pumps we sell

4 (Four) .5” Hose Clamp
Can be used with .5" Barb fitting and/or .5" Hose for Fill Dish Vents and Water Pumps we sell

Can be used for Fill Dish Vents and Water Pumps we sell


Drain Items
Fits 1.5" Tank Fittings - Can be used with PVC Pipe to drain





Gray Tank Available Fittings




Uniseal Fittings


Uniseal Fittings allow the end user to place a fitting anywhere in the tank.
After cutting a hole in the wall of a tank or other surfaces, the seal is inserted. Then the pipe is coated with a slippery detergent and pushed into the seal. The Du Pont Alcryn® is the key to the liquid-tight seal. When the pipe is pushed through the rubber-like Uniseal® from the outside, the inside Alcryn® wall becomes thin enough to allow the pipe to squeeze through and then forms a liquid-tight seal. The coefficient of friction with the plastic pipe is roughly three times higher than any other material, which allows it to create a better seal than with any other material.




Under Sink Gray Tank Set-up Examples
For Gray water tank use you can use any of Class A Customs water tanks, Gray and Waste tanks do not need to be food safe.

To feed directly into the tank you can use a Uniseal Fitting that allows you to place a fitting anywhere in the tank, this is very helpful for concession trailers that want to put the tank under the sink.

Because the Fresh/Gray tanks come with only 1.5" NPT Female fittings and .5" NPT Female fittings built into the tank end user will need to get connecting fittings and adapters that pipe may be installed into.
Depending on the size of the pipe you are using you will need different connecting fittings and adapters, Class A Customs only carries a 1.5" PVC Adapter Fitting - White this may not work for your application, please verify before purchasing.


Additional Examples of Plumbing Set-ups
You will need to verify your needs and set-up, these are examples only, we build our water tanks but do not install them.






Do I need pipe dope or pipe tape to connect the fittings?
It is recommended to use plastic NPT male fittings with the plastic female NPT fittings that are installed in the tank to avoid damaging the threads, metal thread fittings can crush the plastic threads.

Food/Drug Grade Pipe Sealant Pipe Sealant with PTFE EXAMPLE ONLY - We do not sell this item

Very little, if any, pipe thread tape is needed using too much pipe tape will damage the threads. We do not recommend pipe dope as you can not remove the fitting later, if used be sure to use a food safe brand.
Do not over-tighten fittings as damage will occur.


I bought a fitting from my local hardware store and it won't fit.

Be sure you are using NPT fittings and getting the correct sizes. Finding the Correct Pipe Thread Size
You can also print off the items we carry in our Plumbing Category to see if your local hardware store carries them.

Example of Fitting from other suppliers

Clean-out Port

Venting Tanks
Suction Line Strainer that Fits Over 1/2" NPT
Only use this with tanks that will overflow outside of your unit, you do not want to overflow inside of unit.





Waste Water Tank Fitting Information


Waste Water Tank Installed Outlet
Black Waste Tanks - 3” ABS Female Pipe - outlet can not be moved -
Gray Waste Tanks - 1.5" ABS Female Pipe - outlet can not be moved - smaller outlet this tank is for dirty water from shower, handwashing, dish-washing


Waste Water Tank Inlet & Vent
Class A Customs Black Water Tanks only come with the outlet fitting installed, the end user will determine where the inlet and vent will need to be placed and install.

Grommet (not food safe - waste tank use only) or Uniseal (food safe - fresh/gray/waste use) will secure inlet/vent pipe with no adhesives needed.
Use correct size hole saw bit (listed on item page) in order to drill a hole in the tank and place Grommet or Uniseal in hole, piping is then placed in fitting with no glues or adhesives necessary.


Do Not over-tighten fittings damage will occur.

Dump Valves are not connected directly to the Waste Tank ABS Outlet Fitting, the ABS Outlet Fittings are female fittings and the dump valves are also female fittings, they do not connect.
Use PVC or ABS pipe to connect to the 3" ABS Outlet Fitting installed on the waste tank, the dump valve is then connected to the pipe.

We do not sell glues, Examples Oatey 4-fl oz Green PVC/Abs Transition Cement


You will still need to vent the tank, this can be as easy as placing a fitting with a screen secured over it. Be aware that if you overfill the tank the excess water will exit the vent fitting, placing the vent fitting overflow to an outside location is recommended. Be sure to screen over the vent fitting overflow to prevent anything from entering the tank. Do not over-tighten fittings as damage will occur.

Examples of Items to Vent Tanks - We do not sell these products they can be found online
Oatey® 1.5 in. NPT ABS In-Line Vent
Straight, Black Plastic Tank Vent

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