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Under Mount Style 15 Gallon Fresh / Gray Water Holding Tank | UM-1500

Your Price: $57.99

Questions about this item? Ask here.

Part Number: UM-1500

Availability: In Stock. 178

Free Shipping - View Shipping Method Tab Below

Quantity	Price
5 - 9	$56.54
10 - 24	$54.99
25+	$52.99

Quantity

Description
Questions & Answers
Product Features
Preparation & Installation
Food Vendors
Warranty
Shipping Method

Non-Pressurized Tank all tanks we carry must be vented, Basic Plumbing Example

Tank Measurements +/- .25" on each measurement due to manufacturing process

36” does not include fittings x 8.5” x 13” (rotate tank to change height or width)

Average tank thickness .219 or 7/32" thick (just under 1/4")

Installed Fittings See Photos
Two) 1.5" Female NPT Fitting - fitting is sealed to use remove membrane with razor knife

Two) .5" Female NPT Fitting - fitting is open

FAQ's

Additional Fittings

To install additional fittings anywhere on the tank we recommend Uniseal Fittings, you can have from .5" up-to 3"

We do not take orders for custom fitting placements or sizes unless bulk ordering, 100 or more of each tank per order.

Can I get this tank with no fittings installed?

Yes, Class A Customs calls these Blank Tanks.

You will need to verify the lead time on Blank Tanks as we spin the fittings into our tanks as soon as they are made.
If we are currently making a tank we can get you a Blank Tank very quickly, shipping the next business day, however, if we are not currently making a tank it can take up-to several weeks to get a tank.
You can call or use the contact us form to ask about lead times on the Blank Tank you are needing.

When ordering a Blank Tank place the tank(s) you are needing in your cart and at check-out in Customer Comments specify what tanks are to be Blank:
EXAMPLE:
Part # is a BLANK TANK

All Tanks Are BLANK

Can you make me a Custom Water Tank?

We can make a custom tank

You would need to prepay to have a mold made this ranges from $9,000 and up, lead time can be 8 weeks or more.
You would need to place a prepaid PO of a qty of tanks per month/per year, your sales associate would confirm this number, before the mold would be made.
You can fill-out our new Water Tank Build to get a quote on a custom tank.

Our Water Tank List is located at the top of each page with our current tanks.

Q: Do any fittings/hoses come with it? thanks!

Asked by: Ed - 8/30/2022

A: This is the water tank only, we carry fittings in our plumbing category but you will need to verify fittings needed with installer.

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Answer provided by: Customer Service (10/4/2022)

Q: Can this tank be used as a Black Water Tank?

Asked by: Douglas A Schmidtknecht - 9/24/2022

A: Using this tank for any purpose other than fresh or gray water storage will void any/all warranty.

Do Not use Fresh / Gray tanks for sewage or fuel. Do not call to ask can it be used for fuel or sewer, we will only refer you to the warranty information.

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Answer provided by: Customer Service (10/4/2022)

Q: How heavy is this 15 gal fresh/grey water tank?

Asked by: David - 3/14/2023

A: Tank is roughly 12 pounds when empty.

Water weight is 8.34 per gallon, so tank will be roughly 138 pounds when full.

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Answer provided by: Customer Service (5/31/2023)

Q: Will the 15 gal.fresh/grey water tank fit underneath a ford transit 250?

Asked by: Chris - 9/25/2023

A: Unfortunately, we do not have a list of vehicles, uses or projects people have done with our tanks.
Please compare the specs of the tank with your application and determine if tank will fit your needs. Check with online groups that have your same vehicle to see where they have found tanks.

If you are trying to replace a tank that you do not see available on our Water Tank List an online search may help you find the tank you are needing.

Look at current tank to see part #
Vehicle make and model #
Vehicle paperwork listing tank information

*You may not be able to find the same tank, especially in older units.
*You may not be able to purchase from the tank manufacturer unless you are a builder/dealer.

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Answer provided by: Customer Service (9/26/2023)

Q: Do you make delivery to Canada ?

Asked by: Mdesruis - 10/18/2023

A: Class A Customs currently only ships within the US, we do not have any distributors.
Class A Customs does not / will not provide tax information, border or customs paperwork.

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Answer provided by: Customer Service (11/15/2023)

Q: Can you show the locations of the 3 fittings on tank? Mainly the bottom outlet location….

Asked by: Pete - 5/17/2024

A: The photo on the listing shows the location of the fittings on the tank. Thank you.

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Answer provided by: Customer Service (6/27/2024)

Q: Can the holes be made to custom sizes? Also can they be located in different positions?

Asked by: Harry - 6/12/2024

A: Class A Customs no longer offers custom fittings unless you are ordering 50 or more of the same tanks per order.

You can order a tank with no fittings in the tank and then install your own fittings in the location you would like.
Class A Customs calls these Blank Tanks. You will need to call or use the Contact Us Form to see the wait time for Blank Tanks as we do not run all tanks each week.

We offer Uniseal fittings that allow the end user to place a fitting anywhere in the tank, you can find these in the Plumbing Category or by searching the word Uniseal on the search bar located at the top of the website. There will be an installation video on each product page.

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Answer provided by: Customer Service (6/27/2024)

Q: I am looking for grey tanks to go under a school bus-rv conversion. My maximum dimensions are 38" L 33" wide and 32 deep. Could I daisy chain two of your tanks since I cant fit your larger one in the length?

Asked by: Jennifer Rodes - 4/7/2025

A: Can I hook more than one tank together?
Yes, sometimes this is called to "daisy chain" the tanks together. 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.

You can learn more about this on our blog post https://www.classacustoms.com/Class-A-Customs-Plumbing-Example-for-Trailers-Bus-Skoolie-Tiny-House-and-Mobile-Food-Vendors_b_24.html

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Answer provided by: Customer Service (4/11/2025)

Q: Does this undermount work on drivers side of 144 sprinter?

Asked by: Christy - 5/22/2025

A: Unfortunately we do not have a list of vehicles, uses or projects people have done with our tanks.
Please compare the specs of the tank with your application and determine if tank will fit your needs, we will not recommend what items you need or what will work for your application.

You will need to verify if a tank will work for your application, before purchasing review and verify Tank Specs, Photos, and/or CAD Drawing provided on item page.

Each tank is very different in design click the part # to go directly to the item page.
Some tanks have fittings installed in the tank and some do not.
Tanks do not come in left side or right side - the tank you see is the only tank offered.

If you are trying to replace a tank that you do not see available on our Water Tank List an online search may help you find the tank you are needing.

Look at current tank to see part #
Vehicle make and model #
Vehicle paperwork listing tank information

*You may not be able to find the same tank, especially in older units.
*You may not be able to purchase from the tank manufacturer unless you are a builder/dealer.

Was this answer helpful? 0 of 0 Customer(s) found this Answer helpful.

Answer provided by: Customer Service (7/14/2025)

Q: Do the fresh and gray water tanks come with the fittings and hoses

Asked by: JOSE MORUA - 10/26/2025

A: This is just the Water Tank with the installed fittings, please view the item photos and details. Thank you.

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Answer provided by: Customer Service (10/29/2025)

A: This is just the Water Tank with the installed fittings, please view the item photos and details. Thank you.

Was this answer helpful? 0 of 0 Customer(s) found this Answer helpful.

Answer provided by: Customer Service (10/29/2025)

Questions about this item? Ask here.

Made In USA Class A Customs manufactures these tanks and is located in Elkhart, Indiana

Fresh and Drinking Water Safe great for rvs, food vendors and extra water storage

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

NO NSF LOGO Class A Customs NSF Letter (on Water Tank Helps Page) explaining why we no longer have the NSF Logo in our tanks, however, Class A Customs Fresh/Gray Water Tanks are still made from the same NSF Approved Materials.

Forward this letter onto your inspecting Health Department before ordering to be sure tanks will work for your application and get approval.

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)

Non-Pressurized Tank all tanks we carry must be vented, Basic Plumbing Example
Fresh or Gray Water Use ideal for rvs, food vendors and extra water storage
Seamless One-piece seamless construction, no seams to burst
Rotatable tank can be placed on any side
Resistant Stain, Corrosion and Rust Resistant
Color Creamy White in color so you can see waterline through tank
Made From Medium Density Polyethylene (MDPE) Resin - glues do not stick to this material and easily cleaned.

The temperature used during testing is 60 +/- 2°C (140 +/- 4 °F) and appears in NSF Listings Page as "D. Hot". This is intended to apply to product applications where the product is used for either cold (ambient temperatures) or hot water up to domestic hot temperatures.

OEM Part

No retail box - no install instructions

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

Helpful information & answers to common questions can be found on the Water Tank Helps Page

Additional Fittings

To install additional fittings anywhere on the tank we recommend Uniseal Fittings, you can have from .5" up-to 3"

We do not take orders for custom fitting placements or sizes unless bulk ordering, 100 or more of each tank per order.

Custom Water Tanks

We can make a custom tank however due to the cost of a mold ($8,500 and up) most customers needing only a few tanks find it better to use a tank we already manufacture.
For more information and a quote on custom tanks please fill-out our Water Tank Build Form.

Preparation
Sanitize each tank prior to use to remove any debris from the manufacturing process

Tanks are made in a warehouse, wipe with a damp cloth to remove surface dust or scuffs

Installation & Plumbing
Non-Pressurized Tank all tanks we carry must be vented allowing air in and out when in use, Plumbing Examples
Do Not hook a garden hose directly to tank damage will occur, it is recommended to use a fill dish or other gravity process
Do Not over-tighten fittings as damage will occur.

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

What fittings will I need for my plumbing?

This will depend on how you are setting-up your tank and will vary by application, we are not aware of what items you will be needing, please view the Plumbing Examples

Food Grade Fill Hose

Uniseal Grommets

Water Tank Monitors & Probes

Mounting & Bracing
Tank can be placed on any side.
Place tank on level surface and brace to prevent tank from moving during transit.
Tank needs to be adequately supported, examples on the Water Tank Helps Page
Do Not hang by ratchet straps, this is too thin and will not adequately support tank.
Do Not place weight on tank, if you need to stack the tanks you will need a weight bearing shelf between them.

Can I install the tank under the trailer?
Tanks can be installed inside or outside of unit, for food vendors verify requirements before purchasing as some areas do not allow tanks to be outside of the unit and others do not allow the tank to be inside of the unit.
Be sure to Sanitize Tank before installing.

All tanks must be braced and secured to prevent any movement of the tank while in transit and to prevent possibility of tank tipping or falling.
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 to help with drainage) 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. For tanks placed outside it is also recommend to enclose tanks using sheet metal / plywood or some other type of weather proof material to prevent damage from road debris and speed bumps, be sure to check your clearance before ordering.

Brackets or Strap Systems Due to the variety of installations we do not carry brackets or bracing systems.

Before you build or modify unit, you need to verify rules and regulations.
Codes vary by local health departments, not state.

We are not aware of the codes or rules. We are not aware of what tanks or items you need.

Ask your inspector BEFORE purchasing

Size Requirements (Gallons / Measurements / Fresh to Gray ratio)

Does the bottom need to be slanted? Can I place the tank on a slanted surface as this would make the tank then slanted?

Fittings Requirements (Size / Placement / Materials)
Filling Procedure Requirements (Lockable Fill Dish / Materials)
Tank Placement Requirements (Inside / Outside of unit)

Clean Out Requirements Do I need a clean out? What size does this need to be?

Class A Customs Tanks have NO NSF LOGO - read below for why

Water Tank Percent Calculation Examples
Multiply (fresh tank size) x 1.15 (1 . 15%) = Tank needed
30 x 1.15 (15%) = 34.50
30 x 1.50 (50%) = 4

NO NSF Logo
Tanks no longer have the NSF logo molded into them due to changes NSF made regarding the use of the NSF logo. The NSF Company does not allow for end users to use the NSF logo unless each item has been inspected and a certification paid for each item, the material that all of our tanks are made from are still the same NSF Certified Material, adding this extra step of certification is an unnecessary step but generates revenues.

The NSF Company does not allow vendors/manufacturers to link to the NSF paperwork unless verified NSF products are being used, our company has been verified and therefore is allowed to link to the NSF Certified Materials on the NSF Website. If needed your inspector can check on this regarding our company and website as we have already provided this information to the NSF company and have been advised on how to correctly use/link to the certification information on our website.

What does my inspector need when I go to inspections on the tanks?
Class A Customs NSF Letter (on Water Tank Helps Page)
Receipt of Purchase
All tanks have the part number molded into the tank, inspector can verify tank.

Manufacturer Warranty

Class A Customs, LLC Manufacturer Warranty covers manufacturer defect on manufacturer installed fittings and tank workmanship.

Inspect tank and all fittings before beginning installation, there is a 14 (fourteen) day time period to report any damages once you items are received.

Warranty does not cover tank or fitting damage resulting from tank or fittings plumbing being jarred, moved, cracked, cross-threaded, damaged threads from use, and/or fitting punched from tank. Such damage is due to plumbing being moved and/or tank being jarred causing unavoidable damage beyond manufacturer control or responsibility.

Warranty does not cover cross-thread damage, fittings are injection molded not carved, so threads can not be cross-threaded from manufacturing, cross-threading only occurs from incorrect use of fitting.

Warranty does not cover tank or fitting damage due to customer improperly venting tank.

Warranty does not cover damage to tank from weight being on tank or tank being compressed by outside forces, example, tank being buried underground causing collapse; tank being compressed under boat.

Warranty does not cover damage to tank or fittings due to weather related incidents, example, tank freezing or being in excess heat/sun expose.

Using Class A Customs, LLC Fresh/Gray Water Holding Tank for any purpose other than fresh or gray water storage will void any/all warranty.

Using Class A Customs, LLC Black/Gray Waste Water Holding Tank for any purpose other than black (human waste) or gray water storage will void any/all warranty.

Using any Class A Customs, LLC water tanks for fuel, chemical or other storage voids warranty.

30 Day Return Policy
Some items are nonreturnable and include but not limited to:
All Fuel Pumps
Electrical Items
All Water Pumps

Customer will need to return all merchandise in new, unused condition and packing materials if available.
To return item customer will need to pay return shipping. Packages refused or return to sender will not be delivered back and no credit/refund will be issued.
Original Shipping is non-refundable, 20% Restock fee will be charged for all orders.

Returns c/o Class A Customs
1130 County Road 6 West
Elkhart, IN 46514
Phone: 574-206-0101

Include a copy of original purchase receipt and write order number on each box
Save the tracking numbers for your records, we are unable to search for a package online without tracking numbers.

Return Process
This time period includes the transit time for us to receive your return from the shipper (5 to 10 business days), the time it takes us to process your return once we receive it (3 to 5 business days), and the time it takes to return the correct item. We'll notify you via e-mail of your refund once we've received and processed the returned item.

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