Water Fresh or Grey water holding tank.
I was going to build in my Camper van build, went another direction.

$48.49 plus shipping on classacustoms.com-- $35 for you here.

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

Tank Measurements +/- .25" on each measurement due to manufacturing process
19” does not include fittings x 9” x 14” (rotate tank to change height or width)

Installed Fittings:
Two) 1.5" Female NPT Fitting - fitting is sealed to use remove membrane with razor knife
Two) .5" Female NPT Fitting - fitting is open

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
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)

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.

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