The water tank of your RV is the lifeblood of all water sources throughout your rig. So, it's important to not settle for something standard. You don't want to be taking a shower only to have your water run out halfway through. No one wants a sink full of dirty dishes, either! Choosing the right tank to fit your needs is important, which is why it's equally-important to know what you're getting into when buying the right water tank. T165 You won’t have to venture far to find the potable water you need as long as you have access to RecPro’s 21-gallon RV Fresh Water Tank. This 39” x 16” x 8” tank is constructed using strong high-quality polyethylene material, a material that carries FDA approval. Dimensions Dimensions: 39" x 16" x 8" Material: Polyethylene Wall thickness: 1/8" Inlet - 2" long Inlet - 7/8" Internal Diameter (smooth barrel) Outlets - 3/8" The water tank of your RV is the lifeblood of all water sources throughout your rig. So, it's important to not settle for something standard. You don't want to be taking a shower only to have your water run out halfway through. No one wants a sink full of dirty dishes, either! Choosing the right tank to fit your needs is important, which is why it's equally-important to know what you're getting into when buying the right water tank.