Front Runner Upright Water Tank / FlatProduct Description A 40l (10. 6gal) water tank that is perfect for showers, drinking, and cooking. This slim upright water tank fits inconspicuously behind the rear seat of your vehicle. For showers, drinking, and cooking, this slim upright water tank fits inconspicuously behind the rear seat. The fact that it is of such a slim design reduces the water sloshing noise and allows it to utilize space that would usually go to waste. 40l (10. 6gal)