The size of the tank is another significant determinant of price. Fibreglass water tanks vary from small 100-gallon tanks suitable for residential use to large 10,000-gallon tanks that cater to agricultural or industrial needs. The larger the tank, the higher the price, with larger tanks often requiring additional structural support and materials. For instance, a 1,000-gallon fibreglass tank might cost anywhere from $1,200 to $2,500, while a 5,000-gallon tank could range from $2,500 to over $7,000.