Now, before going on, let me say this. 18 lbs is waaaaayyy above what is actually possible with filling the sink with water. Why, you may ask? I am glad you did. Read on.
If we take a strip 2.5" wide by 15" long, and 10" high.
2.5 x 15 = 37.5 square inches. Multiply that by the 10" high, and we end up with 375 cubic inches. (Length x Width x Height).
We also know there are 231 cu inches in 1 gallon. 1 gallon of water weighs 8.33 lbs.
So, 375 divided by 231 = 1.6233 gallons of water. Multiply 1.6233 by 8.33 for the gallon of water and we end up with 13.522 lbs for weight of water for the 2.5" strip.
However, I am using 18 lbs or 33% more weight than what is even possible. Actually, only 1 corner is 10 inches deep. The center of the sink is only 9" deep so the actual possible weight in the center is about 12lbs. But that's okay. Let's overload it anyway.
