i am trying to make a tub of hot water in my game but i keep on getting that error at line 17

and the script is inside of the water

water is a block not the terrain material water!

---shortcuts
wait(math.random(0.1, 1))
local decrease_per_drain = Vector3.new(0, 1, 0)
local gallons_per_stud = 1900
local gallons_value = script.Parent.gallons_of_water.Value
local drains = script.Parent.Parent.drains:GetChildren()
local drains_open_value = script.Parent.Parent.drains.drains_open.Value
local water = script.Parent
local water_level = water.Size

---calculate gallons
wait(math.random(0.1, 1))
gallons_value = water.Size.Y * gallons_per_stud

---repeat until water level is 1
wait(math.random(0.1, 1))
while water_level <= Vector3.new(0, 1, 0) do
	---are any drains open?
	wait(math.random(0.1, 1))
	if drains_open_value == 1 then
		---lower the gallons value
		wait(math.random(0.4, 4))
		gallons_value = gallons_value - gallons_per_stud
		
		---lower the size of water
		game.Workspace.tub_of_water.hot_water.Size = game.Workspace.tub_of_water.hot_water.Size - Vector3.new(0,1,0)
		print("slow decrease")
	end
	if drains_open_value == 2 then
		---lower the gallons value
		wait(math.random(0.3, 3))
		gallons_value = gallons_value - gallons_per_stud

		---lower the size of water
		game.Workspace.tub_of_water.hot_water.Size = game.Workspace.tub_of_water.hot_water.Size - Vector3.new(0,1,0)
		print("slowish decrease")
	end
	if drains_open_value == 3 then
		---lower the gallons value
		wait(math.random(0.2, 2))
		gallons_value = gallons_value - gallons_per_stud

		---lower the size of water
		game.Workspace.tub_of_water.hot_water.Size = game.Workspace.tub_of_water.hot_water.Size - Vector3.new(0,1,0)
		print("fastish decrease")
	end
	if drains_open_value == 4 then
		---lower the gallons value
		wait(math.random(0.1, 1))
		gallons_value = gallons_value - gallons_per_stud

		---lower the size of water
		game.Workspace.tub_of_water.hot_water.Size = game.Workspace.tub_of_water.hot_water.Size - Vector3.new(0,1,0)
		print("fast decrease")
	end
end
Anonymous