How many Litres are in a community pool?

You must give more information: what is the shape of the pool, and in most cases, additional measurements are required. For example, for a rectangular pool, you will need length, width, and depth.

You need to specify the three dimensions of the pool; assuming that the pool is rectangular and of constant depth, you multiply the height,width and depth (in metres) to calculate the volume of the...

It depends on what pool you're talking about.

You need to know the height of the pool to answer. Liquid is measured in volume, 3 dimensions (m3)

That would depend what shape and how deep the pool is. If it is a round pool, 18 feet across and 4 feet deep, you would have 1000 cubic feet (pi R squared D), which is 28,300 liters.