Want to know the liquid level in a tank? The difference between the density of a liquid within 1% margin? Then this is your tool: this sensor concept uses a membrane which responds to (hydraulic)pressure. Placing multiple sensors strategically enables the user to calculate the density of a liquid and as a result, the liquid level, distinct the different types of liquid and the separation faces between the two. As a side effect, this sensor also measures the temperature. This concept is tested in a live setting for one of the largest liquid bulk storage companies in the world.