A tensiometer measures the force with which water is held in the soil by the soil particles. This force, referred to as soil suction, tension, or potential, indicates how tightly the water is bound in the soil, and how much energy must be exerted by plant roots to remove and use the water. The basic components of a tensiometer include a porous ceramic cup, a plastic body tube, and a vacuum gauge. The ceramic cup is placed in good hydraulic contact with the soil and allows transfer of water into and out of the tensiometer body according to the tension in the soil. The vacuum inside the tensiometer body equilibrates with the soil water tension, and the dial gauge provides a direct readout of the tension.

The Model 2725AR Jet Fill Tensiometer features the patented Jet Fill reservoir for push-button convenience and minimization of soil disturbance when servicing is required. Unique modular construction allows for easy replacement of the porous ceramic cup and dial gauge and adaptation of extensions for flexibility and variety in use. Series 0240 Insertion Tools can be used to core a hole to accept these units.