Abstract: An improved agitator assembly (10) for sanitary tanks includes a drive shaft (14) extending through a tubular housing (58, 84). A slide coupling (16) is connected between the outer end of the drive shaft (14) and a drive motor. An impeller (90) is secured to the other end of the drive shaft (14) which is supported on a bearing/seal member (86) in the inner end of the shaft housing (58, 84). The adjoining surfaces of the bearing/seal member (86) and impeller base (89) are normally engaged in rotary sealing relationship by springs (44, 78) but shift apart responsive to introduction of cleaning solution into the housing (58, 84) so that the cleaning solution is discharged into the tank at the base of the impeller (90) after washing the seals (74, 86) to facilitate cleaning without manual disassembly or scrubbing.