No. Actually, in 99% of septic tanks, adding bacteria is not necessary since bacteria occurs naturally in properly working and maintained systems. There are some exceptions, mainly due to the overuse of anti-bacterial soaps, disinfectants, laundry detergents, bleach and sanitizers. These products kill bacteria in the septic system, so we suggest limiting their use. We also suggest using phosphorus free laundry detergent. Bacterial additives are expensive and even when their addition may be helpful, it is important to be aware that adding bacteria does not mean the system can go indefinitely without being pumped out. Bacteria will not remove sludge and lint particles which will clog your drain field, therefore the tank must be pumped out periodically to prevent system failure. An honest service provider will advise you of any need for bacterial additives in your system. Bacterial additives do not have guarantees or warranties that cover replacement of your system if the product does not do what it promises and your system fails. You may be able to get the money you paid for their product returned, but that is of little consolation if you have to replace your septic system, since a new system can cost upwards of $17,000.00.