We discussed your situation personally so I will summarize the discussion. Drainage pits should not be full of water. In theory they sould completely drain each day before the next day's new water is added. This does not however generally happen. The best way to treat the pits to try to ensure the best long term results, is the pump the pits, agitate the bottom using water from the pumper or perhaps a pole or pressure washer, to help break up the anaerobic crust, and then put the Septic-Scrub into the almost dry pits. If Septic-Scrub is added to full pits, there may be results but there is a higher risk that the results will be short lived. Once pits have been treated, they will fill back up again. In order to reduce the ongoing maintenance costs, Septic-Scrub should be added when the pits are about 30-40% full. This helps introduce a high concentration of product before the system is completely clogged. Probably only two bottle per pit should be needed for this treatment. There is no way to predict how often this treatment will be needed as this is a function of each system. If you have any questions, please do not hesitate to call.