Septic tank and cesspool together are a possibility. Septic tank is not used as a septic tank, but as a pumping chamber to pump uphill to the cesspool. The pump is in the septic tank, and if you have the tank emptied, you will see the pump. Another possibility is that you may have a septic tank with a leeching pit, which may resemble a cesspool, but is not. In that case, you will have a pumping chamber, (a smaller tank) between your septic tank and your leeching pit, which pumps the grey water up hill to the leeching pit. Your pump will be located in this chamber. Pumps are only used where the waste has to be pumped up hill, or over a great distance, except in case of some of the newer alternative systems which use pumps and airators.