What is a dosing tank?
While not a “kind of septic system”, a dosing tank (or pump tank) is an integral part of any pumped septic system like a mound system or flood dose system. It is a tank (built like a septic tank ) that contains one or more effluent or sewage pumps, controls, etc. Float type control switches inside tank turn the pump on and off . The pump delivers a “dose” of water to the absorption field. Dosing tanks usually require a high water alarm to notify the owner in the case of a pump failure. Electrical connection should be made outside of the dosing tank and riser in a weather proof box. Gases inside the tank are very corrosive and will quickly destroy any exposed metal.
Some septic system (i.e. mound type systems) require smaller doses of effluent while flood dose systems can accept larger doses. Dosing tanks are often required when an existing septic tank is too deep to accommodate a shallow trench repair system.
Saturated zones in a septic absorption fields promote the grow of anaerobic bacteria and a bio-mat. Bio-mats form at the soil interface. This is a normal thing in septic systems (and not all bad). However, when the biomat become substantial enough, it can slow and even stop your systems infiltration of wastewater and and cause your septic system to fail. Dosing tanks can help slow the formation of this biomat (and thus your system’s failure).
Gravel absorption trenches contain about 33% void space. This space allows your absorption trenches to store wastewater until it can be absorbed into the ground. A dosing tank can use this storage capacity to your advantage by pumping lots of water to your trenches just once a day. This allows your trenches to drain and rest in a well drained state prior to the next dose. This helps to eliminate these zones of constant saturation.