The drainage pumps used in buildings include submersible sewage pumps, underwater drainage pumps, vertical sewage pumps, and horizontal sewage pumps. Due to the small size of the building and the low drainage volume, submersible sewage pumps and submersible sewage pumps can be preferred for drainage. Submersible sewage pumps are generally used in important places; Vertical and horizontal sewage pumps require seismic isolation foundations, self-priming suction, and occupy a certain amount of space, so they are less commonly used in buildings.

The flow rate of the drainage pump should be selected according to the design second flow rate of domestic drainage; When there is a drainage adjustment, the maximum hourly flow rate of domestic drainage can be selected. The flow rate of the drainage pump in the fire elevator water collection tank shall not be less than 10L/s. The head of the drainage pump is calculated and determined based on the lifting height and pipeline loss, and then a certain amount of free head is added. The free head should be 0.02-0.03MPa. The flow velocity of the suction and outlet pipes of the drainage pump should not be less than 0.7m/s and should not exceed 2.0m/s. Each domestic drainage collection tank in public buildings should be equipped with a backup pump as a unit, which should be operated interactively during normal times. If there are two or more drainage pumps for flushing the ground in the basement, equipment room, and garage, the use of pumps is not necessary. When the collection tank cannot be equipped with an accident drainage pipe, the water pump should have uninterrupted power supply; When the drainage inlet pipe can be closed, uninterrupted power supply is not required, but an alarm device should be installed. When lifting sewage and wastewater with large impurities, the outlet pipes of submersible sewage pumps in different collection tanks should not be merged and discharged; When lifting general wastewater, the discharge pipes of submersible sewage pumps from different collection tanks can be combined and discharged according to the actual situation. When two or more water pumps share the same outlet pipe, valves and check valves should be installed on the outlet pipe of each water pump. When a single water pump may cause backflow during drainage, a check valve should be installed. It is not allowed to merge the pressure drainage valve with the gravity drainage pipe inside the building for discharge. When the submersible sewage pump is lifted with large debris, it is recommended to have a crushing device; When lifting wastewater containing a high amount of fiber, it is advisable to use a large channel submersible sewage pump. When the power of the submersible sewage pump motor is greater than or equal to 7.5kW or the outlet pipe diameter is greater than or equal to DN100, a fixed self coupling device for the water pump can be used; When the power of the submersible sewage pump motor is less than 7.5kW or the outlet pipe diameter is less than DN100, a flexible hose mobile installation can be installed. When using submersible sewage pumps for drainage in sewage collection tanks, a fixed self coupling device should be installed to facilitate pump maintenance. The drainage pump should be able to start and stop automatically and manually on site. Multiple water pumps can operate alternately in parallel or in sections.