Pumping requirements for drainage water, greywater, rainwater and blackwater

For the drainage of clean or grey water, removal of effluent including effluent containing fibres, or for the handling of sewage including toilet discharge, many issues need to be considered before making your investment.
In this module, we’re going to take a closer look at some of these issues.
For example, do you have a particular problem that needs to be resolved, such as pumping rainwater from a flooded basement, or regular problems with flooding caused by backflow from the sewer mains? Is your requirement for a permanent or portable pumping solution? Or perhaps you should consider your pumping requirements from a more general perspective:
• Do you know the nature of your drainage water, greywater, rainwater and blackwater?
• Does the effluent or sewage contain large particles and fibres?
• Do you know the running requirements for the pumping solution?
These issues are important, as they could affect, for example, material choice and construction.
Firstly, it is necessary to understand the nature of your drainage water, greywater, rainwater or effluent, and blackwater:

Drainage water is raw water and collected groundwater and greywater is untreated wastewater from wash basins, showers, floor drains and appliances containing solids no larger than 12 mm from households and small industry;

Greywater and rainwater (effluent) is dirty water and untreated wastewater (excluding toilet discharge), containing fibres and solids no larger than 35 mm from dewatering systems, domestic and commercial buildings and surroundings;

Blackwater is defined as dirty water and untreated wastewater including toilet discharge, containing fibres and solids no larger than 50 mm from dewatering systems and domestic wastewater systems. For pumping untreated wastewater, you could also consider using a grinder pump;

Sewage is untreated wastewater and raw sewage containing fibres, textiles and other solids, including toilet discharge from domestic sewage systems, farms and industry connected to the municipal mains system. To avoid clogging, pumps allowing free passage of solids of minimum 80 mm are recommended in municipal applications.

At Grundfos, our experience says that a semi-open impeller is fine for free passage up to 12 mm. Beyond that, we recommend a Vortex impeller, where you get free passages of 35 or 50 mm, or even more when we get to pumps with more than 2 kW of power.

Secondly, you need to understand your installation requirements, and ensure that they match the drainage water, greywater or blackwater requirements:

Applications for mobile use
Drainage pumps and small effluent pumps are used for portable applications. These include emergencies, for example flooding events inside and outside buildings, and to pump (waste)water out of tanks, ponds or swimming pools;

Applications for stationary (fixed) installations
Drainage pumps and small effluent pumps are used for fixed, stationary installations:
• On- and under-floor tanks (lifting stations) or simple concrete pump sumps inside the building,
• Pumping stations and small domestic treatment plants outside the building,
• Industrial and commercial use."
For applications where pumped media includes brackish water in ports, sea water, or saltwater from water softeners, higher graded material on the motor and shaft is required, to reduce corrosion risk.

That was a brief introduction to the installation requirements for a permanent or portable pumping solution for pumping drainage water, greywater, rainwater, and blackwater.

If you are interested in finding out how the Grundfos UNILIFT range of submersible drainage pumps meets the requirements for the applications and installations described above, please see the second module “Grundfos UNILIFT range of submersible drainage pumps” in this ECADEMY course about Wastewater handling with the UNILIFT range.