A flooded basement. Damp walls that keep returning. Water pooling around the property after heavy rain.
As an installer, you can help customers take a more proactive approach to these issues. A permanent drainage solution can move water away before it causes damage – helping protect the property from repeated flooding, damp walls and long-term structural issues.
Permanent drainage systems protect homes against damage caused by groundwater, heavy rainfall and basement flooding. Installers use drainage pump systems within foundation drainage, perimeter drainage, drainage wells and surface drainage systems when gravity alone cannot move the collected water to an approved outlet.
Three steps to selecting a permanent drainage solution:
Introducing permanent drainage systems
Heavy rainfall, rising groundwater and hard, impermeable surfaces can leave water with no effective route away from a home. If it collects around foundations, basements or paved areas, and gravity alone can’t move it away, the result may be dampness, erosion, flooding and structural damage.
A correctly designed permanent drainage installation manages the water before it becomes an emergency. As an installer, you can deliver reliable, long-term protection – while reducing service callbacks – by preventing basement flooding with drainage systems and pumps.
So, how do you choose the most suitable drainage solutions for homes affected by groundwater and other kinds of wastewater? And to start with, how do we know when a permanent drainage system is needed?
Your selection process starts with identifying the application. Find out where the water comes from, what it may contain and where it can be discharged. Establish whether gravity can move it safely away – if not, an appropriate pump-driven solution is required.
Let’s look at each step in turn.
Start with the water and the application
Correctly identifying the water source is critical. By doing so, you’ll avoid incorrect pump selection, future service callbacks and unnecessary repeat visits.
Residential installations handle three broad types of water:
Distinguishing between them is essential because the solids, system design and pump requirements differ.
Common residential applications include foundation drainage for homes, house perimeter drainage, basement drainage systems and storm water drainage systems. Each requires a different approach depending on the source of the water, site conditions and discharge requirements.
When does a permanent drainage system need a pump?
Ask these straightforward diagnostic questions to determine when a permanent drainage system needs a pump:
Can gravity carry the water reliably to the approved outlet?
- If no, a pump is required.
Is the house, basement or collection point below the discharge level?
- If yes, a pump is required to lift the water.
Is groundwater building up pressure around the foundations?
- If yes, a pump is needed to actively remove water from the soil
Is flooding or water pooling recurring?
- If yes, a pump is needed to take the water away.
How far away is the property from the main sewer or discharge point?
- It depends on gravity. A pump is needed to transport the water over longer distances through a pressure pipe in cases where gravity drainage is impractical.
Quick pump selection checklist
☑ Identify the water source: groundwater, surface water or sewage.
☑ Determine types of solids and fibres in the water.
☑ Calculate the required flow and total head.
☑ Confirm pipe and pit requirements.
☑ Use the domestic wastewater sizing tool to confirm the final model.
Avoid these common selection mistakes
Starting with a familiar pump model before confirming the water type and application.
Treating maximum solids size as the only selection criterion.
Ignoring the actual duty point, pipework losses or discharge conditions.
Using a pit that restricts pump operation, usable volume or service access.
Overlooking backflow protection, alarms, redundancy or local discharge rules.
Assuming that a permanent installation guarantees protection in every extreme event.
Foundation, perimeter and basement drainage
⚠️ Problem: Basement flooding after rainfall or damp walls in basement
✅ Solution: Ground drainage system consisting of perimeter drainage, drainage well, automatic drainage pump
Basement drainage solutions for homes or ground drainage systems are used where groundwater may accumulate around a foundation or basement.
A common approach on how to install perimeter drainage is to use a French drain, consisting of perforated pipes often installed in a gravel-filled trench around the building, to collect moisture from the soil and guide it towards a drainage well or collection pit at the lowest point of the system.
This reduces the build-up of hydrostatic pressure against underground walls.
Where the water cannot reach a storm drain, soakaway or other approved outlet by gravity, the pit needs an automatically controlled submersible drainage pump.
To select the right pump for a basement flooding solution, begin by checking the expected solids size, duty point, pit dimensions and discharge conditions. Compact single-stage submersible pumps are sufficient for handling drainage water and smaller solids.
Grundfos UNILIFT CC and UNILIFT KP are compact options for lighter-duty installations, while UNILIFT AP12 is intended for heavier-duty drainage and handles particles up to 12 mm.
The final model selection must always be confirmed by sizing.
Surface drainage around the property
⚠️ Problem: Water pooling on driveways, water collecting near foundations or overflow during heavy rainfall
✅ Solution: Surface drainage solution consisting of rainwater and runoff collection, drainage well, automatic drainage pump
Surface drainage manages rainwater and runoff collected through gutters, downpipes, channel drains and smaller drainage points.
The water is directed towards a pit, then discharged to a storm drain, soakaway or another approved outlet. A non-return valve may be needed to prevent water flowing back into the pit.
Compared with groundwater, surface water may carry larger solids and fibres. Select a submersible wastewater pump with free passage suited to the actual water content as well as the required flow and head. Stainless-steel pumps can offer increased durability in demanding environments.
Pumps like Grundfos UNILIFT AP35 and AP35B handle particles up to 35 mm, while UNILIFT AP50 handles particles up to 50 mm. AP35B also supports auto-coupling installations.
Correctly matching inflow, solids handling and discharge conditions will help prevent recurring flooding complaints and repeat service visits. Note that where inflow is high or operational redundancy is required, a twin-pump arrangement may be appropriate.
Sewage pumping below the sewer line
⚠️ Problem: Basement bathroom below sewer line, home located below main sewer or long-distance transport to sewer
✅ Solution: Sewage pumping system consisting of drainage well including non-return valve, automatic drainage pump
If a basement bathroom is installed, or the home itself is below or far from the main sewer, a sewage pumping system is needed.
Wastewater containing toilet discharge must be collected in a sealed, odour-proof sewage pit and pumped through a pressure pipe to the appropriate public sewer or treatment system.
Backflow prevention – by installing a non-return valve in the pit – is necessary. It’s also critical to establish the local regulations that determine the final system design.
The pump must be approved for sewage and able to manage the expected solids and fibres.
Grundfos UNILIFT AP50B handles particles up to 50 mm and is optimised for sewage applications. For fibre handling or transport over extended distances, UNILIFT APG uses a professional grinder system and provides higher head.
Confirm the final solution through sizing and applying any relevant local requirements.
One principle connects every pump-driven system
The discharge route, pit arrangement, controls and backflow protection must suit the application and comply with local requirements.
How to choose a drainage pump
It’s important to make the right selection each time – never select a pump simply because the same model was used on a previous installation.
Whether you’re choosing a solution for groundwater, surface water or sewage, effective drainage pump selection for residential drainage systems starts with the application rather than the product.
Solids handling helps identify the relevant pump family, but it doesn’t determine the final selection.
Required flow and head, pipe length and diameter, pit volume, start and stop levels, inflow pattern, discharge conditions and access possibilities for service all affect the final choice.
Use an application selection guide for initial orientation, then size the pump against the actual duty point.
Quick installer selection guide
Installer checklist before selecting a pump:
☑ Identify the water source: groundwater, surface water or sewage.
☑ Confirm the possible solids and fibres in the water and their potential sizes.
☑ Find the approved discharge point and check local requirements.
☑ Establish why gravity drainage is insufficient.
☑ Calculate the required flow and total head.
☑ Check pipe length, diameter, fittings and non-return valve requirements.
☑ Confirm pit dimensions, usable volume and start/stop levels.
☑ Assess power supply, controls, alarms and any need for redundancy.
☑ Allow safe access for installation, inspection and maintenance.
☑ Use the domestic wastewater sizing tool to confirm the final model.
Key definitions
Foundation drainage: A system that collects and moves groundwater away from a building’s foundations.
Perimeter drainage: A drainage system installed around the outside of a building, usually using perforated pipes.
Drainage well: A pit or chamber that receives collected water and may house an automatic drainage pump.
Groundwater drainage: The controlled collection and removal of water from the soil around or beneath a structure.
Drainage pump: A pump used to move collected drainage water when gravity cannot reach the approved outlet.
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