What is a Pump

A pump is a mechanical device used to move liquids from one location to another, particularly when gravity alone cannot provide the necessary flow. In drainage and wastewater systems, pumps are essential for transporting both surface water (such as rainwater) and foul water (wastewater from toilets, sinks and appliances) when the terrain, building layout or infrastructure does not allow for a natural downward slope.

Pumps are widely used in domestic, commercial, and municipal settings and are an integral part of modern drainage engineering. They help ensure that water and waste are efficiently removed from properties, preventing flooding, backflow, and environmental contamination.

When pumps are needed in drainage

Gravity drainage relies on pipes laid at a constant gradient to carry water away. However, in many real-world scenarios, gravity alone is not sufficient. Pumps are required when:

  • The property is located below the level of the nearest sewer or drain

  • Wastewater must be lifted from a basement, cellar or low-level toilet

  • The site is flat and cannot provide adequate slope for flow

  • Discharge needs to travel over a long horizontal distance before reaching an outlet

  • Flooding or pooling of surface water must be mitigated

Pumping systems provide the pressure and force needed to move water vertically or across level ground.

Types of pumps used in drainage systems

Several types of pumps are employed, depending on the application, volume, and type of water being handled.

Submersible pumps

These are fully sealed units designed to operate while submerged in water. They are commonly used in:

  • Sump basins in basements

  • Sewage lifting stations

  • Flooded areas or stormwater attenuation tanks

Submersible pumps are compact, reliable and operate quietly beneath the surface.

Sewage pumps (foul water pumps)

These are designed to handle wastewater containing solids. They are typically used to move sewage from a property to a higher-level sewer or treatment plant. Key features include:

  • Solids handling impellers

  • Macerating blades (in some models)

  • Durable construction to resist corrosion and clogging

Surface-mounted pumps

These pumps are installed above the water source and use suction to draw water into the system. They are more common in agricultural or temporary dewatering applications and are less suitable for deep or heavily contaminated water.

Twin or duty-standby systems

In larger installations, dual-pump configurations are used for redundancy. One pump operates under normal conditions, and the second activates if the first fails or if demand increases. This is common in commercial settings and critical infrastructure.

Key components of a pumping station

A pumping station, also called a pump chamber or wet well, typically includes:

  • A collection chamber to hold incoming water or wastewater

  • One or more pumps to lift and discharge the contents

  • Non-return valves to prevent backflow

  • Control panels and level sensors to automate operation

  • Alarm systems to alert users in case of failure

In domestic applications, compact packaged pump stations are available as plug-and-play units with all necessary components pre-installed.

Applications of pumps in drainage and wastewater management

Pumps are used across many scenarios, including:

  • Basement and cellar drainage
    Lifting greywater or sewage from below-ground facilities to ground-level sewers

  • Flood mitigation
    Pumping surface water from low-lying areas or flood-prone developments

  • Package treatment plants
    Moving effluent from a septic tank or treatment plant to a soakaway or watercourse

  • Rainwater harvesting systems
    Circulating water from storage tanks to irrigation or toilet flushing systems

  • Construction and civil engineering
    Dewatering excavations and tunnels

  • Remote or off-grid locations
    Moving waste to tankers or off-site treatment systems

Each application requires a careful assessment of flow rate, head (vertical lift), and the nature of the water being pumped.

Maintenance and reliability

To function effectively, pumps must be properly installed, maintained and regularly tested. Common maintenance tasks include:

  • Inspecting and cleaning the pump and chamber

  • Checking for blockages or wear to impellers

  • Testing float switches or level sensors

  • Verifying power supply and alarm functions

  • Replacing worn seals, bearings or electrical components

Failure of a pump system can lead to flooding, backflow or overflows of untreated sewage, making preventative maintenance essential.

Legal and design considerations

In the UK, pumped drainage systems must comply with Building Regulations, including:

  • Document H (Drainage and Waste Disposal)

  • WRAS (Water Regulations Advisory Scheme) standards for water fittings

  • Manufacturer guidelines on flow rates and head pressure

Planning permission or environmental permits may be required if discharge is directed to a watercourse or ground. Additionally, in commercial or multi-unit properties, pumps must be sized to cope with peak loads and provide backup capability.

Limitations and challenges

While pumps offer many benefits, there are some limitations:

  • Energy use
    Pumps require a continuous power supply, increasing operational costs and dependency on electricity

  • Mechanical failure
    Moving parts are subject to wear, and breakdowns can cause serious disruption

  • Sensitivity to misuse
    Non-flushable items, fats and foreign objects can clog pumps and require professional removal

  • Installation constraints
    Proper siting, ventilation and access must be considered during design

Despite these challenges, modern pumps are engineered for durability and often come with advanced control features, such as telemetry and smart sensors.

Conclusion

A pump is a vital tool in any drainage or wastewater system where gravity cannot provide adequate flow. It allows for the controlled and efficient movement of foul and surface water in a wide range of settings, from individual homes to large commercial installations.

Whether lifting sewage from a basement toilet, managing stormwater in a flat development or discharging effluent from a treatment plant, pumps provide flexibility, reliability and protection against water-related risks. When properly selected, installed and maintained, a pump system ensures continuity of service, environmental compliance and the safe operation of drainage infrastructure.