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Water where it shouldn’t be creates serious problems for property owners. Basements flood when water can't reach the main sewer line, stormwater pools in carparks, and low-lying areas turn into swamps. Drainage pumps, including sump pumps, solve these issues by moving excess water away from your property.
Understanding how drainage pumps work helps you choose the right system and maintain it properly. In this blog post titled "How Does a Drainage Pump Work," we'll explore the basics of these essential water management tools so you can make informed decisions about your property's drainage needs.
Drain pumps move water from one place to another using mechanical force. They overcome gravity and distance to redirect water away from areas where it causes damage.
The basic principle is simple. Water collects in a pit or sump basin, which is where a sump pump is installed. When the water level rises to a certain point, the pump activates. The sump pump's job is to draw water in through an inlet, push it through the pump body, and discharge it through an outlet pipe to a safe drainage point.
Every drainage pump system has several essential parts working together:
The pump motor provides the power. It turns electrical energy into mechanical energy that moves water. Motors are rated by horsepower, with stronger motors handling larger volumes and higher discharge heights.
The impeller is a rotating disc with curved blades. As it spins, it creates a low-pressure area that draws water in. The spinning action then flings water outward with force, pushing it into the discharge pipe.
The float switch acts as the pump’s automatic control. It rises with the water level. When it reaches a set height, it triggers the pump to start. As the water level drops,the float falls and shuts the pump off.
The discharge pipe carries water away from the pump. It needs to be sized correctly for the pump’s output and positioned to drain water to a safe location.
A check valve prevents backflow. After the pump stops, this one-way valve keeps pumped water from flowing back into the sump. This saves energy and prevents constant cycling.
These components work together in various pump configurations. Submersible pumps house all these parts in a sealed, waterproof casing, while pedestal pumps keep the motor assembly above water level.
Different applications need different pump types. The main categories are:
Most sump pumps are submersible drainage pumps that sit underwater in the sump pit. They're sealed units designed to operate while submerged. These pumps are quieter and more efficient than other types. They’re common in basement applications and stormwater systems.
Pedestal sump pumps mount above the water on a column or stand. Only the intake sits in the water. These are easier to service because the motor stays dry. However, they’re noisier and take up more space.
Sump pumps specifically handle groundwater that seeps into basements or crawl spaces, moving it to the main sewer line or drainage system. They prevent flooding and moisture damage in below-ground areas.
Stormwater drain pumps move rainwater from collection points like carpark sumps or low areas. These often handle larger volumes during heavy rain events.
Understanding the complete pumping cycle shows how these systems protect your property:
Drainage pumps differ from other pump types in important ways. They’re built to handle dirty water containing debris, sand, and small solids.
The impeller design allows passage of solid particles. Submersible pumps and other drain pumps can handle solids up to 50mm in diameter. This prevents constant clogging from dirt and debris.
They're also designed for intermittent operation, efficiently removing excess water as needed. Unlike pumps that run constantly, sump pumps and other drainage pumps cycle on and off based on water levels. This requires durable motors and switches that handle frequent starting and stopping.
A clogged drain pump shows several warning signs. Catching these early prevents flooding and expensive damage.
Strange sounds often indicate blockages. A grinding or rattling noise suggests debris caught in the impeller. The pump struggles to spin freely, creating these harsh sounds.
A humming sound without water movement means the motor runs but the impeller can’t turn. Something is jamming the mechanism.
Healthy drain pumps run with a steady whirring sound. Any deviation from this normal noise deserves investigation.
If water levels drop slower than usual, the pump might be partially blocked. Reduced flow means the impeller can’t move its full capacity.
Watch how long the pump runs during each cycle. Longer run times with less water removed point to blockage or wear.
The sump might also empty incompletely, indicating your sump pump needs attention. A clogged pump leaves standing water that never fully drains.
When pumps turn on and off rapidly, something is wrong. This “short cycling” happens when the pump runs but doesn’t move enough water to drop the float switch.
Partial blockages reduce pumping efficiency. The water level falls slightly, then rises again quickly, triggering another cycle.
This constant starting and stopping wears out motors and wastes electricity. It’s also a clear sign that maintenance is needed.
The most obvious sign is water that won’t drain away. If your sump pit fills higher than normal, or water backs up into areas that should be dry, the pump isn’t working properly.
Check the sump pit regularly during wet weather. Rising water despite a running pump indicates serious blockage or pump failure.
Sometimes you can see the problem. Leaves, plastic bags, gravel, or other debris might be visible in the sump pit or around the pump inlet.
The discharge pipe opening might show reduced water flow or unusual materials being expelled. These are signs that blockages exist somewhere in the system.
Understanding common causes helps prevent future blockages:
Sediment and silt build up over time. Fine particles settle in the sump pit and can get drawn into the sump pump. Regular cleaning prevents this accumulation.
Leaves and organic matter commonly block outdoor drainage pumps. Autumn creates particular problems as falling leaves enter drainage systems.
Construction debris like concrete chunks, gravel, or plastic wrapping can jam impellers. Always clear work areas and protect drainage points during renovations.
String-like materials such as tree roots, fabric strips, or long grass wrap around impellers. These create tight blockages that stop pumps completely.
Drain pumps are not designed to run continuously. They’re built for intermittent operation, turning on when needed and shutting off once water is removed.
If your drain pump runs non-stop, you have a serious problem that needs immediate attention.
Pump motors generate heat during operation. They’re designed to cool during off periods. Continuous running prevents this cooling, causing motors to overheat and fail.
The impeller and seals wear rapidly under constant use. Parts designed for intermittent duty deteriorate quickly when forced to run non-stop.
Electricity costs soar with continuous operation. A pump running 24 hours daily uses far more power than one cycling normally for a few hours.
Several problems cause pumps to run without stopping:
A stuck float switch won’t release to turn the pump off. The switch might be tangled in its cable, jammed against the pit wall, or mechanically failed.
The sump pump is undersized for the water inflow. If water enters faster than the pump can remove it, the system never catches up. The float stays elevated and the pump runs constantly trying to keep pace.
A faulty check valve allows water to flow back into the sump. The pump drains the pit, shuts off, then refills as water returns through the failed valve. The cycle repeats endlessly.
Discharge pipe blockages restrict water flow. The pump runs but can’t move enough water to lower the sump level significantly.
An exceptionally high water table during wet periods creates constant inflow. Groundwater seeps in as fast as it’s pumped out.
If your drain pump won’t stop running, take action quickly:
Check the float switch first. Make sure it moves freely and isn’t caught on anything. Test if manually lowering the float stops the pump.
Inspect the discharge pipe. Look for kinks, blockages, or frozen sections in cold weather. Verify water is actually flowing out the end.
During extreme weather or flooding, continuous running might be unavoidable short-term. However, the pump will fail eventually. Consider adding a backup pump or upgrading to a larger capacity system.
Regular maintenance prevents most drainage pump issues. Sump pumps benefit from professional servicing every 6-12 months to keep systems running reliably.
Clean the sump pit annually to handle excess water efficiently. Remove accumulated sediment and debris before it reaches the pump.
Test your pump before wet seasons to ensure proper drainage. Run it through several cycles to verify proper operation. Better to find problems during dry weather than during a storm.
Install screens or filters at drainage entry points. These catch leaves and debris before they enter the sump pit.
Consider a backup sump pump for critical applications. Basements prone to flooding benefit from redundant systems. If the primary pump fails, the backup takes over.
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