How to match a submersible pump to clear water, greywater, sewage or site water: impeller types, sump and lifting station design, level controls, alarms, duty and standby pumps, and an RFQ checklist.
Pick a sump, drainage or sewage pump by what is in the water. Clear water drainage pumps suit basement sumps and tank drains; greywater and effluent need a vortex or open impeller; raw sewage needs a sewage pump with a large free passage, a self-cleaning impeller or a cutter. Then size it for the inflow and the lift, and fit level controls, a check valve, an alarm and a standby pump. ListGCC's submersible pump suppliers in the UAE stock all three.
This guide is for MEP contractors, facility managers, developers and site engineers dealing with basement drainage, sewage lifting and pumped drainage. Our guide to water pumps in the UAE and Saudi Arabia covers construction dewatering, saline water materials and the Dubai rules on dewatering works; here we go into the building and site side: matching pump to liquid, impeller types, sump and lifting station design, controls and redundancy.
Makers organise their submersible ranges by the liquid. Pedrollo's sewage and drainage catalogue, for example, describes its series as drainage pumps for clear water, drainage pumps for greywater (including vortex versions of its clear water models), pumps for slightly loaded sewage, and sewage pumps, with separate lifting stations. Tsurumi groups its submersibles into dewatering (portable, high-head, slurry and residue dewatering, and pumps for sewage bypass), sewage and wastewater pumps in cast iron, resin, stainless steel and cast stainless, seawater pumps, and specific applications.
| Liquid | Typical source | Pump to look for | Watch for |
|---|---|---|---|
| Clear water | Basement and lift pit seepage, tank and pool drains, condensate | Clear water drainage pump with float switch | Float clearance in the pit; fine solids only |
| Greywater and lightly loaded effluent | Showers, basins, laundry, kitchen pre-treated water, rain run-off | Drainage pump with vortex or open impeller | Lint, grease and small solids |
| Raw sewage | Toilets below sewer level, basements, villas and compounds without gravity connection | Sewage pump with large free passage, self-cleaning impeller, or cutter or grinder | Rags, wipes and fibrous material; gases in the wet well |
| Sludge | Treatment plants, tanks, digesters | Wastewater pump rated for solids concentration, or a progressing cavity pump (see our pump types guide) | Solids content and abrasion |
| Sandy site water | Excavations, trenches | Dewatering pump with wear-resistant hydraulics | Sand, continuous running, cable length |
The impeller decides whether a sewage pump keeps running or blocks. The main families on the market:
Two cautions when comparing quotes. First, free passage (throughlet) size is often used as the measure of clog resistance; Flygt notes this is frequently done and publishes a white paper questioning whether it is enough on its own. Ask what the pump is designed to do with rags and wipes, not only the sphere size it passes. Second, match impeller material to the grit: Flygt recommends hardened cast iron for typical wastewater, Hard-Iron where there is sand and grit, and duplex stainless steel for highly corrosive wastewater.
Sewage adds one constraint. A lift station's wet well must not hold sewage so long that it goes septic, and gases including methane and hydrogen sulfide can build up in it. Size the working volume for pump starts but not for long retention, ventilate the well, and treat it as a hazardous confined space during maintenance.
A sump pump removes water that collects in a sump basin. Pedestal pumps keep the motor above the pit on a column; submersible pumps put a sealed motor in the water and are now the more common style. A sewage lift station does the same job for wastewater: sewage flows into a wet well, and submersible sewage pumps with close-coupled motors, mounted inside it, push it up through a pressurised force main to a higher sewer.
For villas and small buildings, packaged lifting stations combine a tank, pumps and controls. Pedrollo lists its SAR series of lift and collection stations, and Flygt lists packaged wastewater and sewage pump stations. For larger systems, browse sewage treatment plant suppliers and stormwater management system suppliers.
Site dewatering pumps work with sand, silt and continuous running. Tsurumi alone splits its dewatering range into portable, standard, high-head, slurry and residue dewatering pumps. Choose by the solids (clear seepage, sandy water or slurry), the head to the discharge point, the cable length to the site panel and whether the pump runs continuously or on level control. Large deep excavations need an engineered wellpoint or deep-well system; the main guide covers the Dubai approvals and a published Dubai example.
In Dubai, dewatering is treated as ancillary construction work under the construction works order described in the main guide; confirm with Dubai Municipality what approvals the dewatering design and its discharge route need. For building drainage and sewage connections, confirm the accepted arrangement and discharge point with the municipality and the sewerage operator in your emirate before fixing the pump room design.
Building drainage design falls under the Saudi Building Code: SBC 701, the plumbing code, covers sanitary drainage, and SBC 702 is the private sewage disposal code. Both appear in SASO's list of codes for which inspection bodies are accepted. Browse submersible pump suppliers in Saudi Arabia and wastewater treatment suppliers in Saudi Arabia.
Coastal groundwater and sewage are both hard on materials. Tsurumi offers sewage pumps in cast iron, resin, stainless steel and cast stainless steel, and titanium and seawater-resistant pumps; Flygt offers duplex stainless steel impellers for highly corrosive wastewater. Send a water or effluent analysis with the RFQ and ask for the material of every wetted part.
Flygt lists N-technology self-cleaning wastewater pumps, channel impeller pumps, the Concertor clog-free system, packaged wastewater and sewage pump stations, dewatering pumps and pump monitoring and controls.
Tsurumi makes submersible dewatering, slurry, sewage and wastewater pumps in several materials, BN cutter pumps for fibrous sewage, seawater and titanium pumps, and float switches.
Pedrollo lists clear water drainage pumps (including stainless steel RX models), greywater vortex versions, sewage pumps such as the VX and BC series, and the SAR range of lift and collection stations.
Then post your sump or sewage pump requirement on ListGCC so suppliers quote on the same liquid and duty.
More in this series: Booster Pump Sizing for Buildings, Submersible Borehole Pumps, Fire Pumps and Jockey Pumps.
A sump pump removes water that collects in a sump basin, usually clear or lightly dirty water from seepage or drainage, and only passes small solids. A sewage pump is built for wastewater containing solids and fibres, with a large free passage, a self-cleaning or channel impeller, or a cutter.
There is no single best type; makers use self-cleaning (non-clog) impellers, channel impellers, vortex impellers and cutters. Tsurumi's BN cutter pumps shred fibrous solids with a scissor action between a rotating and a stationary blade, and Flygt's N-technology impellers are designed to be self-cleaning. Free passage size alone is not a complete measure of clog resistance.
Usually through a float switch that starts the pump when water rises to a preset level and stops it when the level falls. Pressure switches and solid-state level sensors are alternatives. The float must hang free of obstructions, and a separate high water alarm should warn if the pump fails or cannot keep up.
For anything serving a building, yes. Sewage lift stations are designed with redundancy so they keep working when any one pump is out of service. Fit duty and standby pumps with automatic alternation, a high level alarm and, where the risk justifies it, backup power.
Not as a rule. Dewatering pumps are built for water carrying sand and silt, with wear-resistant hydraulics, while sewage pumps are built to pass soft solids and fibres. Some makers offer pumps specifically for sewage bypass work, such as Tsurumi's range, so ask for a pump rated for the liquid you have.
Clear water from a sump normally goes to a storm drain, a dry well or open ground away from the building, not the foul sewer; discharging it into a sanitary sewer can break plumbing codes or local rules. Sewage from below-grade toilets goes to the foul sewer through a lifting station. Confirm the connection point with the local authority before installation.
Featured image: Photo: Kemikungen, CC BY 3.0, via Wikimedia Commons
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