Pumping Systems

Hydraulic pumping systems move water where gravity and mains pressure cannot: domestic water booster sets that raise pressure to upper floors, stormwater sump pumps that keep basements and car parks dry, sewage ejectors that lift waste from below the sewer, lift pit pumps, and the pits, controls, alarms and rising mains that go with them. Fire pumps have their own page.

Many sump and sewage pumps have no backup power, so they stop in the same storm that knocks out the mains supply and floods the basement. In basement car parks and plant rooms, a failed sump pump can put the main switchboard, lifts and fire pumps under water.

What shortens life:

• Silt, debris and rags drawn into pumps.
• Hydrogen sulphide in sewage pits corroding concrete, steel and electrical equipment.
• Short cycling from failed pressure vessels or poor level settings.
• No maintenance because pumps are out of sight.

Level control failure

Float switches tangle, stick or foul with grease and debris; level sensors drift. The pump either does not start, letting the pit overflow, or runs dry and burns out. A high-level alarm is the last line of defence, and it is often not monitored.

Blockage and ragging

Sewage pumps block with wet wipes, rags and fats; stormwater pumps block with silt, leaves and litter washed down ramps. Pumps trip on overload and the pit fills.

Loss of power

Sump and sewage pumps without generator or battery backup fail in power outages, which often coincide with storms. Basements then flood exactly when the drainage is most needed.

Booster set failures

Pressure vessels lose their charge and diaphragms fail, so pumps start and stop constantly; drives fail; one pump fails and the others cannot meet peak demand; controls lose their settings. Upper floors get low pressure or none.

Hydrogen sulphide

Sewage in pits produces hydrogen sulphide, which corrodes concrete and metal and is lethal in confined spaces. Pits need ventilation, and entering them is confined space work.

Check valve failure

Check valves on rising mains stick open, letting water run back into the pit, so pumps cycle continuously; or stick closed, so pumps run against a closed valve.

Capacity shortfall

Pits and pumps sized for the original catchment are overwhelmed when ramps, courtyards or new connections are added, or when rainfall intensities increase.

On site

• Water marks and silt lines on basement walls; corrosion at the base of switchboards and equipment.
• Pit lids: condition, odour, ventilation.
• Pumps: duty and standby both present; run hours; noise.
• Alarm panels: high-level alarm, monitoring connection.
• Booster set: number of pumps running, pressure gauges, vessel condition.
• Low pressure complaints on upper floors.

In the records

• Pump maintenance and pit cleaning records.
• Flood incident history.
• Alarm monitoring arrangements.
• Backup power arrangements.
• Pump and pit design capacities.

• Silt, leaves and litter on car park ramps and grates feeding the sump, and the condition of silt traps.
• Odour around sewage pits and corrosion of fittings near them, signs of hydrogen sulphide.

Findings are graded by what they demand: safety (can hurt someone now), failure (failed and damaging the building), condition (distress present and progressing), lifecycle (renewal due on age and exposure), deadline (a regulator or ordinance sets the date), check (investigate before sizing works) and nil (cosmetic or stable).

A hydraulic engineer or pump contractor; confined space procedures for pit entry.

• Inventory of every pumping system, pit, pump, control and alarm.
• Function test: start and stop levels, duty and standby changeover, high-level alarm and its monitoring.
• Pump condition: insulation resistance of motors, impeller wear, run hours.
• Pit inspection: silt, grease, concrete condition, H2S levels, ventilation.
• Booster testing: pressures at top floors at peak demand, vessel charge, drive faults.
• Capacity review: catchment, rainfall intensity and pump capacity.
• Power review: backup supply for critical pumps.

The report should list each system with its condition, flood risk, alarm and power arrangements, and works needed.

• Drawdown test: measure how quickly each pump empties the pit against its rated capacity, which shows wear and blockage that a simple start test misses.

• Controls: replace floats with reliable level sensors; set alarms to a monitored system.
• Backup power: generator connection or battery backup for critical sumps.
• Pump replacement with vortex or cutter pumps for sewage.
• Pit cleaning on a schedule; silt traps on ramps.
• Pressure vessel replacement and recharge.
• Check valve replacement.
• Pit refurbishment: H2S-resistant linings, ventilation, lockable lids.
• Capacity upgrade: larger pumps, additional pumps, bigger pits.
• Flood protection of switchrooms below ground.

• Duty and standby alternation so both pumps share run hours and a failed standby is found before it is needed.
• Education and screening for sewage systems: signage about wipes and fats, and macerators or screens where ragging recurs.
• Variable speed booster sets replacing fixed-speed pumps, with correctly sized pressure vessels, to cut energy and pressure fluctuation.

Maintenance and pit cleaning recur. Pump replacement is per pump. Controls and alarms per system. Backup power per system or as part of a generator project. Pit refurbishment and capacity upgrades are lump sums. Booster set replacement is a lump sum with temporary supply.

Replacement is lifecycle; repairs and cleaning are repairs and maintenance; flood protection works and alarms may be risk-driven or code compliance.

Temporary pumping during replacement is a separate line where the pit cannot be left unattended.

• Australia. AS/NZS 3500.1 covers water boosters, AS/NZS 3500.2 sanitary pumps and AS/NZS 3500.3 stormwater pumps; confined space entry follows AS 2865 and the work health and safety regulations.
• United Kingdom. Approved Document H covers drainage; BS EN 12056-4 covers wastewater lifting plants; the Confined Spaces Regulations 1997 govern pit entry.
• United States. The International and Uniform Plumbing Codes cover sumps, ejectors and booster pumps; OSHA 29 CFR 1910.146 governs permit-required confined spaces.

In all three jurisdictions, sewage pumping into the public sewer may also be subject to the utility's connection conditions, and flooding of basements from failed pumps is commonly excluded from or limited under insurance where maintenance cannot be shown. Strata and leasehold buildings usually treat sump and booster systems as common property, maintained by the owners corporation or landlord.

• Pump maintenance and pit cleaning records.
• Flood incident history.
• Alarm monitoring arrangements.
• Backup power arrangements.
• Pump and pit design data.
• Upper floor pressure complaints.

• Insurance claims for basement flooding.
• Drawdown or capacity test results.
• Hydraulic drawings showing pits, catchments and rising mains.

• Pressure vessel charge records and booster set service reports.