Sump pump system
A sump pump system removes water that collects in a low point of a building and lifts it to where it can drain away. In Singapore that low point is usually a sump pit in a basement, car park, waste water collection box or trench, sitting below the level of the drain or sewer outside. Because the water cannot flow out by gravity, it has to be pumped.
Waves Fluid Engineering Pte Ltd designs, supplies, installs, maintains, repairs and replaces sump pumps, their parts and accessories across Singapore. We work on everything from a single auto-float pump in a small pit to duplex systems with control panels, multiple float switches and guide rails in commercial and industrial buildings.
What does a sump pump do?
It collects water in a pit and automatically pumps it out when the level rises, protecting the basement or car park from flooding and keeping waste water moving where gravity drainage is not possible. Float switches start and stop the pump, so the system runs unattended around the clock.
Also known as: sump pit pump, drainage pump, submersible drainage pump, basement pump, car park sump pump and rainwater sump pump. All describe a pump that empties a collection pit.
Storm water sump or used water sump?
This is the first thing to establish, because the two are regulated differently in Singapore and must stay separated. Getting it wrong at design stage causes problems at submission and inspection.
Storm water
Rainwater and basement seepage
Water entering a basement or car park from rain and surface ingress. Handled as a pumped drainage system under PUB's Code of Practice on Surface Water Drainage, and discharged through the development's internal drainage, not straight into the public drain.
Used water
Waste water and sewage
Discharge from toilets, kitchens, pantries and floor traps below sewer level. Handled as a sewerage pumping installation under the Code of Practice on Sewerage and Sanitary Works, and discharged to the inspection chamber and sewer.
Types of sump pump system we install
We work with all three arrangements commonly used in Singapore, chosen on the design requirement and site conditions:
1
Sump pump with auto-float
The simplest to install. The pump starts when the rising water lifts its integral float switch to the activation height, and stops when the level drops. Used for small pits, collection boxes and trenches.
2
Two-pump (duplex) system
Two pumps with a control panel, most often used as the rainwater sump pump in basement car parks. Sized on the water inflow, pipe sizes and the level it has to be pumped up to.
3
Sump pump in an ejector pit
Installed inside an ejector pump system to clear the waste water collected in the ejector pit, using either an auto-float pump or float switches wired to the panel.
PUB requirements for basement pumped drainage
If the sump serves a basement or other underground space, the system is not just a pump in a hole. PUB's Code of Practice on Surface Water Drainage sets out design criteria that your Qualified Person has to satisfy at submission, and which a replacement or upgrade should respect:
N + 1 / N + N
Standby pump redundancy
General developments require at least N duty plus 1 standby pump, and other development types at least N duty plus N standby, where N is the number of pumps needed for the design capacity.
3 hours
Sump storage capacity
The pump sump must hold the total inflow from the whole source catchment for at least three hours, so the building is covered during a breakdown, repair or power failure.
150 mm/hr
Design ingress rate
The pumped drainage system is designed for water ingress of not less than 150 millimetres per hour from the entire source catchment area.
Generator
Backup power and controls
The system must be supported by a generator if main power fails, and must start automatically on storm water ingress with a manual override option.
Discharge point matters: a basement pumped drainage system should not discharge directly into the roadside or public drain. The outlet is taken through a swan neck connection into the development's internal drain or internal sump before it reaches the roadside drain, and the crest level requirement applies. We work to your QP's drawing on this.
For used water sumps the Code of Practice on Sewerage and Sanitary Works applies instead. It requires duty and standby pumps with reflux and isolating valves, a pump that is not oversized (discharge rate not exceeding three times the inflow rate), and for pumps receiving discharge from toilets and food establishments, a minimum free passage of 64mm with a discharge pipe larger than that.
Components of a sump pump system
A typical duplex sump pump system is built from the following parts. Sizes and quantities are matched to your pit and inflow on quotation.
| Component | Details |
|---|---|
| Sump pumps | Two submersible pumps installed to pump out the water collected in the sump pit, arranged duty and standby |
| Control panel | Controls the operation and alternation of the sump pumps, with overload protection and fault alarm |
| LED indicators | Show the operation of each pump and help verify the condition of the parts in the system at a glance |
| Float switches | Two to four normally open float switches that start and stop the pumps based on the waste water level |
| Guide rails | Allow the pump to be lifted straight out of the pit for servicing without entering or draining the sump |
| Check valves | Prevent discharged water from flowing back down into the pit when the pump stops |
| Gate valves | Isolate each pump so one can be serviced while the other keeps the pit clear |
| Rubber hoses | Flexible connections that absorb vibration and simplify pump removal |
Why guide rails are worth it: without them, servicing a submersible pump usually means draining the pit and entering it, which is confined space work. With guide rails the pump lifts out on its own rails and drops back onto the discharge connection, so routine servicing is faster, cheaper and far safer.
Where sump pump systems are installed
- Basement car parks and rainwater sumps
- Commercial buildings and office towers
- Industrial buildings and factories
- Shopping complexes and mixed developments
- Hospitals, schools and institutions
- Condominiums and residential developments
- Any building with floors, basements or car parks built below the public drain level
Brands we carry
We keep most of these brands in our warehouse to avoid delays in delivery and installation, and we select the pump on the water being handled, the solids in it, the head required and the pit dimensions.
Tsurumi
Heavy-duty drainage
Grundfos
Drainage & sewage
Wilo
Submersible range
Lowara
Compact submersible
Calpeda
General duty
Goulds & Vossche
Also available
Recent installations
Common sump pump problems we fix
Most sump pump failures come down to a handful of causes, and almost all of them are cheaper to fix than the flood they cause.
Pump does not start
Usually a stuck or tangled float switch, a tripped overload in the panel, or a burnt-out motor after repeated dry running.
Pump runs but water stays
A blocked impeller or strainer, a jammed check valve, or debris and silt in the pit restricting flow.
Pump keeps cycling
A faulty check valve letting discharged water run back into the pit, or float switch levels set too close together.
Only one pump ever runs
Failed alternation in the control panel, so one pump wears out while the standby sits idle and seizes.
Pit overflows in heavy rain
An undersized system for the actual inflow, a standby pump already out of service, or a partly blocked discharge line.
Noise, vibration or tripping
Worn bearings or mechanical seal, a damaged impeller, or perished rubber hoses and loose connections.
Our services for sump pump systems
New system
For a new sump pump system
- Design the pump system from your drawing, or collect the consultant's drawing with the pump requirements.
- Suggest a few suitable brands for your selection.
- Quote based on the brand you choose.
- Install the system, including testing and commissioning.
Repair
For a faulty sump pump system
- Visit your premises at a time convenient to you.
- Identify the problem in the existing system or parts.
- Give an obligation-free quotation for the repair or replacement works.
- On your approval, carry out the corrective works.
Servicing and maintenance
Sump pits collect silt, grit, rags and debris, and that is what wears out impellers and jams float switches. Scheduled pump maintenance works keep the system reliable, and matter more here than on most pumps, because a sump pump usually sits idle until the day it is badly needed. A visit typically covers cleaning out the pit, checking and freeing the float switches, testing pump alternation and the standby pump, inspecting check and gate valves, and confirming the panel alarms operate.
Our certifications
BCA ME11
Mechanical Engineering, L1
BCA GB1
General Builder Class 1
bizSAFE Star
Workplace Safety & Health
ISO 9001:2015
Quality Management System
Warranty
One-year warranty on parts we install
All spare parts we use are genuine parts supplied by globally recognised manufacturers. We provide a one-year warranty against products changed and/or installed by Waves Fluid Engineering Pte Ltd at your premises (subject to terms and conditions).
Related pump systems & services
All water pump systems
Ejector pump system
Transfer pump system
Pantry pump system
Pump maintenance works
Float switch
Frequently asked questions
What is a sump pump system?
It is a pump, or set of pumps, installed in a sump pit to remove water that collects at a low point of a building and lift it to where it can drain away. It is used where the collection point sits below the level of the drain or sewer, so gravity drainage is not possible. Float switches start and stop the pumps automatically as the water level rises and falls.
What is a sump pit?
The sump pit is the chamber that collects the water before it is pumped out. It can be a purpose-built pit in a basement or car park, a waste water collection box, or a trench. The pit needs enough storage capacity for the expected inflow, and it should be accessible for cleaning, because silt and debris collecting in it are the main cause of pump failure.
How many sump pumps does a basement need?
For a basement pumped drainage system, PUB's Code of Practice on Surface Water Drainage requires standby redundancy: at least N duty plus 1 standby for general developments, and at least N duty plus N standby for other development types, where N is the number of pumps needed to achieve the design capacity. The system must also be supported by a generator if main power fails. Your Qualified Person confirms the exact configuration for your project.
Where does a basement sump pump discharge to?
A basement pumped drainage system should not discharge directly into the roadside or public drain. The discharge is taken through a swan neck connection into the development's internal drain or internal sump before it is conveyed to the roadside drain, and the minimum crest level requirement applies. A used water sump is different: it discharges to the inspection chamber and sewer.
What is the difference between a sump pump and an ejector pump?
A sump pump clears water collected in a pit, most commonly rainwater and seepage in a basement or car park. An ejector pump handles waste water from toilets and other fixtures located below the sewer line and lifts it up to the sewer. A sump pump is often installed inside an ejector pit as part of that system, which is where the two overlap.
Why does my sump pump keep running or keep tripping?
Constant running is usually a faulty check valve letting discharged water flow back into the pit, or float switch levels set too close together. Tripping usually points to a blocked or jammed impeller, worn bearings or a failed mechanical seal drawing excess current. Both are worth attending to quickly, because repeated cycling and overload wear out the motor.
How often should a sump pump be serviced?
We recommend scheduled servicing, typically quarterly, depending on how much silt and debris the pit collects. A sump pump usually sits idle until it is urgently needed, so a service visit that cleans the pit, frees the float switches and proves the standby pump actually runs is what prevents a flood. Maintenance contracts are available.
What are guide rails and do I need them?
Guide rails let a submersible pump be lifted straight out of the pit for servicing and lowered back onto its discharge connection, without draining the pit or entering it. Since entering a sump pit is confined space work, guide rails make routine servicing faster, cheaper and considerably safer. We recommend them on any pit that will be serviced regularly.
Which sump pump brands do you supply?
We carry Tsurumi, Grundfos, Wilo, Lowara, Calpeda, Goulds and Vossche, among others, and keep most of them in our warehouse to avoid delays in delivery and installation. We select the pump on the water being handled, the solids content, the head required and the pit dimensions.
Do you repair sump pumps installed by another company?
Yes. We visit at your convenience, identify the fault in the existing system or parts, provide an obligation-free quotation, and carry out the repair or replacement on your approval, whatever the brand and whoever installed it.
Can you upgrade an existing sump pit to a two-pump system?
In most cases yes. We assess the pit dimensions, the actual inflow, the discharge route and the available power supply, then quote for the additional pump, control panel, float switches, guide rails and valves. Upgrading is common where a single pump has become a single point of failure for a car park or basement.
Do you provide a warranty?
Yes. We use genuine spare parts from globally recognised manufacturers and provide a one-year warranty on products changed and/or installed by us at your premises, subject to terms and conditions.
Need a sump pump installed, repaired or upgraded?
Call or WhatsApp +65 9487 0446 or email sales@wavesfluid.com.sg for a site visit and quotation.
