Pump Station Sizing Calculator for Australian Homes and Sites
Work out the right sewer, greywater or stormwater pump station in about a minute. Tell us what it serves and how high and far it pumps, and get the tank size, the pump you need and the packaged stations that fit.
- Sewage, greywater and stormwater
- Works out tank size, pump head and flow
- Matches real packaged stations with prices
Pump stations that fit your job
Each option below meets your storage and head.
How to size a pump station
A pump station is sized on three numbers: how much wastewater comes in each day, how much reserve you want if the pump or power fails, and how hard the pump has to push to get it to the sewer. For a typical family home of four or five people pumping 3 m up and 25 m across, that works out to a 900 litre station with a pump delivering at least 57 litres a minute at about 4 m of head.
Most sizing mistakes come from looking at tank size alone. The tank buys you time. The pump does the work, and it has to beat the full lift plus the friction in the discharge pipe. This pump station sizing calculator checks both, then matches packaged stations that pass on each.
Quick guide: pump station size by household
The table assumes sewage from a home, a 6 hour reserve, and a 3 m lift over 25 m of 50 mm pipe. Use it as a starting point, then run the calculator with your own details.
| Who it serves | Daily flow | Station | Reserve |
|---|---|---|---|
| Granny flat, 2 people | 360 L | 250 L | 10 hours |
| Small home, 3 people | 540 L | 250 L | 7 hours |
| Family home, 4 people | 720 L | 900 L | 23 hours |
| Family home, 5 people | 900 L | 900 L | 19 hours |
| Large home or duplex, 8 people | 1,440 L | 900 L | 12 hours |
| Small commercial, 30 people | 1,500 L | 900 L dual | 11 hours |
Daily flow uses about 180 litres per person for a home and 50 litres per person for a workplace. Reserve is how long the tank holds normal use if the pump or power stops.
Working out the head
Head is the height the pump has to lift the water plus the friction it loses along the pipe. Measure the lift from the bottom of the pit to the highest point the discharge pipe climbs, not just to the sewer connection, because the pump has to get over that high point. Our guide to calculating head height for a pump station walks through it step by step.
Pipe size matters more than most people expect. Over a 50 m run at the minimum flow that keeps solids moving, friction adds:
| Discharge pipe | Minimum flow | Friction over 50 m |
|---|---|---|
| 32 mm | 30 L/min | 2.0 m |
| 40 mm | 37 L/min | 0.9 m |
| 50 mm | 57 L/min | 0.7 m |
| 65 mm | 102 L/min | 0.5 m |
The calculator adds a 10 percent safety margin on top and checks it against each pump's published maximum head and flow.
Choosing the right pump type
- Sewage from a toilet needs a cutter, grinder or macerator pump that breaks up solids before they reach the pipe. See grinder pump vs drainage pump and macerator vs grinder pump.
- Greywater from showers, basins and laundries can use a drainage or vortex pump, and one or two fixtures can often use a compact undersink unit from our undersink pump stations.
- Stormwater uses a drainage pump sized to keep up with the heaviest rain. Browse stormwater pits and pumps.
Putting a drainage pump on sewage is the most common and most expensive mistake on these systems. It will block.
Sizing a stormwater pit and pump
A stormwater pump has to keep up with the peak runoff in a heavy storm, which depends on the area draining to the pit and where you live. Hard surfaces like concrete and roofs shed almost all of it.
| Paved area | Brisbane | Sydney | Perth | Melbourne |
|---|---|---|---|---|
| 20 m² | 66 L/min | 60 L/min | 42 L/min | 39 L/min |
| 50 m² | 165 L/min | 150 L/min | 105 L/min | 98 L/min |
| 100 m² | 330 L/min | 300 L/min | 210 L/min | 195 L/min |
Peak flow in a short, heavy design storm, rounded. Your plumber will confirm the local rainfall figure.
Our guide to stormwater pit sizing and the one on drainage for low-lying blocks cover the details.
Single or dual pump?
A single pump station suits most homes. Step up to a dual pump station when a failure would shut down a business, a duplex or a busy household. Two pumps share the load and the second takes over if one fails, so the site keeps running while you arrange a repair.
How accurate is this calculator?
It is a sizing estimate using standard pipe friction methods and each pump's published head and flow, and it leans slightly generous so you are not left short. It does not replace a design by a licensed plumber, who confirms the connection, the local reserve rule and any council or water authority approval. See do you need council approval for a pump station.
If you would like a second opinion before ordering, send your details for a free, builder-ready quote or call 1300 930 847.
Keep reading
Pump station size: common questions
What size sewer pump station do I need for a house?
For a typical family home of four or five people, a 900 litre pump station is the usual choice. It gives around 19 hours of reserve if the pump or power stops. A granny flat or small home with two or three people usually fits a 250 litre station, and a single basement bathroom can often use a compact 40 litre lifting station.
How do I work out the head for a pump station?
Add the vertical lift, measured from the bottom of the pit to the highest point the discharge pipe climbs, to the friction loss in the pipe. For a typical house on a 50 mm pipe, friction is small: about 0.3 m for a 25 m run and about 1.3 m for 100 m. Smaller pipes add much more, around 4 m over 100 m of 32 mm pipe.
How much storage should a pump station have?
Enough to cover a pump failure or power cut without overflowing. A common approach is at least six hours of normal use, which is about 225 litres for a five person home. Some councils and water authorities set their own figure, so your plumber should confirm the local requirement.
Do I need a grinder pump or a drainage pump?
Anything with a toilet needs a cutter, grinder or macerator pump that breaks up solids. A plain drainage pump will block on sewage. Greywater and stormwater can use a drainage pump. Read more in grinder pump vs drainage pump.
When do I need a dual pump station?
Choose a dual pump station when a failure would shut down a business, a multi-dwelling site or a busy home. Two pumps share the work and one takes over if the other fails. See single vs dual pump stations.
What size stormwater pump do I need?
Size it to the peak runoff from the area draining to the pit. In a heavy Sydney storm, 50 square metres of concrete sheds about 150 litres a minute, so you need a pump that moves at least that at your head, and a pit of around 250 litres. The same area in Melbourne sheds about 100 litres a minute.
Want us to check it before you order?
Send your fixtures, lift and pipe run and we will confirm the right station, free. Australian owned, based in Perth, delivering pre-assembled stations nationwide.