Pump Station Access Cover Class: A to G Explained
A pump station access cover class is the load rating on the pit lid, set by AS 3996 and running from Class A at the light end to Class G at the heaviest. It tells you what can sit on or drive over the lid without it failing. For a domestic sewer or stormwater pump station, Class A suits pedestrian areas only, Class B suits a domestic driveway or car park, and Class D is what you specify under a road or anywhere trucks go. Get it wrong and you are cutting concrete to fix it.
Not sure what size you need? Try our sewer pump station calculator. It works out the tank size, pump head and the packaged stations that fit your job.
Written for the builder who just realised the driveway is going straight over the pit.
That is the answer. Here is the detail, because the class you need is usually decided by something on the plans that nobody flagged.
What the class number actually measures
The class is a proof load the cover has to survive during testing, expressed in kilonewtons, under AS 3996 Access Covers and Grates. It is not a weight limit sticker and it is not a fatigue rating. A Class B cover is proof tested to 80 kN. That does not mean you can park an 8 tonne truck on it every morning for ten years and expect it to hold.
So treat the class as a category, not a budget to spend down to. If your site is borderline between two classes, go up. The price difference between classes is small next to the cost of lifting concrete.
Two other things the class does not cover. It does not tell you the lid is gas tight or odour sealed, which matters on a sewer pit. And it does not tell you the frame suits your pit opening. Check both separately.
The classes, A to G
Seven classes, and most people only ever deal with three of them. The table is the whole range so you can find yours, then the sections below cover the ones that come up on real jobs.
| Class | Test load | Rough equivalent | Where it belongs |
|---|---|---|---|
| A | 10 kN | about 1 tonne | Lawn, garden bed, paving, footpath. No vehicles. |
| B | 80 kN | about 8 tonnes | Domestic driveway, car park, slow moving light vehicles. |
| C | 150 kN | about 15 tonnes | Commercial yards and loading areas off the main carriageway. |
| D | 210 kN | about 21 tonnes | Roads, carriageways, anywhere heavy vehicles run. |
| E | 400 kN | about 40 tonnes | Industrial pavements, container and freight yards. |
| F | 600 kN | about 60 tonnes | Docks and aircraft pavements. |
| G | 900 kN | about 90 tonnes | Highest wheel loads. Airport aprons and specials. |
Test loads are the AS 3996 proof loads. The tonnage column is a rough conversion for scale only, not a working load limit. Your hydraulic consultant or licensed plumber confirms the class for the site.
Class A: pedestrian areas, and nothing else
Class A is for places a vehicle never goes. Lawn, garden bed, a paved path down the side of the house, a courtyard. That is the whole brief.
This is the class that gets people into trouble, because it is the cheap one and the pit is often sitting in grass at the time the order goes in. Then the landscaper extends the hardstand, or the owner decides the trailer lives round the side, and a cover rated for a person walking on it is now under a wheel.
Our 600 x 600mm Class A Poly Access Cover is $208.95. Polymer, anti slip pattern, 600 x 600mm nominal frame. It will not rust and it is light enough for one person to lift, which is the real argument for poly over metal in a domestic pit you have to open for servicing.
Class B: the domestic driveway class
Class B is the right call for a domestic driveway, a car park bay or any surface where cars and light vans move slowly. If a pump station pit ends up inside the concrete apron at the front of a house, this is your minimum.
The 600 x 600mm Class B Composite Pit Cover is $529.78. Composite rather than cast iron, so it is a fraction of the weight of an equivalent metal lid and there is nothing in it worth stealing. On sites where scrap theft is a problem, that second point is not a small thing.
Class C: the one you rarely buy
Class C sits between a car park and a road, and in practice it gets skipped. Most specifiers jump from B to D because the step up in cost is modest and D removes the argument entirely. If a hydraulic plan calls for Class C specifically, follow the plan. Otherwise it is usually simpler to go to D.
Class D: roads, trucks and anything trafficable
Class D is the trafficable class. Carriageways, commercial driveways, service yards, anywhere a loaded truck or a concrete agitator can end up. If the words "trafficable" or "heavy vehicle access" appear anywhere on the plans near your pit, this is the one.
Three in the range, and the choice between them is about the opening and whether water needs to get in:
- 600 x 600mm Class D Cast Iron Trafficable Pit Cover, $1,185.68. Solid lid, standard 600 square opening.
- 600 x 900mm Class D Cast Iron Trafficable Pit Cover, $1,267.64. Same rating, longer opening, for pits you need proper access into.
- 600 x 600mm Class D Cast Iron Stormwater Grate, $500.51. Grated, so surface water drops through it. For a stormwater pit that is collecting, not a sealed sewer pit.
Prices are Waternex list prices in AUD including GST, current as of September 2026. Trade buyers, see trade pricing.
Classes E, F and G: civil and industrial territory
Classes E, F and G are for container terminals, docks, airport pavements and heavy industrial hardstand, and they are specified by an engineer, not chosen off a shelf. They are special order rather than stock. If your project genuinely needs one, send us the drawing and the required opening and we will price it.
What comes on a packaged pump station by default
Packaged pump stations ship with a light duty lid unless you specify otherwise. That is the correct default for most domestic installs, where the pit sits in a garden bed or a side yard, and it keeps the base price down.
It is also why the upgrade has to be a conscious decision at order time. Nobody on the supply side knows the driveway is being extended next year. You do.
The same applies right across the packaged pump stations range, sewer and stormwater alike. A Kwikflo 250L Sewer Pump Station in a lawn is a Class A job. Put the same unit in the front apron and it is a Class B job at minimum.
How to pick the class for your site
Work it out from the finished surface, not the surface that is there during construction. Three questions do it.
What will be on top of the pit when the job is finished
Look at the landscape plan and the civil plan, not the bare block. Pits that started in dirt end up under pavers, aprons and crossovers more often than anyone admits.
What is the heaviest thing that could ever cross it
Not the family car. The heaviest realistic vehicle. A removalist truck reversing up a residential driveway is heavier than the car that normally parks there, and it will find the pit.
Whether the pit needs opening regularly
Service access changes the material choice more than the class. A cast iron Class D lid is a two person lift with the right keys. If the pit needs opening for routine servicing and the class allows it, a poly or composite lid is far easier to live with. Sizing and service access are covered in more detail in our guide to what size sewer pump station you need.
Retrofitting a cover after the concrete is down
Retrofitting a higher class cover costs several times the price of the cover itself. The frame is set into the surround, so upgrading means breaking out the concrete around the pit, setting the new frame to the finished level, and making good. On a finished driveway that is a saw cut, a breakout, a concrete pour and a cure time.
The cover might be a few hundred dollars. The job around it is usually a four figure number once you count the concreter. Spend the extra at order time instead.
Three mistakes that come up again and again
Specifying off the block as it stands today. The pit gets located during early works and the surface gets decided months later. Spec the cover for the finished plan.
Matching the class but not the opening. A Class D cover in the wrong nominal size does not help you. Confirm the pit opening before ordering, and match the frame to it.
Putting a grate over a sewer pit. A grated lid lets surface water in, which is exactly what you want on a stormwater pit and exactly what you do not want on a sewer pit. Keep the two straight. The same separation logic applies to the pits themselves, covered in stormwater pit sizing for Australian homes.
Frequently asked questions
What access cover class do I need for a domestic driveway in Australia?
Class B is the minimum for a domestic driveway, because Class B is rated for slow moving light vehicles and Class A is not rated for vehicles at all. Step up to Class D if trucks, trailers or delivery vehicles use the driveway.
Can you drive a car over a Class A access cover?
No. Class A is rated for pedestrian areas only, so a car over a Class A cover is outside what the cover was tested for. If a vehicle can reach the pit, you need Class B or higher.
What does trafficable mean on a pit cover?
Trafficable means the cover is rated for vehicles driving over it, which on most Australian plans means Class D under AS 3996. A cover described as pedestrian rated or light duty is not trafficable.
What is the difference between Class B and Class D covers?
Class B is proof tested to 80 kN for car parks and domestic driveways, and Class D is proof tested to 210 kN for roads and heavy vehicle areas. Class D covers in the Waternex range are cast iron and cost roughly twice the composite Class B equivalent.
Do pump stations come with an access cover included?
Yes, packaged pump stations include a light duty cover as standard. Upgrading to a higher load class has to be specified at order time, because retrofitting one after the surface is finished means breaking out concrete around the pit.
What standard covers access cover load classes in Australia?
AS 3996 Access Covers and Grates sets the load classes A to G used across Australia. Every access cover in the Waternex range is rated to AS 3996 and the class is listed on the product page.
Not sure which class the plans call for
Send us the pit opening size, the finished surface over it, and the heaviest vehicle that will cross it. We will tell you the class and whether we have it on the shelf.
Shop sewer pump stations or the wider sewage and stormwater pump station range, and for surface drainage see stormwater pit and pump systems.
Talk to the Waternex team about your site
This guide is general information for Australian conditions and is not a substitute for advice from a licensed plumber or a hydraulic consultant. Access cover load class selection is a design decision that depends on the finished surface, the pit and the traffic over it, and requirements differ between states and water authorities. Have your plumber or engineer confirm the class and the opening before you order.