The pump gets most of the attention, but the well decides how a pump station behaves. Too small and the pump short-cycles and there's no reserve when something goes wrong. Too shallow and the incoming drain enters below the pump's switching levels. Too narrow and two pumps won't fit with room to service them.
This guide uses the Maxijet MPPS polyethylene pump wells as the worked range. Per the listing, they're made from hexene-based polyethylene for stormwater and sewage transfer and rainwater retention, sold as a bare well or pre-plumbed for one or two pumps. Pumps are sold separately.
The range
| Model | Volume | Diameter x depth | Well only | Single pre-plumbed | Dual pre-plumbed |
|---|---|---|---|---|---|
| MPPS100 | 100L | 450 x 700mm | $1,200.05 | $1,920.55 | n/a |
| MPPS250 | 250L | 730 x 875mm | $1,480.55 | $2,025.05 | $2,300.05 |
| MPPS700 | 700L | 1150 x 1100mm | $2,481.55 | $3,026.05 | $3,741.05 |
| MPPS1200 | 1200L | 1150 x 1660mm | $3,026.05 | $3,840.05 | $4,659.55 |
| MPPS1600 | 1600L | 1200 x 2000mm | $4,120.55 | $4,912.55 | $5,435.05 |
| MPPS2000 | 2000L | 1200 x 2500mm | $5,660.55 | $6,815.55 | $7,591.05 |
| MPPS3000 | 3000L | 1600 x 2125mm | $7,024.55 | $7,992.55 | $8,394.05 |
| MPPS5000 | 5000L | 1925 x 2500mm | $9,961.55 | n/a | $11,254.05 |
The 100L to 1200L wells come with a Class A poly access cover. Guide rails are standard on the 3000L and 5000L wells, and available on request for other sizes. Pre-plumbed versions include a 50mm swing check valve, 50mm ball valve and 50mm union per pump, plus a 50mm common outlet.
1. Volume
A well's volume does two jobs:
- Working volume, between the pump's start and stop levels. Too little and the pump starts and stops constantly, which wears it out.
- Emergency storage, above the high level alarm. This is what holds incoming flow while a failed pump is fixed or the power comes back. For sewage, it's often the figure your local authority sets a minimum for, based on the number of fixtures or the expected daily flow.
Work out the emergency storage first, then add working volume and the space below the pump's stop level.
2. Depth
Depth is set by the incoming drain. The inlet has to enter the well above the high level alarm, and the drain needs its proper fall from the furthest fixture to the well. On a long or deep drainage run, that can push the inlet well below ground, which is why the bigger wells are also deeper. Check the inlet invert level on your drainage plan against the well depth before choosing.
3. Diameter and pump layout
A single small pump fits a narrow well. Two pumps for duty/standby need room to sit side by side, with floats that don't foul each other and space to lift each one out. That's why dual pre-plumbing starts at the 250L well and the larger diameter wells suit dual pumps best. For deeper wells, a guide rail kit lets you lift a pump out without anyone going into the well.
4. Lid rating
The supplied Class A cover is for pedestrian and non-trafficable areas. If a vehicle could drive over the well, it needs a cover rated for that load. Contact PSA about trafficable covers for your well size.
Well only or pre-plumbed?
Pre-plumbing adds the check valves, ball valves and unions inside the well. On the 1200L well, single pre-plumbing adds $814.00 and dual adds $1,633.50 over the bare well. That's usually worth it: those valves have to go in anyway, and doing it in the factory saves working inside the well on site.
If you want everything in one box for a single house, see our guide to packaged pump stations. For small stormwater pits in a backyard, see Hyjet Minipits. Installation must follow AS/NZS 3500.2 (sewage) or AS/NZS 3500.3 (stormwater) and your local authority's requirements.
Frequently Asked Questions
How big should a pump well be?
Big enough for the working volume between pump start and stop, plus emergency storage above the high level alarm. Local authorities often set a minimum emergency storage for sewage.
What's included in a pre-plumbed Maxijet MPPS well?
A 50mm swing check valve, 50mm ball valve and 50mm union for each pump, plus a 50mm common outlet. Pumps are sold separately.
Do Maxijet pump wells come with guide rails?
Guide rails are standard on the 3000L and 5000L wells and available on request for other sizes.
Can I drive over a pump well with a Class A lid?
No. Class A covers are for pedestrian and non-trafficable areas. Vehicle areas need a cover rated for the load.