By the Jordan Pumps team, Kempton Park | Pumps You Can Trust
Before you think about kilowatts, flow or head, there’s one question that decides which borehole pump you can buy: will it fit down the hole? Borehole pumps come in two common sizes in South Africa, 3-inch and 4-inch, and the size refers to the borehole casing the pump is made for. Pick the wrong one and the pump simply won’t go in, or worse, it goes in and gets stuck.
This guide shows you how to check your borehole pump casing size, what to do if your borehole is narrow, and when a 3 inch borehole pump or a 4 inch submersible pump is the right call.
Already know your casing size? Jump to our Borehole Pump Size Guide to work out how much power you need.
Step 1: Find your casing size
The casing is the pipe that lines your borehole from the surface down. What matters is its inside diameter, because that’s the space the pump has to slide through.
There are two easy ways to find it:
- Check your driller’s report. Most drillers record the casing diameter along with the hole depth and the yield test. Look for the casing size in millimetres.
- Measure at the wellhead. Switch off the power to the existing pump first. Remove the borehole cap and measure straight across the inside of the casing, from inner wall to inner wall. Don’t measure the outside of the pipe, because the wall thickness will make the hole look bigger than it is.
If you’re measuring an old borehole and the number is close to a cut-off, take a photo of your tape measure across the casing and send it to us. We’ll help you decide before you buy.
Step 2: Match the casing to the pump
Here’s the rule we use at Jordan Pumps:
- A 3-inch borehole pump needs a casing of at least 80 mm.
- A 4-inch borehole pump needs a casing of at least 110 mm.
So in practice:
- Under 80 mm: neither size will fit. Don’t try to force a pump down. Speak to your driller or contact us about your options.
- 80 mm up to (but not including) 110 mm: choose a 3-inch pump.
- 110 mm or more: a 4-inch pump fits, and so does a 3-inch.
The pump needs room around it so it can be lowered and pulled up again for maintenance without jamming. That’s why the minimum casing is always bigger than the pump’s own size.
What if my borehole is narrow?
Narrow casings are common in older boreholes. If yours measures 80 mm or more but less than 110 mm, a 4-inch pump is not an option, however tempting the bigger range may be. A 3-inch pump is made for exactly this situation.
Jordan stocks 3-inch pump sets in three sizes, each supplied as a pump, motor and control box for a 220V single-phase supply:
- 0.25 kW 3-inch pump, motor and control box (220V)
- 0.37 kW 3-inch pump, motor and control box (220V)
- 0.55 kW 3-inch pump, motor and control box (220V)
If your water need is bigger than the 3-inch range can handle, the fix isn’t a 4-inch pump in a 3-inch hole. Talk to us, and we’ll help you look at your options.
When to choose a 4-inch pump
If your casing is 110 mm or wider, a 4-inch submersible pump gives you the most choice. Our 4-inch pump sets run from 0.37 kW all the way to 2.2 kW, so there’s more room to match the pump to a deep hole or a big daily demand.
The 4-inch range is also where you’ll find our ready-to-install borehole combo kits. For example:
- The 0.37 kW 4-inch borehole combo kit includes the motor, pump (4SDM2/8), control box, 50 m of spliced submersible cable, 50 m of safety rope and a manual.
- The 0.75 kW 4-inch borehole combo kit uses the SDM2/15 pump and includes the motor, control box, 80 m of spliced 1.5 mm submersible cable, 80 m of safety rope and a manual.
Both kits run on 230V power, from the grid or a generator. We recommend fitting a non-return valve with either one.
On a three-phase (380/400V) farm supply? Our 380V pumps and motors are 4-inch too, and they’re sold as a pump and motor without a control box.
3-inch vs 4-inch at a glance
| 3-inch pump | 4-inch pump | |
|---|---|---|
| Minimum casing | 80 mm | 110 mm |
| Best for | Casings from 80 mm up to 110 mm | Casings of 110 mm or more |
| Jordan sizes | 0.25, 0.37 and 0.55 kW | 0.37 kW to 2.2 kW |
| Supply (Jordan sets) | 220V single-phase | 220V sets, plus 380V/400V pump and motor options |
| Combo kits available | No, pump sets only | Yes: 0.37, 0.55 and 0.75 kW (SDM2/15) |
Once you know the size, pick the power
Diameter tells you which pump fits. Power tells you which pump will do the job. For that you’ll need your pumping water level, how high you’re pushing the water and how much you use each day. Our Borehole Pump Size Guide walks you through it step by step, and the Pump Selector Tool does the maths for you.
Frequently asked questions
Does “3-inch” or “4-inch” mean the size of the borehole?
It refers to the casing the pump is designed for. You still need to check your casing’s inside diameter: at least 80 mm for a 3-inch pump and at least 110 mm for a 4-inch pump.
Can I put a 3-inch pump in a 4-inch borehole?
Yes. A 3-inch pump fits any casing of 80 mm or more, so it will fit a 110 mm casing too. Just make sure its power suits your depth and water needs.
Can I put a 4-inch pump in a casing smaller than 110 mm?
No. Below 110 mm, go with a 3-inch pump. Forcing a pump into a casing that’s too narrow risks it getting stuck down the hole.
My borehole is narrower than 80 mm. What now?
Neither standard size will fit. Chat to your driller or contact us before you buy anything.
Do you deliver, and can I pay over time?
Yes. Jordan Pumps delivers nationwide from Kempton Park, and you can spread the cost with Payflex at checkout.
Ready to find your pump?
Measured your casing? Browse our 3-inch pump sets, 4-inch pump sets or borehole combo kits.
We deliver nationwide, and you can pay with Payflex to spread the cost.
Still not sure which size fits? Send us your driller’s report or a photo of your casing measurement. Call +27 82 888 0118, email sales@jordangroup.co.za or contact us.
Jordan Pumps: Pumps You Can Trust.
