To choose a submersible pump, calculate the flow you need (m³/h) and the total head (m), match the pump type to the liquid and solids, check the power supply, and pick materials that suit the water. Then compare the pump curve with your duty point and add a 10–20 % margin.
Submersible pumps are the standard solution for sumps, pits, boreholes and tanks in the UAE, but the range is wide: drainage pumps, sewage cutters, construction dewatering pumps, deep-well pumps and pond pumps all look similar and do very different jobs. Use the five checks below to narrow it down quickly.
1. Work out the flow you need
Flow is how much water must move per unit of time. For a pit that must be emptied, divide the volume by the time you can allow. A 30 m³ basement sump that should be emptied in 2 hours needs about 15 m³/h. For a continuous process, use the process flow.
| From | To | Multiply by |
|---|---|---|
| L/min | m³/h | 0.06 |
| m³/h | L/min | 16.67 |
| L/s | m³/h | 3.6 |
| US gpm | m³/h | 0.227 |
2. Calculate the total head
Total head = static lift + friction losses + required outlet pressure. Static lift is the vertical distance from the water level in the pit to the highest point of the discharge pipe. Friction depends on pipe length, diameter and fittings; as a rule of thumb, long, narrow pipes can add several metres. Always add a margin of 10–20 %.
3. Match the pump to the liquid
The wrong impeller is the most common cause of premature failure. Use this table as a starting point.
| Liquid | Typical solids | Recommended pump type |
|---|---|---|
| Clean or lightly dirty water | None to fine silt | Pond / drainage pump (½–3 hp) |
| Ground / rain water with sand and silt | Fine to medium solids | 3-phase DSP drainage pump |
| Abrasive water, slurry, quarry or site water | Sand, grit, small stones | DSP 3-phase drainage pump (abrasion-resistant) |
| Domestic or commercial sewage | Fibres, paper, wipes | Sewage cutter pump |
| Borehole water | None | Deep well pump (BORE) |
4. Check the power supply
Small pumps (up to roughly 3 hp) usually run on single-phase 230 V; larger pumps use three-phase 400 V. Confirm voltage, frequency (50 Hz in the UAE), starter type and cable length at the pump location before you order. Remember that 1 hp ≈ 0.75 kW.
5. Choose the right materials
Cast iron suits most drainage work. For abrasive water choose a hard impeller such as high-chromium alloy; for corrosive, saline or chemically treated water choose stainless steel or specialised materials. UAE conditions — high temperature, humidity and salty groundwater — make material choice important.
A simple 5-step selection checklist
- Note the duty: flow (m³/h) and total head (m).
- Identify the liquid: clean, silty, abrasive or sewage.
- Pick the pump family using the table above.
- Check supply & control: voltage, starter, float switches.
- Compare the curve with your duty point and add margin.
Common mistakes to avoid
- Buying by horsepower alone instead of by flow and head.
- Ignoring friction losses in long or narrow discharge pipes.
- Using a drainage pump on sewage and then wondering why it blocks.
- Running pumps dry because the sump is too shallow or the float is mis-set.
- Forgetting a non-return valve on the discharge line.
Not sure? Send your numbers to our team on WhatsApp or use the quote form and we will size the pump with you.
Frequently asked questions
How do I calculate total head for a submersible pump?
Total head = vertical lift from pump to discharge point + friction losses in the pipe and fittings + any pressure required at the outlet. Add 10–20 % margin.
How many m³/h is 1 L/min?
1 L/min = 0.06 m³/h, so 100 L/min = 6 m³/h. To convert m³/h to L/min multiply by 16.67.
Is a bigger pump always better?
No. An oversized pump short-cycles, wastes energy and wears faster. Choose a pump whose curve delivers your duty point near its best-efficiency range.
What if I am not sure what liquid I have?
Tell us what is in the pit — sand, silt, rags, grease, chemicals — and we will recommend an impeller type and materials.