How Much Sand Can a Deep Well Submersible Pump Handle?

Sand is one of the most common causes of premature wear in a deep well submersible pump.

A pump may continue delivering water while sand is gradually damaging its impellers, diffusers, bearings and check valve. By the time flow or pressure falls noticeably, expensive internal wear may already have occurred.

The safe sand limit is not universal. It depends on the exact pump design, material, particle size, operating time and well condition. Always compare a tested water sample with the limit stated for the selected pump model.

Why Sand Enters a Borehole Pump

• Incomplete well development

• Damaged or incorrectly selected well screen

• Excessive pumping rate

• Pump installation too close to the well bottom

• Rapid starting and stopping

• Changes in groundwater level

• Casing or gravel-pack failure

• Sediment disturbed during installation

A new well may initially produce cloudy water, but persistent sand should not be treated as normal pump operation. The cause should be investigated with the well contractor.

Sand Content Is More Than One Number

Sand concentration may be reported as a percentage, parts per million, milligrams per litre or a volume collected during a timed test. These units are not automatically interchangeable without knowing whether the result is based on mass or volume.

Particle size also matters. A small quantity of coarse sand can block narrow passages, while fine abrasive particles may pass through the pump and cause continuous surface wear.

A useful review should include:

• Total suspended solids

• Sand concentration

• Particle-size distribution

• Hardness and shape of particles

• Test method

• Sampling time and pumping flow

Do not approve a pump from a visual inspection alone. Water that appears clear can still contain damaging fine particles.

What Does the SLAPK Catalogue Specify?

The referenced SLAPK QJ catalogue lists a solid-content condition of no more than 0.01% for the applicable configuration. Its troubleshooting section also advises checking whether well sediment is excessive when bearings or bushings wear.

This value should not be applied to every SLAPK product or every submersible pump. Sewage, slurry and drainage pumps are designed for different solids. Even within a clean-water range, permitted concentration and particle size can vary.

Confirm the exact model, material and approved water conditions before ordering.

How Sand Damages the Pump

Impellers and Diffusers

High-speed particles repeatedly strike the hydraulic surfaces. Edges become rounded, clearances increase and the pump gradually loses head and efficiency.

Bearings and Bushings

Water-lubricated bearings depend on clean water between moving surfaces. Abrasive particles can increase clearance, shaft movement, noise and vibration.

Check Valve

Sand can collect on the seat or guide, preventing complete closure. This may allow reverse flow, pressure loss and reverse pump rotation after shutdown.

Motor and Mechanical Components

Sand normally passes through the hydraulic section rather than the sealed motor. However, increased vibration and bearing wear can place additional stress on the coupling, shaft and motor thrust system.

Warning Signs of Excessive Sand

Look for:

• Sand settling in a sample container

• Cloudy or gritty discharge water

• Falling flow or pressure

• Rising or unstable motor current

• Increased vibration or noise

• Frequent check-valve problems

• Short bearing life

• Metal or plastic wear particles

• Sand appearing after every start

One symptom does not prove that sand is the cause. Low flow can also result from reverse rotation, low voltage, excessive head, a closed valve or a leaking rising main.

How to Collect a Useful Water Sample

Sample the water while the pump is operating at a measured flow. Record:

• Date and time

• Pumping duration

• Flow rate

• Static and dynamic water levels

• Sampling point

• Appearance of the water

Samples taken only during the first seconds after startup may show disturbed sediment that does not represent stable operation. However, the startup condition is still important if the pump experiences it every day.

For important municipal, industrial or irrigation wells, use a qualified laboratory or well specialist to determine concentration and particle size.

Check Pump Installation Depth

The pump should remain far enough above the well bottom to avoid accumulated sediment while maintaining adequate submergence below the dynamic water level.

The referenced SLAPK QJ installation instructions specify a model-related minimum distance between the motor bottom and the well bottom. Use the value supplied for the exact pump rather than applying one distance to every installation.

Also review the position of the well screen. Installing the pump beside an unstable or damaged screen may increase the amount of sand entering the intake.

Control the Pumping Rate

A pump can produce more water than the well can supply safely. Excessive flow increases water velocity through the screen and surrounding formation, which may carry more sand into the casing.

During commissioning, open the discharge valve gradually and record:

• Flow

• Pressure

• Motor current

• Dynamic water level

• Sand or turbidity

If sand increases sharply as flow rises, reduce the operating rate and consult the well specialist. Do not keep the pump at maximum flow simply because the motor current remains acceptable.

A VFD may help control flow, but it cannot repair a damaged screen or poorly developed well.

Should You Choose Stainless Steel?

Stainless steel can improve corrosion resistance, but it does not make a pump immune to abrasion.

Sand resistance depends on the complete design, including:

• Impeller and diffuser materials

• Shaft and bearing materials

• Surface hardness

• Hydraulic clearances

• Bearing arrangement

• Operating speed

Select material from both the water chemistry and abrasive conditions. A corrosion-resistant material may still wear quickly in a sandy well.

What to Do When Sand Is Excessive

Do not rely only on installing a new pump. First identify the source of the sand.

Possible actions include:

1. Reduce the pumping rate.

2. Measure the dynamic water level.

3. Check pump depth and well-bottom clearance.

4. Redevelop the well.

5. Inspect the screen and gravel pack.

6. Repair damaged well components.

7. Select a pump specifically approved for the measured solids.

8. Monitor sand after corrective work.

A surface filter may protect downstream equipment, but it does not prevent sand from passing through and wearing the pump.

Common Mistakes

Avoid selecting a pump from the word “sand-resistant" alone, using one sand limit for every model, placing the pump on the well bottom, operating at excessive flow, judging water only by appearance or replacing worn pumps without correcting the well.

Frequently Asked Questions

Can a clean-water borehole pump handle some sand?

Many models tolerate only a limited amount. Use the exact manufacturer's concentration and particle-size limits.

Does more pump power solve a sand problem?

No. A larger pump may increase screen velocity and draw even more sand from the formation.

Will a surface filter protect the pump?

No. The water and sand pass through the pump before reaching a surface filter.

Can a VFD reduce sand production?

Reducing speed and flow may help when excessive pumping is the cause, but a VFD cannot correct a damaged or unsuitable well screen.

When should the pump be stopped?

Stop or reduce operation when sand exceeds the pump limit, performance changes rapidly, current becomes abnormal or severe vibration occurs.

Conclusion

Sand tolerance must be confirmed for the exact pump and well. Test the water, measure particle size, verify pump depth and operate within a sustainable flow range.

If sand remains excessive, correct the well condition before relying on a replacement pump. This protects the hydraulic components, bearings, check valve and long-term system performance.

Request a Pump Selection Review

Send SLAPK your required flow and head, well depth, water levels, installation depth, water analysis, measured sand content and particle size.

Our engineers can recommend a suitable QJ or SP pump and confirm the applicable material and water-quality limits.

Contact SLAPK for a deep well pump recommendation