Borehole Diameter for a Solar Pump: The Constraint You Cannot Buy Your Way Out Of

The short answer: the inside diameter of your borehole is the one design input you cannot change after the fact, and it sets two limits that pull in opposite directions. Too tight and the pump, the cable and the rope will not pass. Too roomy and the water drifts past the motor too slowly to cool it. The single number that ties both together is the annulus velocity:

v = Q x 353 / (D² - d²), where Q is flow in m3/h, D is the casing inside diameter in mm, d is the pump outside diameter in mm, and v comes out in m/s.

Published pump data puts the floor at 0.08 m/s for a 4-inch motor and 0.15 m/s for 6-inch, 8-inch and 10-inch motors. Run a 4-inch pump in a 4-inch casing and you have 3.5 mm of clearance, which will not pass a cable. Run the same 4-inch pump in an 8-inch casing and it must produce 7.29 m3/h of its own water just to keep its own motor cool. Same pump, same hole depth, two completely different problems, and neither number appears on any datasheet you were handed.

This is the companion to our borehole yield test guide, which covers how much water your well can give. This article covers a different question that arrives earlier in the process: whether the pump can physically go down there at all, and whether it can survive once it does.

Two questions a borehole has to answer at once

There are two questions and they are not the same question, which is why so many boreholes end up with the wrong pump in them.

Question	What it depends on	What happens if you get it wrong
Can the pump get down there?	Casing inside diameter minus pump outside diameter, minus everything strapped to the drop pipe	The pump jams on the way down, or it passes at the surface and stops 40 m deep, or the cable is crushed against the casing wall and you have an earth fault you cannot find
Can the motor survive once it is down there?	The water velocity in the annulus, which depends on how much water you are pumping and how much room it has to travel	The motor runs hot, the winding insulation ages fast, the controller derates the drive or the thermal protection trips, and the pump dies in the second or third hot season

The trap is that these two questions are answered by opposite changes. Adding diameter makes the second question easier and the first question no harder. Removing diameter makes the fit look tighter and the cooling look better. There is a band of casing sizes where both answers are yes, and it is narrower than most people assume. That band is the whole subject of this article.

Three diameters get confused with each other constantly, so it is worth fixing the vocabulary before the arithmetic starts:

Name	What it is	Typical value for a 4-inch well	Why it matters
Drill bit diameter	The diameter of the hole in the rock or sediment	4 inch to 12 inch	Tells you nothing about the pump; the casing usually fits inside it
Casing outside diameter	The outer wall of the pipe	about 114 mm for 4-inch PVC	What the driller quotes you and what the well head cap is cut to
Casing inside diameter (ID)	The clear bore the pump travels through	about 102 mm	The only one the pump cares about

That 12 mm between the last two rows is not a rounding error. It is three times the entire radial clearance a 4-inch pump has in a 4-inch casing, and it is lost before anything is installed.

The annulus velocity formula, and how to check it

A submersible motor is cooled by the water flowing past its outside surface. The water is being pumped upward, but in the annulus it first has to travel down past the motor to reach the pump intake, and that downward leg is what carries the heat away. The narrower the space between motor and casing, the faster the same litres have to move.

Manufacturers express this as a velocity rather than a flow, which is why two wells with the same pump and the same yield can have completely different motor temperatures. The published SI form is:

v = Q / (2826 x (Di² - dA²)) with Q in m3/h and both diameters in metres.

Multiply the denominator out and you get the field form used throughout this article, which takes millimetres directly and returns m/s:

v = Q x 353 / (D² - d²)

To go the other way, from a required velocity to the flow you need:

Q = v x (D² - d²) / 353

The thresholds come from published pump and well-construction data. AWWA specifications put the allowable velocity past a motor between 0.5 and 12 feet per second, that is roughly 0.15 to 3.7 m/s, and pump makers run tighter floors for smaller motors:

Motor size	Minimum velocity past the motor	Source
4 inch	0.08 m/s (0.25 ft/s)	Pump maker minimum-cooling-flow tables
6 inch	0.15 m/s (0.50 ft/s)	Same, and AWWA lower bound
8 inch	0.15 m/s	Same
10 inch	0.15 m/s	Same
Upper bound, all sizes	3.7 m/s (12 ft/s)	AWWA maximum, relevant to erosion of the casing

The formula is easy enough to trust on faith, but you should not. It reproduces a published manufacturer table almost exactly, and it is worth doing that check once so you know the arithmetic behind your own well is sound. Here is the comparison, converting the published values from gallons per minute at 0.2271 m3/h each:

Motor	Casing ID	Published minimum flow	Published in m3/h	Computed from the formula	Difference
4 inch	4 inch (102 mm)	1.2 gpm	0.27	0.31	+15%
4 inch	5 inch (127 mm)	7.0 gpm	1.59	1.61	+1%
4 inch	6 inch (152 mm)	13 gpm	2.95	3.19	+8%
4 inch	7 inch (178 mm)	20 gpm	4.54	5.14	+13%
4 inch	8 inch (203 mm)	30 gpm	6.81	7.29	+7%
4 inch	10 inch (254 mm)	50 gpm	11.36	12.58	+11%
4 inch	12 inch (305 mm)	80 gpm	18.17	19.04	+5%
6 inch	6 inch (152 mm)	9 gpm	2.04	1.84	-10%
6 inch	8 inch (203 mm)	45 gpm	10.22	9.54	-7%
6 inch	12 inch (305 mm)	140 gpm	31.79	31.55	-1%

Every row lands within 15%, and that gap is entirely explained by nominal diameters. Manufacturers publish a nominal 4-inch and 6-inch outside diameter; real pump ends are a millimetre or two smaller, which is exactly the margin that shows up in these percentages. What this cross-check buys you is confidence that a formula, a nominal pump diameter and your own casing measurement are enough to make a real decision with. The alternative is to find out empirically, which costs a motor.

A bigger borehole needs more flow, not less

This is the part that surprises people, and it is the reason a pump that ran for years in a narrow well can fail in a new wide one.

Everyone assumes a wide hole is a generous hole. For drilling and for yield that is often true. For motor cooling it is the opposite: every extra millimetre of casing diameter adds annulus area, and the same litres of water then travel more slowly past the motor. The cooling requirement goes up as the square of the diameter, so the penalty for a generous hole grows faster than the hole does.

Take a single 4-inch pump, nominal outside diameter 95 mm, and ask what flow it needs to reach the 0.08 m/s floor in casings of different sizes:

Casing ID	Radial gap per side	Flow needed for 0.08 m/s	Comment
4 inch (102 mm)	3.5 mm	0.31 m3/h	Academic: the pump will not physically pass with a cable attached
5 inch (127 mm)	16.0 mm	1.61 m3/h	The practical minimum casing for a 4-inch pump
6 inch (152 mm)	28.5 mm	3.19 m3/h	Common irrigation choice; comfortable for most 4-inch models
7 inch (178 mm)	41.5 mm	5.14 m3/h	Upper edge; small 4-inch models now cannot keep up
8 inch (203 mm)	54.0 mm	7.29 m3/h	Beyond most 4-inch models at useful heads; sleeve territory
10 inch (254 mm)	79.5 mm	12.58 m3/h	Only high-flow 4-inch models can self-cool here
12 inch (305 mm)	105.0 mm	19.04 m3/h	Sleeve required in practice

Read the middle of that table again. A 4-inch pump in a 6-inch casing needs 3.19 m3/h of its own water to stay cool. The same pump in an 8-inch casing needs 7.29 m3/h. The pump did not change, the hole did. And the requirement more than doubles.

That is why the flow sleeve exists, and it is also why it is worth checking a borehole that was drilled generously for a previous, much larger pump. A 12-inch hole inherited from an old lineshaft installation is not a gift if you are dropping a 4-inch submersible into it.

Now turn the table around and look at it as velocities, which is how it feels in the field. Here is the actual water speed past a 4-inch motor at flows you might really be pumping:

Casing ID	2 m3/h	4 m3/h	6 m3/h	8 m3/h	10 m3/h	15 m3/h
4 inch (102 mm)	0.512	1.024	1.536	2.048	2.560	3.840
5 inch (127 mm)	0.099	0.199	0.298	0.398	0.497	0.745
6 inch (152 mm)	0.050	0.100	0.150	0.201	0.251	0.376
7 inch (178 mm)	0.031	0.062	0.093	0.125	0.156	0.234
8 inch (203 mm)	0.022	0.044	0.066	0.088	0.110	0.165
10 inch (254 mm)	0.013	0.025	0.038	0.051	0.064	0.095
12 inch (305 mm)	0.008	0.017	0.025	0.034	0.042	0.063

The bold cells are the ones that matter for a 4-inch motor running at 6 m3/h, which is a very ordinary operating point. In a 6-inch casing the velocity is exactly at the 0.08 m/s floor with margin to spare. In a 7-inch casing it is already above it but only just. In an 8-inch casing it is below the floor, and the motor is running hot on every one of those litres. Nothing about the pump changed. Only the hole.

The rule this produces: for a 4-inch pump, a 5-inch, 6-inch or 7-inch casing is the sweet spot. Below 5 inches the pump will not pass cleanly; above 7 inches you are relying on either high flow or a flow sleeve.

Physical fit: what actually has to go down the hole

Cooling is the subtle half of the problem. Fit is the half that announces itself, usually at the worst possible moment, with a pump 30 m down and a cable you have to pull back up.

What has to travel down the casing is not just the pump. It is a bundle:

Component	Space it takes in the annulus	Why it cannot be ignored
Pump body and motor	The nominal diameter, 95 mm for a 4-inch pump	This is the part everyone measures
Submersible cable	8 to 12 mm across for a flat 3-core or 4-core cable, plus its sheath	Must run alongside the pump, and it is the item that gets crushed
Cable splice and heat-shrink	Locally thicker than the cable by several millimetres	A splice at the motor end sits exactly where the gap is tightest
Safety rope	4 to 8 mm for stainless wire rope or synthetic rope	Mandatory with flexible drop pipe; must not carry load on the cable
Drop pipe coupling or flange	A collar wider than the pipe	Any coupling wider than the pump body sets the true minimum bore
Non-return valve and foot strainer	Often the widest fitting on the assembly	Many boreholes fail on the valve collar, not on the pump
Water level probe or airstation tube	A few millimetres	A second thin tube alongside the cable adds up

The practical consequence is that the casing has to clear the widest fitting plus the cable bundle, not the pump’s catalogue diameter. With a 4-inch pump in a 4-inch casing you have 3.5 mm per side to work with, and a flat submersible cable is three times that thick. That is why a 4-inch casing and a 4-inch pump is a combination that exists on paper and not in a well, and why the same pump in a 5-inch casing, with 16 mm per side, suddenly becomes a perfectly normal installation.

Published installation guidance converges on the same answer from different directions:

Source	Guidance
Pump maker, 4-inch and 6-inch pump installation manuals	Maintain a consistent inside diameter of 4-inch (102 mm) or 6-inch (152 mm) along the whole casing so the pump lowers freely
Same, for higher-flow models	A 6-inch casing is recommended for 4-inch pumps above about 9 m3/h of rated flow; an 8-inch casing for 6-inch pumps above about 30 m3/h
Same, casing versus motor diameter	Free-convection cooling may be assumed only when the borehole is at least about 50 mm larger than the motor outside diameter; otherwise provide forced flow or a sleeve
Same, pump position	Keep the pump at least 0.30 m above the bottom of the well or borehole, and never let it rest on the bottom
Other makers	Keep the pump at least 1 m, preferably 3 m above the bottom, and at least 1 m below the maximum drawdown level
Field practice in sand-prone wells	Position the intake well clear of the sump and above any screen, and allow for the pumped-down level to drop below the intake if the well is over-pumped

That last row is worth internalising. A pump set 0.3 m off the bottom of a hole that also draws down 20 m during operation needs its cable, rope and valve collar to pass through the entire casing, not just the top few metres, every time it goes in. Fitting at the surface is not the test. Fitting at the tightest section, at depth, at temperature, is the test.

Straight is not the same as plumb

The other way a borehole defeats a pump is by bending. This is regulated, and the regulations are more permissive than most people expect, which is precisely why the pump has to be chosen for the hole rather than the hole assumed to be perfect.

Two different properties are involved. Plumbness or drift is how far the bore wanders off true vertical. Alignment is how straight it is, meaning whether there are dog-legs, kinks or bends. A well can be straight but tilted; a perfectly plumb well is always straight. Alignment is the more important of the two, because a crooked section of casing will stop a pump that a merely tilted one would pass.

Standard	Limit	Notes
AWWA, referenced in well-construction literature	Drift deviation of two thirds of the well inside diameter per 100 feet of depth	For an 18-inch casing that is about 300 mm of wander over 100 ft; generous
EPA, per standard groundwater engineering references	Deviation from plumb of 1 degree per 50 feet	Roughly the same order as the AWWA figure
Modern project specifications	Sometimes as tight as three inches per hundred feet	Owner-driven, not universal
Public water supply well specification, California	Horizontal deviation not exceeding 0.0067 times the smallest casing or screen inside diameter, per foot of depth	A much tighter, measurable form of the same idea
State code, Wisconsin NR 812.19	Plumbness not exceeding 75% of the well diameter per 100 feet, for casing 10 inches and larger; and the well must allow free passage of the pump to the intended setting depth plus 25% of that depth	The 25% clause is the one worth copying into your own specification
Well construction guidelines for developing countries	Plumb within 1% of true vertical, meaning no more than 0.3 m of drift in 30 m, with no noticeable dog-legs, especially where pumping equipment is installed	Also recommends finished sand content below 25 mg/L

The Wisconsin clause is the practical one. If you require a pump to pass the intended setting depth plus 25%, you are testing the hole at the depth the pump will actually work, with margin, rather than testing it at the top where everything passes. Everything else in that table is a tolerance for the driller. This clause is a tolerance for the pump.

Alignment failures are the expensive kind because they are invisible until you are lowering. A 4-inch pump going into a hole with a dog-leg feels fine for the first 20 m and then simply stops. Forcing it is how you crush the cable against the casing wall and end up with an intermittent earth fault that shows up only when the pump warms up.

If a hole has never been logged, it is worth checking before you buy anything, especially if the casing is old, the well is deep, or you are re-equipping someone else’s borehole. A downhole camera survey, a plumbness log, or a simple go-devil of known diameter lowered on a rope will all tell you what you need to know for the price of a few hours. Our guide to handling sand in a solar pump system covers the other thing that goes wrong on the way down, which is abrasive water scoring the pump as it passes.

The flow sleeve: the one part that solves both problems

There is exactly one component in a submersible installation that makes the fit problem easier and the cooling problem easier at the same time, and it is a plain piece of pipe.

A flow sleeve, also sold as a cooling shroud or flow inducer, is a tube that fits over the motor with a gap of a few millimetres, open at both ends. Instead of water wandering slowly up a wide annulus, it is forced to travel down the narrow space between sleeve and motor, which restores the required velocity without changing the casing, the flow or the pump. The water still has to come from somewhere, so the sleeve is fitted with a short tail that guides it in from above.

Situation	Signs you need a flow sleeve	What it changes
Casing ID more than about 50 mm larger than the motor outside diameter	Free convection no longer applies per published guidance	Restores the annulus velocity to the value in the tables
Computed velocity below the floor for the motor size	v below 0.08 m/s for a 4-inch motor, or below 0.15 m/s for 6-inch and larger	Same, and lets you keep a pump you already own
Pump already showing thermal trips on hot afternoons	Controller derating, thermal protection tripping, output falling after midday	Cuts winding temperature and stops the derating
Well produces sand	Sand settles around a bare motor and insulates it	Also shields the motor from abrasion, which is why makers of sand-handling pumps fit them as standard
Pump installed in an oversized casing in a horizontal or inclined position	Free convection does not work horizontally, so forced flow is mandatory	Makes a horizontal installation possible at all
Casing much wider than the motor and the pump runs near its minimum flow	The worst case: wide annulus plus low flow plus high ambient water temperature	The only fix short of changing the borehole

The economics are lopsided in your favour. A sleeve is a short length of pipe of the next size up, a pair of end caps and a couple of hours of workshop time. The alternative is a motor that runs hot for two or three seasons and then fails in a year you will remember, or re-drilling a borehole. The published guidance is explicit that where the annulus is wide, a sleeve or inducer must be used rather than being an optional refinement.

Two cautions. A sleeve reduces the effective clearance between the assembly and the casing, so you must re-check the fit with the sleeve fitted, not with the bare pump. And a sleeve must not block the pump intake: it goes over the motor, with the intake above it, not over the intake itself.

The trap when you re-equip an inherited borehole

The worst casing-to-pump mismatches are almost never the result of a new drilling decision. They are inherited. Somebody else’s hole, drilled for somebody else’s equipment, twenty or thirty years ago.

Four patterns account for most of them, and all four look generous on paper:

What you inherited	Why it looks good	What actually goes wrong
A wide hole drilled for a lineshaft turbine, 10 to 14 inches	Plenty of room, nothing can jam	A 4-inch submersible in a 12-inch hole needs about 19 m3/h to cool itself, and will never make it
A hole that was reamed for a larger pump and then partly lined	The top of the casing is wide	The casing joint or the liner reduces the bore partway down, which is where the pump stops
An old steel casing with scale, corrosion or ovality	Nominal diameter is fine on the driller’s log	The effective bore is smaller than nominal, and no longer round, so the pump passes at the top and jams lower
A hole converted from a different duty, for example an abandoned irrigation well	Water is available and the head looks modest	The casing size was chosen for flow, not for the temperature of a motor that will now run all day

The pattern in the first row is the one to watch. A wide hole is a real liability for a small pump, and the cost of dealing with it is either a flow sleeve or a drilling contractor. A sleeve is dramatically cheaper, and on a well that has been sitting idle it is usually the right first move rather than a last resort.

Alongside the casing size, two more inherited numbers matter and are usually not on the paperwork. The temperature of the water down there decides how much cooling margin you have, because a motor rated for 30 degrees Celsius is not the same motor at 40 degrees, and published derating curves step down noticeably above 30 degrees. And the sand content decides how fast the whole assembly wears, with well-construction guidance commonly calling for finished wells under 25 mg/L. Both are cheap to test, and both change the pump you should buy rather than the pump you can fit.

Worked example: one pump, five casing sizes

Take a real 4-inch model, 4DSC7.5-80-110-1300: 1300 W, 110 V, 7.5 m3/h maximum flow, 80 m maximum head, 2-inch outlet. Put it in a well where it has to produce around 6 m3/h at about 47 m of total head, which is a comfortable operating point for this model rather than a brave one. Then change nothing but the casing.

Casing ID	Radial gap	Velocity at 6 m3/h	Flow needed for 0.08 m/s	Verdict
4 inch (102 mm)	3.5 mm	1.536 m/s	0.31 m3/h	Will not pass with cable and rope attached
5 inch (127 mm)	16.0 mm	0.298 m/s	1.61 m3/h	Fine, velocity nearly 4x the floor
6 inch (152 mm)	28.5 mm	0.150 m/s	3.19 m3/h	Fine, velocity at 1.9x the floor
7 inch (178 mm)	41.5 mm	0.093 m/s	5.14 m3/h	Fine, but only 16% above the floor
8 inch (203 mm)	54.0 mm	0.066 m/s	7.29 m3/h	Below the floor: 82% of required. Sleeve needed
10 inch (254 mm)	79.5 mm	0.038 m/s	12.58 m3/h	48% of required. Sleeve mandatory
12 inch (305 mm)	105.0 mm	0.025 m/s	19.04 m3/h	32% of required. Sleeve mandatory

Seven rows, one pump, one flow, one head. The pump is identical in every row. The only variable is a number that was decided by a driller before anyone thought about a pump, and it decides whether this installation works quietly or fails in its third summer.

Two further details from the same example, because they cost nothing to check now and a lot later. Water is lifted from a depressed level, so the pump runs at 47 m of total head whenever it is at 6 m3/h, which means the model above is operating at about 59% of its maximum head and therefore well inside its curve rather than at its end. And the panel array follows the catalogue rule of 1.3 times pump power minimum, so 1300 W wants at least 1690 W of array, with the string open-circuit voltage kept below the controller limit for the 110 V family. The cable sizing guide is the next thing to check, because the same annulus that makes the pump tight also determines how thick a cable you can get down there, and voltage drop on a deep set is what quietly steals your flow.

Matching the Trista range to the casing you already own

Our catalogue is organised by body diameter, which means the series name already tells you the casing size you need. This is deliberately the first thing to look at, before power, before head and before price:

Body diameter	Series	Flow range in the catalogue	Typical casing needed	Example real models
2 inch	2DPC	1.5 to 1.7 m3/h	3 inch or larger	2DPC1.5-35-24-200, 2DPC1.7-64-48-400
3 inch	3DPC, 3DSC, 3DSS	0.5 to 7.5 m3/h	4 inch or larger	3DSC4.5-50-48-400, 3DSC4.8-95-48-750, 3DSC5-112-110-1100, 3DSC6-115-110-1500
4 inch	4DPC, 4DSC, 4DLR, 4DFS, 4HJSC	3.5 to 27 m3/h	5 inch minimum, 6 inch preferred above about 9 m3/h	4DSC3.5-86-48-600, 4DSC6-101-110-1100, 4DSC7.5-100-110-1500, 4DSC9.5-90-110-1500, 4DSC15-45-110-750, 4DSC20-48-110-1500, 4DSC25-26-110-1500
4 inch or 6 inch	4/6DSC	30 to 95 m3/h	Confirm the model outside diameter before ordering	4/6DSC30-19-110-1100, 4/6DSC30-31-110-1500, 4/6DSC36-22-110-1500, 4/6DSC46-51-380/520-3000-A/D, 4/6DSC65-42-380/520-4000-A/D
6 inch	6DSC	36 to 130 m3/h	8 inch or larger	6DSC36-108-380/520-5500-A/D, 6DSC46-86-380/520-5500-A/D, 6DSC65-63-380/520-5500-A/D, 6DSC95-66-380/520-7500-A/D, 6DSC130-75-380/520-15000-A/D
8 inch	8DSC	150 m3/h	10 inch or larger	8DSC150-37-380/520-11000-A/D

A note on the 6DSC and 8DSC lines: the body diameter sets the casing, and the casing does not scale kindly. A 6-inch pump needs an 8-inch casing. If your borehole is 6 inches, the largest submersible that fits comfortably is a 4-inch model, and that is why the 4/6DSC and 4DSC lines carry so much of the flow range between 3.5 and 30 m3/h. Anyone who has a 6-inch hole and wants 40 m3/h has a drilling problem, not a pump problem.

A strong illustration of how much casing size matters at the high-flow end comes from a measured curve we publish for 4/6DSC30-19-72-1100, one of the models with a real single-model test curve rather than a shared series curve:

Total head	Flow
0.50 m	0.5 m3/h
7.53 m	5.01 m3/h
13.46 m	9.05 m3/h
15.80 m	14.27 m3/h
17.03 m	17.03 m3/h
18.00 m	32.59 m3/h

At its design end this pump moves more than 30 m3/h, which is enough to keep a 4-inch motor cool even in a 12-inch casing. At the far left of the same curve it moves half a cubic metre an hour, which is not enough to cool that motor in anything wider than a 5-inch hole. The model is the same. The operating point moved. This is why the cooling calculation has to be done at your real duty point, not at the pump’s maximum flow.

Once the casing has decided the body diameter, choosing inside that series is an ordinary sizing exercise and the sizing guide and total head calculation take you through it. If the head you need is unusually large for the body diameter you are stuck with, the high-head deep well guide deals with that specific trade, and if the hole is too small for any submersible at all, the honest answer may be a surface pump or an intake arrangement rather than a bigger pump, which the comparison of submersible and surface pumps sets out.

What to measure before you buy anything

Everything above collapses into a short list of measurements and one calculation. Do them in this order, because the earlier ones change the later ones.

Order	What to establish	Why it comes here
1	Casing inside diameter, measured at the well head and again at depth if you can	Sets the maximum body diameter of any pump you can consider
2	The narrowest section of the hole, including any casing joint, screen or repair	The pump has to pass the tightest point, not the average
3	Whether the hole is straight and plumb over the depth the pump will sit	A dog-leg rules out a pump that the diameter alone would allow
4	Pump setting depth and the free passage margin you can live with	The intended depth plus 25% is a good specification to insist on
5	The widest fitting on the assembly, including the non-return valve and the drop pipe coupling	Often wider than the pump, and often forgotten
6	Cable and safety rope thickness as a bundle	Decides whether the ring of clearance you have is real or theoretical
7	Your real duty point: flow at total head	The cooling calculation depends on flow, not on the pump’s rating
8	Compute the annulus velocity with v = Q x 353 / (D² - d²) and compare it with 0.08 m/s for a 4-inch motor or 0.15 m/s for larger	The single check that decides whether you need a flow sleeve

Two habits make all of this cheap. Measure and write down the casing inside diameter before you shortlist a pump, not after the pump arrives. And when a borehole is inherited, overdrawn or more than ten years old, spend the money on a downhole survey before spending it on hardware. A camera run and a plumbness log cost a fraction of a motor, and they answer the question that a datasheet cannot: whether the pump you want will actually reach the water.

If you would rather hand the arithmetic over, send me the casing size, the setting depth, the head and the flow you need and I will come back with the body diameter that fits, the velocity at your duty point, whether you need a sleeve, and a model from the range that matches.

---

Not sure your borehole will accept the pump you want? Put your casing inside diameter, setting depth, flow and total head into the sizing tool and it will check the annulus velocity for you, or message me on WhatsApp with your casing inside diameter, well depth, static water level, flow needed and total head, and I will tell you which body diameter fits, whether the motor will stay cool and which model to order.