Water Pump Buying Checklist
The wrong pump is almost never a brand mistake. It is a duty mistake: too little head, too small a pipe, or a surge the power source cannot start. This checklist fixes the numbers before the box arrives.
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Define the duty first
Write down the job in plain numbers before you look at a single pump.
- COREThe source named: bore, well, rain tank, dam, river or municipal boost Amazon
- COREWhat the pump must feed: house taps, garden, stock troughs or irrigation Amazon
- How often it runs: constant, timed, on-demand or tank-topping Amazon
- COREThe power actually available at the pump: mains, solar, battery or generator Amazon
Measure total dynamic head and flow
Head is the height and friction the pump must overcome. It is the number that decides success.
- COREStatic lift: the vertical distance from water level to the highest delivery point Amazon
- Friction head: the pipe length, diameter and bends converted to an equivalent lift Amazon
- CORERequired flow in litres per minute at the far end, not at the pump outlet Amazon
- A total dynamic head figure: static plus friction plus the pressure head you need Amazon
Match the pump type to the source
The source and the duty pick the machine; the catalogue only confirms it.
- CORESubmersible bore pump for deep, narrow sources where a surface pump cannot suck Amazon
- Jet or peripheral surface pump for shallow tanks and low-lift transfer Amazon
- COREPressure pump with a tank for feeding a house at steady mains-like pressure Amazon
- Solar or hand pump where grid power is absent or must be backed up Amazon
Size the power and starting surge
A pump is rated for running watts and, often hidden, for a much larger starting spike.
- CORERunning watts confirmed from the plate, and the starting surge found in the spec sheet Amazon
- COREInverter or generator rated for the surge, not just the continuous draw Amazon
- Soft-start or constant-speed drive considered to cut the spike on repeated starts Amazon
- Cable gauge to the pump sized for voltage drop over a long run Amazon
Choose the pressure tank and controls
A pump without a tank or control strategy cycles to death in a year.
- COREA pressure tank sized to hold enough water to stop short-cycling on small draws Amazon
- A pressure switch set to sensible cut-in and cut-out for the duty Amazon
- COREDry-run protection or a level cut-out so the pump cannot burn out in an empty source Amazon
- Non-return and isolation valves so the system holds prime and can be serviced Amazon
Check materials and suitability
The water and the duty decide what the pump must be made of.
- COREWetted parts rated for the water: potable-safe, food-grade or stainless where drunk Amazon
- Seal and impeller material suited to any sand, grit or salinity in the source Amazon
- Insulation and ingress rating matched to a wet, buried or outdoor installation Amazon
- Spares availability: seals, impellers and control boards stocked for the model Amazon
Buy and install the right way
A correct pump still fails if it is installed against the basics.
- CORESuction and delivery pipe sized to the pump ports, never reduced to save money Amazon
- A foot valve and priming point fitted so a surface pump keeps its prime Amazon
- Warranty and duty coverage read before purchase, especially for bore depth Amazon
- COREService access left at the pump and tank so maintenance is possible later Amazon
A water pump is the part of a system people buy on instinct and regret on the first dry day. The shelf offers wattage and price, and both are the wrong place to start. The right pump is chosen from the job it has to do. That means the source, the height, the distance, the flow and the pressure at the other end.
Get those numbers down and the range collapses fast. A bore needs a slim submersible that fits the casing. A tank needs a pressure pump or a simple transfer pump. A long garden run needs flow. A house needs pressure. Each duty points to a different machine, and each has a right size within it.
The most common purchase errors are head and surge. A pump rated for more flow than height will stall halfway up a hill. A pump that pulls a big starting spike will trip a small inverter or a generator that was sized only for running watts. Both are solvable on paper before you pay.
This checklist runs the buying decision in order. It defines the duty, works out total dynamic head and flow, then chooses the pump type. After that it sizes power and surge, adds a pressure tank and controls, checks materials and warranty, and finishes with the purchase and install details. For keeping a pump alive once you own it see our water pump maintenance checklist. Every buyable line links to current options on Amazon.com, and Spare Theory may earn a commission on those links. We never set or verify Amazon's prices.
At a glance
- Total dynamic head, not the nameplate wattage, decides whether a pump can actually reach your taps.
- A pump bought for a bore is a different machine from one bought for a tank. The source sets the type.
- Starting surge is where a good pump meets a weak power source. Size for the spike, not the run.
- Oversizing a pump costs you money, energy and short-cycling. The right pump is the smallest one that meets the duty.
The full list
The same list the builder above ticks. Use it for printing or when JavaScript is off.
Define the duty first
Write down the job in plain numbers before you look at a single pump.
- COREThe source named: bore, well, rain tank, dam, river or municipal boost Amazon
- COREWhat the pump must feed: house taps, garden, stock troughs or irrigation Amazon
- How often it runs: constant, timed, on-demand or tank-topping Amazon
- COREThe power actually available at the pump: mains, solar, battery or generator Amazon
Measure total dynamic head and flow
Head is the height and friction the pump must overcome. It is the number that decides success.
- COREStatic lift: the vertical distance from water level to the highest delivery point Amazon
- Friction head: the pipe length, diameter and bends converted to an equivalent lift Amazon
- CORERequired flow in litres per minute at the far end, not at the pump outlet Amazon
- A total dynamic head figure: static plus friction plus the pressure head you need Amazon
Match the pump type to the source
The source and the duty pick the machine; the catalogue only confirms it.
- CORESubmersible bore pump for deep, narrow sources where a surface pump cannot suck Amazon
- Jet or peripheral surface pump for shallow tanks and low-lift transfer Amazon
- COREPressure pump with a tank for feeding a house at steady mains-like pressure Amazon
- Solar or hand pump where grid power is absent or must be backed up Amazon
Size the power and starting surge
A pump is rated for running watts and, often hidden, for a much larger starting spike.
- CORERunning watts confirmed from the plate, and the starting surge found in the spec sheet Amazon
- COREInverter or generator rated for the surge, not just the continuous draw Amazon
- Soft-start or constant-speed drive considered to cut the spike on repeated starts Amazon
- Cable gauge to the pump sized for voltage drop over a long run Amazon
Choose the pressure tank and controls
A pump without a tank or control strategy cycles to death in a year.
- COREA pressure tank sized to hold enough water to stop short-cycling on small draws Amazon
- A pressure switch set to sensible cut-in and cut-out for the duty Amazon
- COREDry-run protection or a level cut-out so the pump cannot burn out in an empty source Amazon
- Non-return and isolation valves so the system holds prime and can be serviced Amazon
Check materials and suitability
The water and the duty decide what the pump must be made of.
- COREWetted parts rated for the water: potable-safe, food-grade or stainless where drunk Amazon
- Seal and impeller material suited to any sand, grit or salinity in the source Amazon
- Insulation and ingress rating matched to a wet, buried or outdoor installation Amazon
- Spares availability: seals, impellers and control boards stocked for the model Amazon
Buy and install the right way
A correct pump still fails if it is installed against the basics.
- CORESuction and delivery pipe sized to the pump ports, never reduced to save money Amazon
- A foot valve and priming point fitted so a surface pump keeps its prime Amazon
- Warranty and duty coverage read before purchase, especially for bore depth Amazon
- COREService access left at the pump and tank so maintenance is possible later Amazon
The duty is the shopping list
Most pump regret starts with a missing step. The buyer opens a catalogue before writing down the job. The right first move is a sentence with numbers in it. Name the bore, the taps, the distance, the height, the frequency and the power.
That single duty sentence removes more bad choices than any review. It rules out a surface pump for a deep bore. It rules out a transfer pump for a house that needs pressure. It rules out a mains-only pump for a site that loses power and still needs water.
Once the duty is fixed, the type falls out of it. The source and the use point to a family of pumps, and only then does brand, price and warranty enter. Buying from the duty means the cheapest pump that qualifies is genuinely the right pump.
Write the duty on paper and keep it. It is also the specification you hand any future plumber, and the reference that stops a replacement being bought on a guess.
The review trap: Reviews compare pumps to other pumps, not to your job. A five-star pump for a shallow tank is worthless in a 60-metre bore. Read the duty before the stars.
Start with a duty sentence that has numbers in it. It eliminates the wrong pumps before price ever enters the decision.
Head, not horsepower, is the number that matters
Wattage sells pumps, but head decides them. Total dynamic head is the vertical height plus the friction of the pipe run plus the pressure you want at the end. All of it is converted to metres. It is the honest measure of how hard the pump has to push.
Static lift is easy: measure from the water surface to the highest outlet. Friction head is the sneaky part. A long, narrow pipe with many bends can add the equivalent of many metres of extra height. It quietly turns a comfortable pump into a struggling one.
The consequence of ignoring head is a pump that runs but never reaches. It flows well on a test bucket and stalls at the top of the garden or the second-floor tap. Nothing is broken. The duty was simply never added up.
Do the sum on paper. Add static and friction and required pressure. Buy a pump whose curve delivers the flow you need at that total head, with a little margin. Do not buy one whose headline wattage merely sounds reassuring.
Pipe size is a head decision: Doubling a pipe diameter slashes friction head. A pump that struggles on 20-metre pipe often performs easily on 32-metre. Fixing the pipe is cheaper than upsizing the pump.
Total dynamic head, not watts, decides whether a pump reaches. Add static lift, friction and required pressure, then read the pump curve at that number.
The surge is where a good pump trips a small supply
Electric motors draw a burst of power to start. It is often two to four times their running draw, and lasts a fraction of a second. On mains that is invisible. On an inverter, a battery or a small generator, it is the whole decision.
This is the classic off-grid failure. The pump plate says 400 watts. The inverter is rated 500. Everyone is confident until the pump tries to start and shuts the system down. Running watts matched. Surge watts did not.
Solve it in the right order. Read the starting surge from the datasheet, then size the inverter or generator for that spike, not the run. A pure-sine inverter with proper surge headroom starts most pumps cleanly where a cheap modified-sine unit will buzz and stall.
Where the surge is genuinely large, a soft-start or a constant-speed drive flattens the spike and eases the whole supply. On a solar bore pump, matching the controller to the pump's start current matters as much as matching the panel to its run current.
The nameplate lie: A plate shows running current. It rarely shows the starting spike. Search the full datasheet for locked-rotor or peak watts before trusting the small number.
Size the power source for the starting surge, not the running watts. That gap is the most common way a correct pump still fails to start.
Buy a system, not a pump
A pump alone is a component looking for the rest of a machine. The pressure tank, the switch, the non-return valve, the dry-run protection and the filters are what let it live a full life. They are cheap to include at purchase and expensive to retrofit during a fault.
The pressure tank is not a luxury. Without stored volume, a pump restarts for every cup of water, a fault called short-cycling that kills the motor and the switch within months. Tank size is chosen so the smallest real draw does not trigger a start.
Dry-run protection is the second unmissable part. Pumps are cooled and lubricated by the water they move. A pump running against an empty tank or a dried-up bore destroys itself in minutes. A level cut-out is a small, cheap insurance policy.
So the buy list is a set. Include a correctly sized tank, a pressure switch, non-return and isolation valves, dry-run protection, and a suction filter for dirty water. Price the set, not the pump, and the true cost becomes clear.
The short-cycle tell: If a new system's pump flickers on for any tiny tap draw, the pressure tank is too small or has no pre-charge. Fix it before it damages the motor.
Buy the whole set at once: pump, pressure tank, switch, non-return valve, dry-run protection and filter. The parts prevent the two faults that kill pumps early.
Materials decide whether it survives the water
The pump that touches your drinking water is part of your drinking water. Wetted surfaces must be rated for it. A pump specified for irrigation transfer can leach or corrode when it feeds taps. For potable duty, food-grade materials and appropriate certifications are a hard requirement, not a preference.
The source dictates the rest. Water with sand wears standard impellers quickly and wants a sand-tolerant design. Saline bore water attacks ordinary metals and calls for stainless or matched alloys. A dam with organic load needs a suction filter and easy-clean surfaces.
The environment outside the pump matters too. A buried or permanently wet installation needs a proper ingress rating and sound cable joints. A pump in sunlight needs UV-resistant components. These are spec-sheet lines that decide the service life as surely as the head calculation does.
Before buying, check that wear parts for the model are stocked. A pump with a decade of seals and impellers available is a keepable machine. An obscure model with no parts is disposable the first time it wears.
The spares check: Search the model plus 'seal kit' before you buy. If nothing exists, you are buying a throwaway pump with a warranty you will never claim in time.
Match materials to the water and the site. Use potable-safe parts for drinking, sand- or salt-rated pumps for hard sources, and stocked wear parts so the pump stays repairable.
Right-size down, not up
The instinct is to oversize. A bigger pump feels safe, and it is usually wrong. An oversized pump meets the duty in a fraction of the time it was meant to run. It then sits idle and restarts, short-cycling the motor and wasting energy on every start.
Oversizing also costs twice. First in the purchase and the running watts. Then in the power supply, which must now cover a larger surge, a bigger cable, and a tank sized to tame the extra flow. The pump you 'only paid a little more for' drags a whole chain of cost behind it.
The right pump is the smallest one whose curve comfortably delivers your flow at your total dynamic head. Leave a modest margin for the busy hour. It runs longer, cycles less, starts easier, and draws fewer watts for the same water at the tap.
This is where the sizing calculator earns its keep. It turns the duty and head into a sensible power and flow band. The choice then becomes a number rather than a nervous round-up to the model with the most watts on the box.
The busy-hour rule: Size for the moment several taps run at once, not for every tap open at midnight. A realistic peak, not a theoretical worst case, keeps the pump correctly small.
Buy the smallest pump that meets the duty with a little margin. Oversizing short-cycles the motor, wastes energy and inflates the whole power bill.
Install choices that quietly undo a good buy
A perfectly chosen pump fails on bad pipework more often than on any defect. Reducing a port to fit offcut pipe throttles flow and raises friction. A suction line that leaks air stops a surface pump priming. Both make an excellent pump look useless.
Match the pipe to the pump ports rather than downgrading it. Fit a foot valve and a priming point on the suction so the line stays full. Keep the suction as short and straight as the site allows, because every extra bend is head the pump must pay for.
Leave service access. A pump dropped into a sealed pit is a future problem. With no way to reach the switch, the tank or the filter, nobody can fix it without demolition. Access is free at install and expensive forever after.
Finally, read the warranty conditions before paying. Bore-pump warranties are often written against a depth and a water-quality range. Installing a 'correct' pump outside those stated limits can void the very cover that made it worth buying.
The air-leak test: A surface pump that runs dry after a shut-off has an air leak on the suction side. Paint the joints with soapy water and watch for bubbles drawn inward.
Do not let installation undo the buy. Correct pipe sizes, a foot valve and prime, real service access, and a warranty read before purchase protect the decision.
Pump type by source and duty
| Source / duty | Best pump type | Watch out for | Power note |
|---|---|---|---|
| Deep bore, house supply | Submersible bore pump + tank | Casing diameter and rated depth | Sizing for surge |
| Rain tank to garden | Transfer or jet pump | Low lift only; keep suction short | Small, easy to run |
| Tank to house taps | Pressure pump + pressure tank | Short-cycling if tank undersized | Bigger starting spike |
| Off-grid bore | Solar DC submersible + controller | Controller must cover start current | Panel sized to run watts |
| Backup where grid fails | Battery/inverter or hand pump | Inverter surge headroom | Pure sine recommended |
| Sandy or saline water | Sand-tolerant or stainless pump | Standard impellers wear fast | Same as type |
Confirm every figure against the specific pump's curve and datasheet. Duty, head and surge decide the model far more than brand or headline wattage does.
Key terms
- Total dynamic head
- The full load a pump works against: vertical lift plus pipe friction plus the pressure required at delivery, expressed in metres.
- Static lift
- The vertical distance from the source water surface to the highest delivery point, before friction or pressure is added.
- Starting surge
- The brief burst of extra power an electric motor draws to start, often two to four times its running draw.
- Short-cycling
- A pump switching on and off rapidly on small water draws, usually from an undersized pressure tank, which wears the motor and switch.
- Foot valve
- A one-way valve at the bottom of a suction line that keeps the pipe primed so a surface pump does not lose its water column.
- Dry-run protection
- A control that stops a pump when the source is empty, preventing it from running without the water that cools and lubricates it.
Tips and common mistakes
Field-tested tips
- Write the duty sentence and the total dynamic head figure on a card and carry it when you shop. It turns a browse into a filter.
- Read the pump curve, not just the box. Find the flow the pump actually delivers at your head, which is always less than the free-outlet number.
- Add up the whole set cost before deciding. A cheaper pump with the wrong tank, switch and protection ends up dearer than a correctly bundled system.
- If power is the constraint, size the inverter or generator for surge first and only then pick a pump that fits what is left.
Common mistakes
- Choosing a pump on wattage and price before writing down the source, height, distance and flow it must handle.
- Sizing an inverter or generator to running watts and discovering too late that the starting surge trips it.
- Buying a bare pump with no pressure tank or dry-run protection, then short-cycling it or burning it out in an empty source.
- Upsizing the pump 'to be safe' and paying for it twice through wasted energy, a larger supply and a shorter motor life.
Frequently asked questions
What size water pump do I need for a house?
Work from demand, not rooms. Add up the flow of taps and appliances that might run together. A small home usually needs around 20 to 30 litres per minute. Then find the total dynamic head from the water source to the highest outlet. Choose the smallest pressure pump whose curve meets that flow at that head, paired with a pressure tank large enough to stop short-cycling.
Is a submersible or a surface pump better?
It depends on the source. A submersible pushes water from down inside a bore or deep tank. Beyond roughly seven metres of lift it is the only real choice, because a surface pump physically cannot suck. A surface jet or peripheral pump is cheaper and easier to service for shallow tanks and low-lift transfer. Depth and access decide the type.
Why does my pump trip the inverter when it starts?
The starting surge. Motors draw two to four times their running watts for a moment, and an inverter sized only for running watts will shut down. Check the pump's peak or locked-rotor current, then fit an inverter with genuine surge headroom, ideally pure sine. A soft-start unit flattens the spike if a large pump must run on a modest supply.
Do I really need a pressure tank with my pump?
For a house or any on-demand supply, yes. The tank holds a volume of pressurised water so small draws do not fire the pump, which prevents short-cycling and protects the motor and switch. A garden hose or tank-topping duty with a simple on/off control can run without one, but pressurised household supply cannot sensibly go without it.
Can I run a water pump on solar power?
Yes, and it is common for bore and stock duty. Match a DC submersible pump to a solar controller and to panels sized to the pump's running watts. Then confirm the controller can supply the pump's starting current. Solar pumping suits filling a storage tank during the day, after which gravity feeds the house, rather than direct on-demand pressure without batteries.
Should I oversize a pump to be safe?
Usually no. An oversized pump meets the duty almost instantly, then idles and restarts. That short-cycles the motor and wastes energy on each surge. It also inflates the power supply you must buy. The right choice is the smallest pump whose curve meets your flow at your total dynamic head with a modest margin for the busiest hour.
About this checklist
- Prepared by
- Spare Theory editorial · research-based
- Last checked
- 2026-10-16
How we choose what earns a spotWe build the buying decision around duty, total dynamic head, starting surge and system completeness rather than brand. Sizing guidance follows standard pump-selection practice and manufacturer curve interpretation, and we consistently defer to the specific pump's datasheet for final numbers. We state no prices, endorse no brand, and recommend qualified installation for electrical, bore and potable work.
Reference basisUS Environmental Protection agency and public-health guidance on potable water systemsManufacturer pump-selection and total-dynamic-head engineering references