How to choose a water pump: petrol, submersible or drainage?

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How to choose a water pump: gasoline, submersible or drainage?

Selecting the right water pump is one of those decisions where a cheap or rushed solution can cost more than double the original investment – a non-functional pump in the wrong application will either break down quickly or simply won't do the job you bought it for. Dozens of customers ask the same question every year: "Should I buy a gasoline, submersible or drainage pump?" And the answer is never one-size-fits-all – it depends on where you are taking the water from, where you want to deliver it to, in what environment you will be using the pump and how clean the pumped liquid is.

In this article, we will cover all three main types of water pumps, their technical parameters, typical uses, strengths and limitations. You will get concrete numbers, practical examples from real customer cases and clear comparisons to help you choose exactly what will truly solve your problem.

Basic classification of water pumps

Before we dive into the details of each type, it's important to understand the basic logic according to which pumps are divided. There are three main criteria:

Power source: electric motor (230 V or 400 V) or gasoline/diesel internal combustion engine
Pump placement: surface-mounted (the pump stands above the water level) or submersible (the entire pump is below the water level)
Type of pumped liquid: clean water, utility water with mechanical impurities, or sludge, mud, sewage

These three criteria overlap and form the basis for selecting the right machine. Let's go through each type in detail.

Gasoline water pump – when and why to choose it

A gasoline pump is primarily about independence from the electrical grid. This is its biggest advantage and also the most common reason for purchase. If you are working on a construction site without a connection, at a remote cottage, in a garden where there is no extension cable of sufficient thickness available, or need to react quickly to an emergency or flood anywhere – a gasoline pump is the clear choice.

These machines are designed as surface-mounted self-priming pumps. This means that the pump stands on dry ground (or on a stable surface) and draws water using a suction hose that you lower into a well, water supply, pond, stream or flooded area. The suction reach of standard models is 7 to 9 meters in depth – this is physically determined by atmospheric pressure and does not depend on the motor power.

Technical parameters of gasoline pumps – what the numbers mean

When comparing gasoline pumps, you will encounter several key parameters:

Discharge head (m): the maximum vertical distance to which the pump can pump water. Note – at maximum discharge, the flow is almost zero. Real operation is at 60–70 % of maximum discharge.
Flow rate (l/min or m³/h): the amount of water transferred per unit of time at zero back pressure. The longer and narrower the hose and the greater the discharge, the lower the actual flow rate.
Motor power (W or kW or HP): the power of the combustion engine. A more powerful engine = greater possible discharge and flow, but also higher fuel consumption and machine weight.
Tank capacity (l): determines the autonomy of the machine – how long it will run without refueling.

Let's look at specific models from our range. Gasoline pump BZP-10 is a basic, compact and easily portable model suitable for garden use – irrigation, filling a swimming pool, pumping water from drainage ditches or from minor flooding. It is a machine for occasional use, where you don't need extreme discharge or high flow, but you appreciate its lightness and ease of operation.

For more demanding garden and construction applications, the BZP-20 is suitable – a motor-driven self-priming pump for clean and utility water. This model can also handle water with fine mechanical impurities, which makes it suitable for situations where the water is not completely clear – for example, when pumping from surface sources, from catch basins after rain or for rough water removal from a construction site.

If you need significantly higher performance and longer discharge, look at the BZP-30 with a power of 4,850 W, a discharge of 30 m, and a 3.6-liter tank, powered by a four-stroke engine. A four-stroke engine has an important advantage over a two-stroke engine: it runs on clean gasoline without mixing with oil, is more economical, quieter, and has a longer lifespan. The BZP-30 model can, for example, supply water from a surface source to a large garden reservoir, pump water from a pond during a fire in the field, or ensure water supply at a construction site.

The H-BZP-30 is intended for professional and industrial use – power 9,690 W, maximum discharge up to 95 meters, four-stroke engine. This is a machine for truly demanding tasks: long-distance water routing over terrain with elevation, firefighting purposes, intensive construction work, or supplying remote locations. A discharge of 95 m in practice means you can pump water to the height of the ninth floor or along a horizontal route of several hundred meters (where 1 m in height ≈ 10 m in horizontal distance from the perspective of hydraulic resistance).

When a gasoline pump is not the right choice

Gasoline pumps also have their limits that you should know before purchasing:

They cannot be operated in enclosed spaces – exhaust gases contain carbon monoxide and are deadly in a basement, garage, or warehouse without ventilation. This is not a recommendation, it is an absolute prohibition.
Noise – gasoline engines typically produce 70–90 dB(A), which is problematic during night hours or in residential areas.
Regular maintenance – oil must be changed according to operating time (typically every 25–50 engine hours), spark plugs, air filter, carburetor.
They are not suitable for continuous water supply – if you need water every day throughout the year, an electric solution will be cheaper and more convenient.
They do not pump sludge and mud – standard gasoline pumps are designed for clean or utility water. For sludge, a sludge pump is required.

More about the advantages and disadvantages of gasoline pumps compared to electric ones can be found in the article Gasoline water pump: what it is suitable for and when it is worth it compared to an electric one.

Submersible pump – water supply from a well or borehole

A submersible pump is a fundamentally different solution. The entire machine – motor and hydraulic part – is submerged below the water level and operates directly at the source. Water is not pumped up from the air (where the limitation of suction range of 7–9 m would apply), but is pushed up from the pump itself. This is a key difference, which allows a submersible pump to supply water from wells and boreholes of 20, 50, 80 meters or more in depth.

The submersible pump SKM 100 is a classic representative of this category – a slim cylindrical machine designed directly into the well or borehole. It operates on 230 V, is quiet (the motor is cooled by the surrounding water, so you can hardly hear anything from it), and is capable of supplying a household, garden, or farm with water from a greater depth. It usually works in combination with a pressure tank and an automatic pressure switch – thus creating a home water supply system that operates automatically without your presence.

How to choose a submersible pump: diameter, depth, flow rate

When choosing a submersible pump, you must know these parameters of your well or borehole:

Inner diameter of the well or borehole: Most slim submersible pumps have a diameter of 4" (about 102 mm) or 3" (about 76 mm). Older boreholes may have a diameter of 4" or 6". If your borehole has a diameter of 4", you cannot fit a pump with an outer diameter greater than about 96 mm. Always check the diameter of the borehole in the documentation or with the driller.
Depth of the water level: this is not the depth of the borehole, but the depth at which the stable water level moves. The pump must be submerged at least 1–2 m below this level to avoid pumping air.
Well yield (l/hour): how much water flows into the well naturally per hour. The pump must not pump faster than the well can replenish the water – otherwise you will drain it dry and the pump will run dry, which will damage it.
Required discharge: the sum of the depth of the pump below ground and the height to which the water needs to be delivered above the surface (e.g., to a roof tank or a water storage tank).

A detailed guide on how to calculate the required discharge can be found in the article Discharge and pump power: how to calculate what you need for a garden or well. If you are directly dimensioning for a well or borehole, the article Submersible pump for a well or borehole: which diameter and depth suits which pump will help you.

Advantages and disadvantages of a submersible pump

Advantages:

Can pump from great depths (20–100+ meters)
Quiet operation – the motor is under water, noise is minimal
Automatic operation with pressure switch and tank
Does not require regular monitoring during operation
The motor is cooled by surrounding water – it does not overheat during long operation

Disadvantages:

Requires an electrical connection (230 V or 400 V)
Installation into a well is more demanding and requires expertise
In case of failure, the pump must be pulled out of the well – which can be costly
Not portable – it is permanently installed
Pumps only clean water – for mud or sludge, special slurry types are used

Step-by-step installation of a submersible pump can be found in the article Installation of a submersible pump into a well or borehole: step-by-step guide.

Drainage and slurry pump – for drainage, floods and mud

A drainage pump is a special category of submersible pumps, designed for a completely different purpose: not for supplying water from a source, but for removing unwanted water from spaces or terrain. Typical applications include:

Draining water from a basement or cellar after flooding
Draining a construction pit or excavation
Emptying a swimming pool or garden tank
Removing rainwater from garden depressions
Pumping mud and sludge (slurry pumps – a more robust variant)
Draining irrigation ditches

The key technical difference between a drainage pump and a standard submersible pump is in the design of the hydraulic part. Drainage pumps have larger openings in the impeller and inlet to prevent clogging by solid particles. Standard drainage pumps can handle solid particles up to 5–10 mm, while slurry types can handle up to 25–35 mm. In addition, many drainage pumps can pump water from a level only a few millimeters above the bottom – something standard submersible well pumps cannot do.

How to tell if you need a drainage or slurry pump

There is a simple practical test: if you immerse your hand into a bucket with a sample of your water and after pulling it out your hand is only wet (the water is murky but clear and without coarse sediments), a standard drainage pump will suffice. If the bucket is full of mud, where the bottom is not visible and there are sand and stone particles at the bottom, you need a slurry pump with a stronger hydraulic system and a more robust construction.

More on this topic can be found in the article Water pump for clean water vs. slurry drainage pump: what is the difference and when to use which.

Practical scenarios from everyday customer practice

The best decisions are made in concrete cases. Here are a few typical situations we encounter during consultations with customers:

Scenario 1: Gardener with an 8-meter slope and a garden well

The customer has a masonry well 6 m deep, with the water level 3 m below the surface. He wants to irrigate the garden on the slope – the garden is 8 m above the well. He has an extension cord on the surface. The required head is 3 m (depth of water level) + 8 m (elevation) + losses in the pipe ≈ 13–14 m total head. A standard submersible pump with a head of 20+ m will suffice here, or alternatively a surface electric pump. A gasoline pump is not necessary here, but if the customer does gardening work far from an outlet, he may opt for a light gasoline pump BZP-10 for the convenience of transport.

Scenario 2: Construction of a family house – excavation drainage after rain

Classic situation on a construction site: after a night of rain, there is standing water up to knee height in an excavation 1.5 m deep, with mud mixed in the ground. The electrical connection is not yet installed. Solution: gasoline pump with a suction basket and suction pipe – ideally BZP-20 or BZP-30 depending on the excavation volume. If the water is heavily contaminated with mud, a slurry drainage pump powered by gasoline is needed or an electric slurry pump with a generator available. Time to drain an excavation of 10 m² to a depth of 0.5 m (approx. 5,000 liters) at a flow rate of 500 l/min is less than 10 minutes.

Scenario 3: Mountain cabin without electricity – water supply from a mountain spring

The customer has a cabin at 800 m above sea level, where there is no electricity. A stream or spring flows nearby at a distance of 30 m and 12 m lower. They want to transport water to a storage tank at the cabin. Vertical lift 12 m + horizontal route 30 m (≈ 3 m hydraulic losses) = approx. 15–18 m of required lift. Here, a gasoline pump is an ideal solution – BZP-20 or BZP-30 can easily handle it. The pump is started once every few days to fill the tank – fuel consumption is minimal.

Scenario 4: Flooded basement during heavy rain

A very common problem in older houses without an insulated basement. The basement is flooded with 40 cm of water, the total area is 30 m² – that is 12,000 liters of water. The water is not muddy, just dirty. Solution: an electric drainage pump submerged in the basement, a lift of 5–8 m is sufficient (just to the height of a window or door outside the basement). Drainage time at a flow rate of 150–200 l/min is less than an hour. Here, a gasoline pump is not an option – the basement is an enclosed space and exhaust gases would be lethal.

Scenario 5: Deep 60 m well for a family house

The customer had a well drilled to a depth of 60 m, the water level is stable at 40 m. The house is at ground level. Required lift = 40 m (depth of the water level) + 15 m (building height and distribution) + losses ≈ 60–65 m. A submersible pump with a lift of at least 70–80 m is needed for reserve, with a diameter suitable for a 4" well. A gasoline pump with a maximum suction range of 9 m is absolutely unsuitable – physically it is not able to suck water from such a depth.

Technical parameters – what to compare when choosing

For clarity, we present a summary comparison of the main parameters according to pump type:

Parameter	Gasoline	Submersible (well/borehole)	Drainage/slurry
Drive	Gasoline engine	230 V / 400 V	230 V
Suction range (max.)	7–9 m	Not limited (it pushes)	Not limited (submersible)
Max. lift	20–95 m	30–150+ m	5–20 m
Portability	Yes – fully portable	No – permanently installed	Yes – portable
Need for electrical connection	No	Yes	Yes
Type of liquid pumped	Clean / utility water	Clean water	Contaminated / slurry
Operation in enclosed space	NO – dangerous	Yes	Yes
Automatic operation	No – started manually	Yes – with pressure switch	Yes – with float switch
Purchase price	Medium – higher	Medium	Lower – medium
Operating costs	Higher (fuel, oil)	Low (electricity)	Low (electricity)

Safety and responsible operation of pumps

When working with pumps, there are several safety rules that must always be followed – without exception:

Gasoline pumps are never used in enclosed spaces: Carbon monoxide (CO) is colorless, odorless, and deadly. Even a short start in a basement, garage, or tent is not safe. Always outdoors, always with access to fresh air.
Electric pumps and water: All electric pumps must have the required IP protection rating (at least IP68 for submersible). Cable connections must be outside the water and in a dry environment.
Dry operation: Most pumps are damaged when operated without water – the impeller can overheat and melt. Always check that the pump is submerged or that the suction line is filled with water before starting.
Correct hose sizing: The suction hose must have a sufficient diameter – too narrow a hose increases hydraulic resistance and reduces the actual performance of the pump. Most gasoline pumps have a 1.5" or 2" inlet.
Winterization: Every pump that remains outdoors in freezing weather must be drained and dried before winter. Frozen water in the hydraulic part causes cracks and irreversible damage. Details can be found in the article Maintenance and winterization of pumps: how to extend the life of gasoline and submersible pumps.

Accessories and add-ons you should not forget

The pump itself is only the core of the system. To ensure reliable operation, you will likely also need:

Suction basket with check valve: Fitted to the end of the suction pipe, it prevents large impurities from entering the pump and keeps water in the suction line when the pump is turned off – the pump then does not need to refill the suction system. A suction basket is an absolute necessity for gasoline pumps.
Suction hose: Must be rigid (armored), so that the vacuum does not collapse or close it. Ordinary garden hoses are not sufficient for the suction circuit.
Discharge hose or rigid pipe: For discharge, you can use a standard garden hose or PE pipe depending on the length and route.
Pressure tank (expansion vessel): In a home water supply with submersible pumps, the tank is essential – it prevents short cycling (the pump would turn on with every tap opening and would quickly wear out).
Pressure switch: Automatically starts and stops the pump according to the set pressure in the system.
Float switch: In drainage pumps, it automatically turns off the pump when the water level drops below the set level – protection against dry running.

For the installation of a gasoline pump including the suction basket and the first start-up, read the article Installation of a Gasoline Pump: Connection, Suction Basket, and First Start-up.

Most Common Mistakes When Choosing a Pump

From practice, we know that customers most often make these mistakes when choosing:

They buy a gasoline pump for supply from a 40-meter well – it does not work physically, suction range max. 9 m.
They use a standard submersible pump for pumping mud from a construction site – it clogs and burns out the winding.
They forget about the real head – they buy a pump with a max. head of 20 m, but their application requires a real 15 m, while at 15 m head, the machine delivers only 20 l/min instead of the catalog 200 l/min at zero head.
They underestimate the well yield – they buy a powerful pump that drains the well in 10 minutes and then wait an hour for it to refill.
They start a gasoline pump in a basement – the most dangerous and unfortunately not a rare mistake.

If you are unsure about the calculation, we recommend reading the article Head and Pump Performance: How to Calculate What You Need for a Garden or Well – you will find specific formulas and examples there.

Most Frequently Asked Questions (FAQ)

Can I use a gasoline pump to pump water from a 15 m deep well?

No, unfortunately it is not physically possible. Every surface (self-priming) pump – regardless of motor power – can suck water from a maximum depth of 7 to 9 meters. This value is determined by atmospheric pressure and cannot be overcome by any pump power. For a depth of 15 m, you must use a submersible pump, which is placed directly under the water surface and pushes the water upward.

Can a gasoline pump be used to pump water out of a basement?

Absolutely not. A gasoline pump produces exhaust gases containing carbon monoxide (CO), which is deadly in enclosed spaces. Always use an electric sump pump with an extension cord for pumping water from a basement or cellar. A gasoline pump can be placed outside the entrance to the basement, but even then, you must ensure that the exhaust is not directed into an open entrance.

What is the difference between a sump pump and a sewage pump?

A sump pump is designed for pumping relatively clean or slightly contaminated water – it can handle solid particles up to about 5–10 mm in size. A sewage pump has a more robust and larger hydraulic system with larger passages, which can handle thicker sludge, sediment, and solid particles up to 25–35 mm. Sewage pumps are heavier and more expensive, but without them, a regular sump pump would quickly clog or burn out in sludgy water. If you are unsure, read the article Clean Water Pump vs. Sewage Sump Pump: What is the Difference and When to Use Each.

Do I need a pressure tank for a submersible pump in a well?

For home water supply, almost always yes. Without a pressure tank (expansion vessel), the pump would start every time a tap is opened – even if only slightly.

Do you have a question about this topic?

Can't decide or are you dealing with a specific situation in your household? Write to us – we are happy to help.