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Mistakes when choosing and buying a water pump

Updated: Jul 19, 2023

Last month, we wrote about how to choose the right pump for pumping water and central heating. Based on many years of experience in the production of pumps, opinions and feedback from our customers, the technical specialists of Pentax S.p.A. outlined what mistakes buyers make when choosing pumping equipment. This article will give you general tips for choosing pump equipment and teach you how to avoid common errors.

1. Incorrect pump power.

Wrong energy output is the most common oversight. As a result, users often need more power or might purchase a dubious, underpowered copy. Due to this error, not enough water flows for all use cases. For example, if you notice that the water barely flows when you turn on the washing machine, dishwasher, shower, or tap simultaneously - the pump is most likely underpowered.

The right pump should provide enough pressure and water flow for maximum consumption. In addition, the user should choose approximate power values within 70-80% of the manufacturer's maximum.

But customers sometimes overpay for an oversized, powerful pump in a well with a small depth. In this case, the well will not provide the required water flow due to the wrong choice of pump power and operating conditions.

You can use our guide to choose the right pump to avoid choosing the wrong power.

2. Pumping with seawater or acidic water

This fundamental error results from an incorrect selection of the pump model. For example, you must not use a surface self-priming pump to pump water from a depth of more than 9 meters or try to pump hot water with a temperature higher than that specified in the pump specification (usually >60 °C). These are non-warranty cases, resulting either in dissatisfaction with the technical characteristics of the pump in the first case or the breakdown of the pump as a result of hot water simply damaging the seals.

Household pumps could break if you try to pump chemical fluids, fuels or seawater. In addition, acid and alkali solutions damage pump parts and can cause fire and damage health.

Carefully read your pump's datasheet, especially the safe use section. In addition, our website provides specifications and manuals for each series of Foras water pumps.

3. Pumping with dirty water

The vast majority of surface pumps specialise in pumping clean water. Therefore, only a small number of parties are allowed. The maximum particle size you can find in the datasheet. If you need to pump large particles, you can find specialised pumps like the popular Foras model of the RA-series, with an open impeller that can churn solid particles up to 10 mm in water.

Most household pumps will work if the water comes with small-particled clay or silt. However, murky water will reduce the performance of the pump. If the water contains abrasive particles (such as sand), ensure the particle size does not exceed the pump's specifications. Remember that vortex pumps are more demanding on water purity than centrifugal ones. Note that most borehole pumps are designed for the presence of sand suspension in water with a percentage of 50-150 g/m3

If the pumped water is entirely opaque from dirt and contains large inclusions (more than 2 mm), buying a drain or sewer pump is better. These pumps a for pumping viscous liquids. In addition, many of them are equipped with a small mill (grinder) at the inlet for grinding solids entering the pumping.

4. The pump is turned on-off too often.

Small pumps often need to be designed for continuous operation and frequent switching. These pumps usually have run times and start per hour listed in their specifications. If this time is exceeded, the pump will overheat and shut down due to the tripping of the thermal fuse (if present).

If users need to pump large quantities of water, they should look for professional pumps and avoid pumps with limited run time. All Foras pumps are for long-term professional use, unlike many other manufacturers.

Pumps with a limited number of starts per hour should be combined with sufficient-size accumulators and carefully considered for use in pumping stations without accumulators. With the small size of the accumulator, the station can turn on the pump several times a minute. Therefore, economy-class pumps with a limit of 20 starts per hour could break.

5. The hydraulic resistance is too high

When selecting a pump, it is essential to consider the hydraulic resistance of the pipes. Here is an example from one of our clients:

" Mark's submersible sump pump burned out, and he bought a pump with a higher motor capacity. The situation repeated itself. Mark went to our specialists, who found out that Mark installed the hose with a diameter of 19 mm and a length of 25 m at the outlet of the pump. The pump's capacity was 10 m3/hour with a height maximum of 8 m. According to calculations, the hydraulic resistance of such a pipe at such a flow rate is 30 m. Accordingly, the pump constantly worked with overload. Because of this, it overheated its motor and short-circuited the windings. Thanks to the recommendations, Mark installed a larger diameter pressure hose, and his Foras submersible pump has been working without any problems for five years now."

6. Automatic protection is not installed

Using a water pump without protection and automation devices often results in parts failure and breakdowns. For example, in most wells, water flows very slowly, and a pump with an average capacity of 1.5 m3 / h can pump out all the water in 1–2 hours. If a floating shut-off switch is absent, a drop in the water level can lead to the pump running dry. As a result, the pump overheats the mechanical seal and the motor, resulting in pump failure and damage. Each overheating eventually leads to destructive changes in the stator insulation, ultimately leading to a short circuit in the winding.

If you do need automatic switching, consider purchasing a pressure switch.

Users can also face problems if they use a submersible sewage pump with a macerator without an automatic motor protection switch. If a solid object gets under the chopper knife, the pump jams. And, if there is no circuit breaker, the pump overheats and burns out its motor windings.

If you want your pump to work correctly and for a long time, you must protect it and choose the right accessories.

7. Lack of available servicing and spare parts.

When buying, be sure to check with the seller for the availability of spare parts for water pumps. This indicates the company's professionalism and that you can permanently repair your equipment.

In the catalogue of spare parts on our site, you can find parts for all models of the brand Foras, Pentax and Marley.

8. Pumps are untested

The price of a pump is only sometimes a guarantee of quality. However, it is worth noting that Foras water pumps, for example, are high-quality products at affordable prices. An elaborate testing process assures the quality of each electric pump. Foras tests both the mechanical and electrical parts of each pump twice. Only some manufacturers perform this rigorous testing, let alone cheap alternatives.

Some manufacturers use plastic for many pumping equipment parts, as it keeps costs down. However, plastic is inferior to metals and alloys in strength and durability.

Foras manufactures its pumps in stainless steel or cast iron, which makes them more durable and reduces operating noise.

Thanks to continuous research and testing, Foras' wide range of water pumps will satisfy the needs of every customer.


In conclusion, understanding the mechanics of your water pump for your house is crucial. Whether it's a submersible pump or a jet pump, including the deep well jet pump, the right choice can significantly impact the efficiency of your water pump in-house. A common mistake to avoid is the incorrect choice of pump power - either overestimating or underestimating it can lead to issues in your water flow.

It's also important to consider the type of water your pump will handle. Not all pumps can manage seawater, acidic water or dirty water. Thus, understanding the specifics of your electric water pump installation is essential.

The house water pump should be chosen based on the water source and the home's requirements. For instance, a small water pump may not be the best option for a large household with high water consumption.

Moreover, the pressure switch and the pressure tank play significant roles in maintaining constant water pressure. The pressure tank stores water under pressure for delivery when needed, while the pressure switch signals the pump to start or stop pumping based on the water pressure.

The well pump plays a significant role in drawing water from wells for household use. The right well pump can ensure a steady water supply and prevent water shortage.

In essence, careful selection and understanding of your water pump at home can save you from unnecessary troubles and costs. Always ensure your pump suits the specific conditions of your water pump domestic system, considering factors like water type, power requirement, and water pressure. Doing so can ensure a smooth and efficient water supply in your home.


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