Booster Pumps

A reverse osmosis membrane can only work if the water is fed to it at a certain pressure. Mains pressure is below that threshold most of the time; on upper floors, on long runs and during peak-use hours it falls noticeably. A booster pump closes that gap. Without a pump the membrane either produces no water at all or runs far below its capacity. Matching the type and the capacity is what decides a pump choice; dry-run protection and fault symptoms are the operating side of the question. You can look at our RO Membranes category for the membrane and our Pressure Tanks category for storage.

Why a Booster Pump Is Needed

Reverse osmosis, as the name says, is the process of reversing the natural osmotic flow. That reversal is only possible with pressure applied from outside. When pressure is insufficient the membrane cannot drive water through the film; the result is production stopping or slowing right down.

In practice a pump solves three problems at once:

• Production rate: A membrane fed at adequate pressure produces close to the capacity it was designed for. The tank fills faster.
• Water quality: As pressure rises, the salt rejection of the membrane improves. At low pressure the quality of the output water drops as well.
• Wastewater ratio: At insufficient pressure the system produces more wastewater. The right pressure brings the ratio back towards the design value of the system.

Pump Types and Capacity

Under-sink domestic pumps

These are compact pumps integrated into standard domestic units. They run quietly, draw little power and are sized to fit under the sink. Under-Sink Purifier Pump 2,941.10 TL.

High-capacity GPD pumps

They are named after membrane capacity and are paired with membranes of the same capacity.

They are preferred in high-capacity under-sink units and in small commercial applications.

Commercial RO pumps

These are defined by hourly flow rate. RO Pump, 600 L/h 19,607.36 TL, built for continuous duty at commercial scale. In this class the pump is chosen according to the total flow rate of the line and the number of membranes.

How to Match a Pump to a Membrane

Pump and membrane are linked choices. The flow rate and the pressure the pump delivers must be compatible with the values the membrane needs.

If the pump is undersized, the membrane cannot reach its design pressure; production falls, the wastewater ratio deteriorates and the output quality stays below what was expected. If the pump is larger than it needs to be, needless strain builds up on the membrane, energy is wasted and the system components tire faster.

Three pieces of data are needed for a correct match: the capacity of the membrane (GPD or L/h), the salinity of the feed water and the existing mains pressure. As salinity rises, the pressure needed for the same production goes up; that is why pump selection for high-salinity sources such as well water differs from mains water.

• 300 GPD membrane → 300 GPD class pump
• 500 GPD membrane → 500 GPD class pump
• Commercial line → RO pump chosen by hourly flow rate
• Industrial line → calculated from the number of membranes and the array layout

Dry Running and Protection

Booster pumps are cooled and lubricated by the water itself. When no water arrives the pump runs empty; this is called dry running and it does permanent damage to the pump within a short time.

The main causes of dry running are these: the mains supply being cut off, the inlet valve being left closed, the pre-filters becoming completely blocked and air being trapped in the feed line. All of them end in no water reaching the pump.

The way to protect against it is to place a low-pressure switch ahead of the pump. This component stops the pump when the inlet pressure falls below a set threshold. The high-pressure switch, which stops the pump once the tank is full, is a standard part of the system too; when that component fails the pump runs continuously, consuming energy and wearing out early.

Pump Faults: Symptom and Cause

Points to Watch During Pump Installation

• Follow the flow direction. The arrow on the pump body shows the direction the water passes. Fitting it the wrong way round means no production at all.
• Connect it after the pre-filters. The pump must sit behind the sediment and carbon stages; unfiltered water abrades the pump.
• Isolate the vibration. The pump vibrates while it runs; fixing it directly to a hard surface increases the noise.
• Keep the electrical connection dry. The adapter and the cable must be positioned at a point away from any possible water leak.
• Do not bypass the pressure switches. The low- and high-pressure switches are the protection system of the pump; they must not be disabled.
• Bleed the air at first start-up. A pump started before the air in the line has been bled runs noisily and is strained.

Extending Pump Life

Booster pumps run for a long time without trouble under the right conditions. Most of the factors that shorten their life have to do with the rest of the system.

The most decisive factor is the condition of the pre-filters. A blocked filter strains the suction of the pump; the pump runs at a higher load, heats up and motor life is shortened. The second factor is the health of the pressure switches; a faulty switch keeps the pump needlessly on all the time. The third is dry running, and it usually leaves permanent damage in a single event.

Beyond these, fluctuations in the electrical supply, the use of an unsuitable adapter and a mounting with excessive vibration also shorten life. A simple check once a year — the state of the filters, the operation of the switches, the leak-tightness of the connections — prevents most early failures.

How to Assess Your Mains Pressure

The first step in deciding whether a pump is needed is knowing the existing pressure. Pressure varies with the time of day, the floor you are on and the length of the line; a single measurement may therefore not be enough.

There are practical signs that pressure is low. Flow weakening noticeably during a shower on upper floors, the water thinning out at the busy morning and evening hours, and the pressure tank never quite filling during the day are the first of them. If these signs are present, the reverse osmosis unit is being fed at that same inadequate pressure.

A second clue is the wastewater behaviour of the unit. When pressure is insufficient the system produces more wastewater and clean water production falls disproportionately. This picture is usually voiced as the complaint that "the unit wastes a lot of water"; the root cause, though, is pressure.

If pressure is adequate and production is still slow, the pre-filters and then the membrane come next. Following this order prevents money being spent on the wrong part.

Pump, Membrane and Tank: The Trio

In a reverse osmosis system these three parts work as a linked set. Changing one without taking the others into account does not give the expected result.

This table explains most of the "I changed one part but it did not get better" cases. The system is a whole; when a capacity increase is planned, the three parts must be reviewed together.

Pumps in Commercial and Industrial Applications

In domestic systems the pump runs intermittently: it cuts in as the tank empties and stops once it is full. On commercial and industrial lines the pump runs without interruption for far longer. That difference changes the selection criteria too.

Pumps suited to continuous duty are designed differently in terms of cooling and durability. RO Pump, 600 L/h is an example of this class. When a choice is made at this scale, the hourly flow rate of the line, the number of membranes and their array layout, and how many hours a day the system will run are all taken into account.

There is a second matter on industrial lines: redundancy. In a system tied to a production line, a pump failure means an immediate stoppage. That is why keeping a spare pump, or building a parallel pump arrangement, is a common approach on critical lines. You can find the details of setups at this scale in our Industrial Water Treatment and Industrial Packaged Systems categories.

The third matter is energy consumption. The annual energy cost of a continuously running pump can exceed its purchase price. Industrial choices therefore consider pump combinations that can work with low-pressure membranes; low-pressure RO membranes can deliver the same production with less energy.

Commissioning and First Start-Up

When a new pump is commissioned, the order that is followed matters both for the life of the pump and for the system working correctly.

• 1 — Flush the line. On a newly installed system, or one whose filters have been changed, the manufacturing residues in the line are flushed away before the pump cuts in.
• 2 — Bleed the air. Air left in the line makes the pump run noisily and strains it.
• 3 — Verify the flow direction. The arrow on the body shows the direction the water passes.
• 4 — Connect the pressure switches. The low- and high-pressure switches are the protection system of the pump; both must be in circuit.
• 5 — Switch the power on last. Running the pump before the water line is ready creates a dry-running risk.
• 6 — Watch the first cycle. While the tank fills, the sound, the heating and the vibration of the pump must be observed; once the tank is full, it must be verified that the pump stops.

Energy and Noise in Pump Selection

In domestic installations the pump is mostly mounted under the sink, that is, at a point close to the living space. Noise level is therefore a real criterion.

Noise comes from three sources: the running sound of the pump itself, the sound made by air in the line and the vibration coming from the mounting. The first depends on the model; the other two can largely be removed with correct installation. Using a vibration pad instead of fixing the pump directly to a hard surface reduces the perceived noise noticeably.

On the energy side, domestic pumps draw little and, because they run intermittently, their annual cost is limited. On commercial and industrial lines the energy item comes to the fore, because the pump runs without interruption for long periods. At this scale, combinations that can work with low-pressure membranes are considered; when the same production can be achieved at lower pressure, energy consumption drops as well.

A third criterion is durability. The cooling and the material strength of a continuously running pump are designed differently from an intermittently running domestic pump. Using a domestic pump on a commercial line ends in early failure, even if it works in the short term.

Do You Need a Pump: Decision Steps

Taking the pump decision in order prevents both an unnecessary purchase and an incomplete solution.

• 1 — Pin down the symptom. Is the problem the production rate, the water quality or the wastewater ratio? The three point in different directions.
• 2 — Rule out the pre-filters. A blocked sediment or carbon cartridge produces most of the same symptoms on its own. These are assessed first.
• 3 — Check the tank pressure. In systems with a tank, the most frequent cause of weak flow is the pre-charge pressure of the tank, not the production side.
• 4 — Assess the feed pressure. A drop on an upper floor, on a long run and at peak hours is the strongest indicator that a pump is needed.
• 5 — Assess the membrane last. If the output TDS value is not rising, the membrane is most likely sound.

When this order is followed, in most cases the source of the problem emerges in the first three steps. If a pump really is needed, it is seen clearly at the fourth step.

The Pump and Wastewater Relationship

Reverse osmosis systems produce wastewater as a matter of principle; this water prevents salt building up on the membrane surface. The wastewater ratio is not fixed, though; it varies with the feed pressure.

When pressure is insufficient the membrane produces less clean water, while the concentrate flow continues. The result is more wastewater for every litre of clean water produced. The user perceives this as "the unit wastes a lot of water" and usually blames the membrane.

When pressure is brought up to the right level, the ratio moves towards the design value of the system. So a pump does not only increase the production rate, it improves the wastewater ratio as well. This is a direct cost item in particular on industrial water treatment lines, where water consumption is high.

Common Misconceptions About Pumps

"I have fitted a pump, the water will come out cleaner." A pump does not clean water; it lets the membrane work at the pressure it was designed for. As an indirect result the output quality improves, but it is the membrane that does the treating, not the pump.

"A more powerful pump is better." A pump larger than necessary creates unnecessary strain on the membrane, spends energy and tires the system components. The pump must be matched to the membrane capacity.

"The pump should run all the time." In a healthy system the pump stops once the tank is full. Running continuously is a fault symptom; the high-pressure switch or the tank pressure must be checked.

"If there is noise, there is a fault." Pumps produce a certain amount of sound while they run. Excessive noise usually comes from air in the line or a loose mounting and is solved by correcting the installation.

"The pump is fitted ahead of the filters." Quite the opposite: the pump must sit behind the sediment and carbon stages. Unfiltered water abrades the pump and shortens its life.

Short Maintenance Schedule

The schedule below keeps the system working at the expected performance for years. The intervals are for typical mains water; they shorten with well water and in high-sediment conditions.

The most important side of this schedule is that the decisions rest on measurement rather than guesswork. TDS and pressure checks prevent both early and late replacement; early replacement means unnecessary cost, late replacement means damage to the equipment. When you cannot be sure of the state of your system you can make use of our site survey and fault diagnosis service; the site survey is free of charge if the unit is purchased from us.

Checklist After a Pump Replacement

A short verification after the new pump has been commissioned heads off later problems.

• Is the flow direction correct? Make sure water passes in the direction of the arrow on the body; with the connection reversed the system produces nothing.
• Does it stop once the tank is full? It must be verified that the high-pressure switch works. If it does not stop, the switch or the tank pressure is checked.
• Is there excessive heating? In normal operation it is warm; if it is very hot, the cause is dry running or staying permanently on.
• Are the noise and the vibration acceptable? The air in the line must be bled and, if needed, a vibration pad must be used.
• Has the production time shortened? The filling time of the tank must shorten noticeably compared with before; if it has not, the filters and the membrane are assessed.
• Is there a leak at the connections? In the first hours the fittings and the hose connections must be checked by eye.

Pumps in Direct-Flow Systems

In systems with a tank the pump runs intermittently: it cuts in as the tank empties and stops once it is full. In direct-flow systems there is no tank; the water is delivered to the tap the moment it is produced. This difference changes the duty regime of the pump.

In direct-flow installations the pump cuts in every time the tap is opened and runs for as long as the flow lasts. It must therefore suit both a more frequent starting cycle and a high instantaneous flow rate. Membrane capacity is chosen accordingly; a direct-flow system built with a low-capacity membrane gives inadequate flow at the tap.

The advantage of this arrangement is that it removes the problem of water standing in a tank. The disadvantage is that it calls for a high-capacity RO membrane and a pump to match it. The choice is made according to the usage profile and the budget.

Pump Selection in Summary

To sum up briefly: a pump does not treat water, it lets the membrane work at the right pressure. The choice is made by matching it to the membrane capacity; a pump larger than necessary spends energy and tires the system, while a small pump cannot give the expected production. Dry running and a faulty pressure switch are the two biggest enemies of a pump. Replacing the pre-filters on time protects the pump directly and extends its life. With these four headings kept in mind, a pump serves for years without trouble.

Pump Prices 2026

The prices below are the current values on the product pages and include VAT.

What Is Different About Buying a Pump from Water Point

• A 2-year warranty applies; misuse is outside its scope.
• CE certified products — we work with products that fall within the scope of certification.
• ETBİS-registered e-commerce — we are registered in the Ministry of Trade system.
• Invoiced sales — a legal invoice is issued with every order.
• Membrane matching — we determine the pump together with you, according to your membrane capacity and your feed water.
• Free site survey available — we establish on site whether the problem is in the pump or in the filters. see the details
• Türkiye-wide service network for industrial work — for domestic units we serve İstanbul and the surrounding provinces (such as Kocaeli and Tekirdağ).

Address: Mehterçeşme Mah. 1919 Sk. No: 54/B Esenyurt / İstanbul.

Could not find the spare part you are looking for?

Send us the brand and the model of your unit and let us determine the right filter, membrane, valve or resin together. The site survey is free of charge if the unit is purchased from us; if only a site survey and measurement is requested, a site survey fee of 2,000 TL applies.