How to reduce the pressure of a submerged pump?

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How to choose a submerged pump for a well

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The right submersible pump for the right need

The criteria of choice differ depending on the characteristics of the need for pumping and/or lifting (depth, type of liquids, use of pumped water) . Indeed, each type of pump has its specific construction characteristics depending on whether one is looking for a pumping in a borehole, in a well or in the groundwater table, sewage lifting to a collector, emptying a cellar or pumping into a tank or water tank.

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The purpose of this article is to provide specific choice assistance to feed pumps immersed in a well to create a drinking water system or not for a domestic facility.

Choose a water pump immersed in a well or a surface pump?

In terms of designations, we generally distinguish drilling pumps whose purpose is to raise water that is not suitable for consumption but conforming to domestic use (toilet, watering, washing machine), well pumps that can supply the house with drinking water or not drinking.

Do you need to choose a submerged pump or a surface pump (or hydrophore group) to pump into a well ? The submersible (submersible) pump, by definition below the waterline, is silent (noise absorbed by water) and does not require a technical (weather protection) space outside the well. It thus avoids the costs associated with a technical room that must be sealed to avoid long-term damage to surface pumps.

With exception, beyond 8 meters deep, surface pumps are no longer suitable in terms of power. It is best to choose a compact submersible pump that will have no difficulty pushing back to large manometric heights for high flow and pressure performance. At this depth the submerged pump is protected from frost, unlike the surface that needs to be drain and heat insulated in winter.

The pump body (and therefore the electric motor) are immersed in water. The pump is therefore cooled naturally, avoiding any risk of overheating. This immediate proximity to the water allows the pump to be permanently in charge. The risks of pump defuse due to a leakage defect (defective valve,…) in the discharge network are therefore avoided. When the goal is to connect to the home network, the necessary infrastructure (bladder tank, etc.) is comparable in both cases.

Therefore, for the needs of lifting water from a well, we advise you to choose a submerged pump.

Important parameters for choosing a pump immersed in a


Follow our methodology below and you can easily determine the appropriate submersible pump for your situation:

  • Typology of water to be suck. What is the particle size of solid elements in water? Should the pump be returned to clear water (< 4-5 mm) or dirty water (< 10 mm) ? This feature is essential in order not to clog the pump body and damage it prematurely. Clear waters are mainly runoff and rainwater. Dirty water is sandy water in the case of wells.

Source Photos: JETLY PUMPS

  • What is the minimum flow rate required (Q in m³/h)? It corresponds empirically to the daily consumption divided by 3.
    • For a dwelling it takes 200 liters per person for domestic use. House for 5 people = 1000 liters/day. Either an instantaneous flow rate of 3 m³/h for the pump. Average household water supply depending on the fireplace: 2 to 4 m³/h
    • For automatic watering, count 8 liters per m2 per day. A 500 m² garden (lawn, garden) will require 4000 litres (4 m3), or a pump flow of approximately 1.5 m³/hour. Sprinkler systems: 1.5 m³/h per sprinkler.
  • What is the total manometric height ( HMT in meters of water column) of the facility?
    • Gauge height for a submerged pump = elevation gain (1) load losses (2) working pressure (3)
    • (1) the max discharge height (in meters) = elevation difference = distance between pump at the bottom of the well and the highest discharge point
    • (2) singular load losses (in meters) due to friction in pipelines (elbows, junctions, etc.):
      • we need to know the flow rate, diameter and total length of the discharge line. Then the loss is determined by the attached abacus.
        • Example: Flow rate 2 m³/h, pipe diameter 1″ (26×34), piping length 100 m. Load Loss (m) = 9 cm/m x 100 m = 9 m
    • (3) the highest working pressure at the exit of the draw point:
      • Outside tap — usually 2.5 bar = 25 m, shower 3 bar = 30 m, 3 bar sprinkler per sprinkler = 30 m.
    • Example (domestic use): HMT = 7 meters (well depth) 3 meters (floor tap) 5 meters of load loss (pump 3m³/h) 25 meters (working pressure) = 40 m. The diagram below indicates that the Idramatic pump provides a flow rate of more than 3 m³ at a manometric height of 40 m. It is therefore adapted as needed.

    • the pressure decreases the higher the lift depth, the right pump power should be chosen according to the depth As of the well and the characteristics of the installation. Each pump is described by a power abacus (power, pressure, flow) to be referred to to ensure it meets the need.
  • What is the diameter of the drainage and distribution pipes ? The diameter should be chosen in correlation with the pump flow rate. If the nominal flow rate is too high for pipelines, it must be increased or the pump power is reduced accordingly. See the abacus.
  • Complementary equipment? Will the pump be combined with a pressure booster unit to provide sufficient pressure for use (domestic, garden watering, etc.). Some Submersible pumps provide sufficient pressure autonomously, making the overpressure group unnecessary.

Choosing the best submersible pumps for shallow well: our selection

of submersible pumps: performance, quality, durability, innovative features

Sizing Max. immersion depth Max Flow/Pressure Significant competitive advantages
GUINARD pump model IDRAMATIC 1200 800 M² garden 4 persons 12 meters, clear waters 1200W, 1CV, — 5.5 m³/h for HMT max = 65 meters Performance, multi-cellular (AISI 304 stainless steel pump body and turbine), self-priming, lack of water safety function, integrated return valve, automatic anti-lock safety every 100 hours, overpressure without bladder tank, ready to operate (plug & pump), 3 year warranty.
DRILLING PUMP 3″ GRUNDFOS SQ 2-70/30M 200 M² Garden 4 persons 17 meters, clear waters HMT max: 88 metres, Max flow rate: 3.4 m³/h Built-in dry running protection, soft start, integrated check valve, undervoltage and surge protection, heat protection, high hydraulic and motor yields, excellent wear resistance

Submersible pumps require annual maintenance.

Additional information

  • The Well water is not often drinable because filtering sedimentary rocks is not enough to stop pollution (contaminated rainwater, pesticides, bacteria, nitrates, etc.).
  • The pump should not be laid on the bottom of the well (so as not to suck sand and dirt), nor placed too close to the walls of the well. To avoid this, it is necessary to suspend the pump with a thread (usually supplied).
  • The presence and use of a domestic well (even for watering) must be declared in town hall. Connecting to the household network (WC, washing machine, etc.) involves an application for a permit and the establishment of a parallel and separate drainage system from the wastewater and stormwater network (so as not to contaminate the urban drinking water system with polluted water). Since 2009, the legislation requires owners to install a meter raising the pumped volumes and to pay a fee.


IDRAMATIC 1200W GUINARD up to 12 m depth



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