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Determining HP of Pump for Lifting Water

Kindly let me know the following;

How to calculate the HP of the water pump motor for lifting water from sump to Roof tank in residential buildings? Is there a general rule to be followed? Any standards or recommendations may kindly be provided.

B M Singh



1. How to calculate the HP of the water pump

Dear Sh BM Singh. 

Bookish answer to your question is available on 100's websites on this internet. You might have searched various sites to quench your thirst to satisfy you fully. You might have found that there are only two variables required to calcuate the water pump HP. 1) height of total lift of water 2) required flow Please take total height in meters and flow required in liter per minute. now multiply height(in meters) and flow (in liters per minute) now divide this by 4500 you will get theoretical HP of the pump.

Now there is a secret to calculate actual HP of the pump In my practical experience i did not find pump efficiency more than 30 %. In most cases it is less than 30 %. So to calculate actual HP you should multiply theoretical HP by 4. Actual HP is 4 times more than theoretical HP.

Second secret, Please calculate total suction lift from pump to sump bottom. please ensure water pump is capable of producing so much suction.

Third secret, please add 20 % to your actual height of water lift. These are called frictional losses.

Fourth secret, submersible pumps are more efficient than monoblock pump.

I think above points are useful to satisfy your question


AK Singla

Power Utilities Engineer, Panipat Refinery Panipat



2. Water lift for glacial spring - East Montpelier, Vermont

Mr. AK Singla

I am the project manager for Antonovich Springs. I am renovating a glacial spring in East Montpelier, Vermont. Our spring supplied the state capital in Montpelier.

Can we talk about original gravimetric pipe design (4 miles) from 1820, and proposed new pipeline from spring (350 gal/min)  1100 ft to the top of a hill and farm at 1200 ft than down to our factory on the river or back through farm to city park & forest. Its quite beautiful and I want to keep it simple.

Thank you for your risk analysis.
Dean Loren
718 277 1367

3. Determining HP of Pump for Lifting Water

The following link provides you a simple calculator to workout the HP of a pump.

This inolves understanding of the pumping head, size of pipe, water requirement, friction losses, etc.,

The better way to calculate the HP is to consult a pump vendor and use the pump rating chart of a pump your planning to use.

4. Thank you for the site you've given

Thank you for the site you've given. The better thing is that it is in excel form which can be used also as reference.

5. Dear B. M. Singh, One first

Dear B. M. Singh,

One first needs to determine the total head of water required i.e the length of the piping from the foot valve inside the sump to the pump suction flange and then add the height of the piping from the pump discharge flange to O/H tank. This is the total discharge head required. The horse power or Kw required is calculated as follows:

Kw =flow in m3./hr X total head in metresX density of water / 3.6X102,000 X pump efficiency (in decimals).

It would be simpler for you to contact the sellers of pumps to come take a look at the layout of his sump, O/H tank, etc. take measurements and then quote for a suitable pump. The seller has to know how to determine the power required from the drive motor.

Ion Exchange

6. What kind of submersible pump should be used?

Please advise the submersible pump capacity for lifting water from a borewell having a depth of 450 feet and water in the borewell yield is 2 inch. I require the water to be lifted to a height of 25 meters to the 8th floor building which is near Sri Mookambika temple Kollur. The water is required to fill 15,000 lts of tank in less than one hour. if you have Danfoss pumps please suggest the model and send a quotation accordingly. A lso I am looking for a water filter to be connected to the delivery line at the roof top of the building. I want to eliminate the small sand particles that come at the time of starting of the pump (old pump ) and remove slight discoloration of water that occurs during the rainy season. Note test was done by Surathkal Institute and certified that was is good for drinking purpose.

Thank you and best regards,
Pradeep Kumar

7. Dear B. M. Singh, For

Dear B. M. Singh,


For calculating the horse power of the pump for lifting the water to roof top, it will be required to do the following:


  • The important parameters are the amount of water to be lifted (discharge) and the head from location of the pump to the roof top and the time in which, we want to lift the requisite quantity of water.
  • Calculate the discharge of water to be lifted. For example ,if the per capita consumption is 200 lpcd, the days consumption will work out to  1000 liters or 1m3 and if it were to be lifted in 15 minutes, the requisite discharge will work out to (1m3/ (15*60)sec. or (1/900) m3/sec
  • The formula for calculating the HP of the pump is (Q*1000*h)/ (75*eff) where is Q is the discharge in cum/sec; 1000 is the specific wt of water and h is the lift calculated from the location of the pump to the roof top. For a 3 storey building it would be 10 to 11 m. eff is the efficiency of the pump.
  • By applying the above the requisite HP for the example above would work out to 0.25 HP, with a pump efficiency of 70%. However the next issue would be to see what capacity pumps are available in the market, which may be usually more than 0.25 HP. The same should be procured.


With regards,


Vijay Kumar


Head-Water Resources/Senior Consultant-Water Resources

DHI-Water and Environment

New Delhi-110019

8. How to calculate the HP of the water pump

Dear Sir,

The horse-power (H.P.) of a pump can be determined by calculating the work done by a pump in raising the water upto H height in meters

Let the pump raise ‘W’ kg of water to height ‘H’ m

Then work done by pump = W X H Kg m  = WQH mkg/sec

Where W → density of water in kg/m3. Is equal to app. 1.0

Q → water discharge by pump in m3/sec

The water horse power, Pw =  (W × Q × H) /75   and the break horse power  =  ((W × Q × H) /75 X Efficiency }

Power or energy required per second to the pump water is Pw = QH kw  and this determines the horsepower

Horse power of the pump is Pw x 1.341 HP

The above is the general formula.  But for the design of your system, you should know the following in addition, the lift and the total head.  The total head involve, friction loss while the water flow through the pipe, bed loss, loss at valve, junction, at various changes of diameter of pipe etc.  Hence to design a system if you know the all values, then you can design the pump and motor horse power, (Discharge rate, Lift, total head)

The total head involve various frictional loss computations at different stage.  These are useful to understand the system and design as a whole.

But in practical cases, due to exhaustive trial and error statistics, either recorded or practically performed  and assessed, given the discharge, pipe diameter, and total height from sump to tank, an experience mechanic can tell the required horse power of the pump/ motor and pipe diameter. 

PVC pipes and HDP hoses have low frictional loss than the metal pipes. Depending up on your overhead tank size, available volume of water, you can chose the pipe diameter and horse power by varying the time of pumping. If you want lesser time, choose higher horse power which is within the available discharge

For a 5 member family, 500 liter capacity tank,  filling twice a day will suffice the need.  Assuming the tank is at a height of say about 25 feet you may fit 1.5 h.p centrifugal self priming pump to lift water from 5 feet depth sump for a pipe diameter of  one quarter inches.   This might fill your tank of 500 liters in maximum of about 10 to 12 minutes.  However this depends on the quality and make of the impeller and motor. An ISI standard pump might do.

This is for your enlightenment.




9. Suitable pump/motor for 10 feet depth sump 20 feet lifting

Dear Mr Raja Mohammed

Please suggest the best pump with product make for my sump. Specifications are as follows:

Height: 7 feet; Length: 6.5 feet; Width: 6.5 Feet


Mohideen, Group Five - Saudi Arabia


10. What is the data based on which we can install a lifting pump?


On which basis can we install a lifting pump if we are going to have a facility for drinking water with the aid of pump for 500 users? What will be the procedure to prepare for project?

11. Determining HP of Pump for lifting water up to 30 feet

I have to lift water to a height of 30 feet to fill a tank of 2000 liters through a pipe of 0.5 inch from the depth of 2 meters.

Kindly suggest what horse power monoblock pump is needed to meet this requirement?

Siddharth Kumar

12. Pump for lifting water from sum to rooftop

Respected Sir,

Namaskar & greetings.
We have a sump below the ground level, its depth is of 3 feet appx wherein we fill drinking water and with help of three phase 1 h.p. pump we lift water appx 50feet (16 metres) to house roof and store in rcc water tank of 12000 litres for use of 9 families. This pump has become very slow and is also very old. We think the earlier owner put it about 25 years ago. Can we have this pump modified or renovated for use or should we put a new one?
Please also suggest latest pump and with what h.p. as we wish to fill the overhead roof tank of 12000 litres in 1 hour only due to electric load shedding. An early response will be highly appreciable.
Vinoo Khanna
Plumbing contractor, New Delhi

13. Water pump for single family residential bunglow

Members and Experts,

I am not an engineer. But need to replace my water pump. I currently have a underground tank, which gets filled twice in a one day and an overhead tank attached to it. There is a submersible pump in the tank below, and a pump near my overhead tank. This pump above is a nuisance. Its switches on and off (cranks), each time any tap is opened. When it cranks, it creates huge fluctuations in my overall voltage. It can be seen in AC, light bulbs, fans. I am scared that this is effecting all my electronics/pump aswell in a bad way.

Is it the pump which is causing the problem because it is located next to overhead tank?

Or is it the Kirloskar brand pump, which is causing the problem?

14. Question regarding pump choice for well

My well is 300 ft from my office. I need to supply water to the tank which is near the office. My question is, what type of water pump should I go for?
I wish to know the following:
01. Electric source
02. 1" supply pump
03. Pump must be fitted in the well
04. Supply speed and pressure of pump are not important
05. Need:- water must be pumped
More information
01. Tank is 300 ft from the well
02. Water is at a depth of 15-20 ft in the well
03. Total height - 35ft (20ft from foot valve to pump (Max). and 15ft from water pump to tank)
04. Tank 1000 liter capacity
05. Water needs - 1000 liters per day (maximum)

Please denote the suitable pump and the features of the pump.

Thank you

15. Pl suggest capacity of motor & pump for 2 storeyed apartments

Please suggest a suitable motor and pump to be used for 2 storey building. Water suction is from 25 feet underground and to deliver to the water tank at roof at a height of 25feet. Also please provide the water tank dimensions. In the two storey building, a total 5 families will be accommodated (25 persons)

16. What hp pump is needed to lift water to a height of 40 ft?

I have to lift water to a height of 40 feet to fill a tank through a pipe of 0.5 inch from the depth of 10 feet. Kindly suggest what horse power pump is needed to meet this requirement?

17. What hp pump is needed to lift water to 40ft,2500-3000 PSI?

What would be the specification (horse power) of the pump required to pump water to 40 feet height with 200 bar pressure / 2500-3000 PSI.? Any particular company pump of your suggestion?

Thanks in advance,


18. What is the number of power units consumed?

What is the number of power units consumed by one hp motor to lift 1000 liters of water from sump at ground to a tank of 30 feet high.

19. Need information on the type of pump to buy


I need to replace my old relic of a water pump.  The details are as follows:

  • Length of piping (3/4" dia) from foot valve to pump inlet 45'
  • Length of piping (1/2" dia) from pump outlet to roof tank 15'

It's still working despite its leaky water seal and eroded shafting. I believe a 1/2 HP one would suffice for my needs.

Could you please recommend a reliable brand and type of pump I should go for in the present market? Hopefully one that has a track record of reliability equal to my old water pump.

20. How to calculate water volume that is pumped to the storage tank

There are two motor pumps of 5 hp and 3 hp and the pump outlet has a 2 inch dia water pipe in our residential building.

I would like to know how to calculate the water volume in the upper tank, if we run the 3 hp motor for 30 minutes?

What would be the time required if same amount of water has to be lifted by 5 hp pump?


21. Need info on pump capacity to pump water from lake

We have got a small farm where the borewell has dried up. Around 300ft from my farm, there is a lake belonging to the government, we have got permission to pump water for agriculture.

Now my problem is:

I have to keep my pump at my farm and draw a pipe to lake. Will the pump suck water from lake which is 300ft and then pump it. the reason I have to keep pump in farm is that I do not own land near lake. Kindly suggest the pump capacity to be installed for this.

Kind regards,
S R Harekal

22. Need help with capacity of motor to lift water from sump to OHT


Please suggest a suitable pump set with motor for lifting potable water from sump to over head tank, total head 110 mtrs, rate of discharge 1320 LPM.

23. Need pump details for drying a pond


I need to dry my pond of size 1 acre with water level 12 ft. Suggest diesel requirement & details of electrical pumpset to be used for this purpose

24. How much power is needed to pump water up to 200 ft ?


I am using a submersible water pump to pump water from a well 100ft deep to a tank located at a height of 10m from ground level. How much power or energy will I need to use? What is the best flow rate to pump water into the tank?

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