Understanding water pumping engineering basics
So, you've checked with your state and found out that pumping water is perfectly legal in your area. You have a great source of water on your property and you've figured out exactly what you want to use it for. Now you're ready to learn HOW to pump water from it.
One little caveat before we dive in—this stuff can get really technical, so be prepared to exercise the left side of your brain for the next several paragraphs. But regardless of if you're installing the system yourself or are hiring a contractor to do it for you, knowing how it all works is extremely beneficial as it will help you better maintain, modify, and troubleshoot it in the future. Plus, if you are hiring someone, the more you know about the process, the better for everyone.
And if you are DIY from the ground up, all the details are extremely important in a water pumping system. An incorrectly-sized pump will either not provide any water at all, or worse, can cause long-term, very expensive damage. So, you can't cut corners.
OK, onward.
Flow Rate and Pressure
The first basic concept to understand is the relationship between flow rate and pressure.
Flow rate can be described as the volume or “amount” of water that comes through a water pumping system. A high flow rate is associated with more water and a low flow rate is associated with less water. Flow rate is expressed in gallons per minute or GPM.
Pressure is associated with the amount of force within the water system. From a practical perspective, a high-pressure shower is much more desirable than a low-pressure shower.
Ultimately, a water system with high-pressure and a high-flow rate is generally more desirable. The problem that pump science has to overcome is that there is a lot of resistance that prevents most water systems from achieving the target pressure and flow rate. This resistance can come in the form of gravity, friction, and distance of which water has to travel.
The goal of the water pump is to overcome this resistance and provide the user with the desired amount of water pressure and flow. But finding just the right pump is crucial. Too weak of a pump will result in poor pressure and flow or none at all. Too strong of a pump can result in damage and a shortened pump life.
The objective for the homeowner is then to find the right type of pump by calculating the exact amount of pressure and flow the system requires.
This is why it's important to determine the purpose of the water use upfront. A sprinkler system will have different pressure and flow requirements than a kitchen faucet.
How to size a pump
In pump engineering, flow rate is expressed at GPM and pressure is expressed as TDH. These two measurements will be unique to your system and we'll work through how to calculate them as you'll need them when you choose a pump.
Flow rate: Gallons Per Minute (GPM)
Faucet / Alicja / Pixabay
Flow rate is the overall amount of water that will flow through the system and out of the fixtures—a faucet, showerhead, garden hose, etc. Flow rate is expressed in GPM or gallons per minute in the United States. In other places, it may be expressed as liters per minute. Regardless of which unit of measurement is used, the concept remains the same.
The average flow rate for a home’s internal water system is typically between 6-12 gallons per minute, depending on the number of faucets, showers, and appliances being used. A larger home with more bathrooms and water fixtures will require a higher flow rate than a smaller home with fewer fixtures.
A single fixture flows at a rate of 1-2 GPM. By counting the number of fixtures, you can get a rough estimate of the flow rate demand for your home or cabin.
Determining your exact flow rate demand can be a very precise process that goes beyond the scope of this article. There are formulas to help calculate the exact number which may be necessary for large home applications. But for the purposes of drawing water for a small cabin or cottage, a ballpark range should do.
Once you've determined what your flow rate is, keep this number for later.
Pressure: Total Dynamic Head (TDH)
Total Dynamic Head Diagram / watermission.org
Measuring TDH is a bit more complex as it involves several critical steps.
As the pump creates pressure within the system, it needs to overcome a certain amount of resistance in order to provide the desired amount of water pressure at the fixture outlet. And because resistance comes in the form of various factors such as air pressure, pipe length, and friction, measuring it requires the sum of all of these factors.
The total sum of this resistance is called TDH or Total Dynamic Head.
Because TDH is a collection of different units of measurement, the simplest way to measure TDH is by feet.
There are 3 components that make up the Total Dynamic Head. They are the vertical lift (often called static head), friction loss, and operating pressure.
Vertical lift / Static head
Vertical Lift Diagram / watermission.org
Vertical lift, or static head, refers to the amount of pressure the pump will have to overcome when pushing water upwards. Because water is heavy, it creates a strong downward pressure on the pump, similar to how divers experience pressure in their eardrums as they descend further toward the ocean floor.
Vertical lift measures the total vertical distance the water must travel from the outlet of the pump to the highest part of the water system. It is important to note that vertical pressure doesn’t account for any horizontal distance in the water system, nor does it account for moving water. It only measures vertical distance while the water is perfectly still which is why it's also referred to as "static" head. Water in motion causes changes in pressure which we’ll account for later.
In order to measure vertical pressure, simply measure the distance from the pump outlet to the highest point of the water system. This distance is measured in units of feet. Keep this number for later calculations.
Friction loss
Friction Loss Diagram / watermission.org
Water in motion causes changes in pressure. As water moves through pipes, pressure is lost as it comes into resistance with the pipe walls and corners. The width and material of the pipes as well as the total distance that water has to travel through are all major factors in calculating friction loss.
This “friction” causes water to lose pressure and must be accounted for as the pump will need to work harder to compensate for it.
In order to account for friction loss, you’ll need to reference a friction loss chart or calculator. But before that, you’ll need to know the flow rate and the total length and diameter of your exit pipe. Some friction loss calculations involve as much detail as counting all the corners and right angles in the pipe.
Some of these numbers might not be available—and you'll just have to work with what you have. But as with any aspect of pump engineering, the more precise the calculations, the more likely the pump system works to your benefit.
If you’re purchasing a pump to add to your home or cabin's existing plumbing system, check with the original building plans to find out the length and diameter of your pipes—rather than having to measure everything yourself.
But if you’re designing your water system from the ground up, say for a small cabin or an outdoor irrigation system, the selection of your pipe materials will be a major factor. Larger-diameter PVC pipes move water much better than smaller copper pipes and rubber hoses. Consider 2" PVC pipes for better flow.
Once you’ve gathered these numbers, reference the friction loss chart to get the total friction loss number in units of feet. Save this number for later.
Operating pressure
Finally, operating pressure simply refers to the desired amount of water pressure at the point of use. Generally, people like a significant amount of pressure especially when using showerheads and kitchen faucets. Other appliances such as sprinkler systems or pressure tanks will have a specific operating pressure that must be met.
The operating pressure is largely preferential in most cases, but on average, the final operating pressure among all the fixtures usually ranges between 30 psi to 80 psi for most homes. But, like vertical lift and friction loss, we’ll need this number expressed in units of feet.
To convert from psi to feet, use this calculator. Or simply multiply the psi by 2.31.
Now that you have the numbers that make up the TDH, simply add them together.
Add the vertical lift, friction loss, and operating pressure together, in units of feet.
This final number is your Total Dynamic Head. It accounts for all the potential resistance that a pump will encounter when attempting to push water through the system.
Final Step: The Pump Curve
If you've made it this far, you should be very proud of yourself. These basic pump engineering concepts aren't easy to grasp and people pay lots of money to learn them.
But again, whether you're hiring someone to install the pump for you or you're the DIY type, understanding how your pumping system works will reap long-term benefits overall.
So, moving on.
Now, you should have your TDH as expressed in feet and your flow rate as expressed in GPM.
You'll need these two numbers when selecting a pump.
Pump manufacturers will display a lot of information about the pump such as horsepower, voltage, max PSI, and even flow rate in GPM. One of the misconceptions that new pump buyers usually have is that a pump with a certain GPM or PSI rating will produce that exact GPM or PSI in practice.
This is simply not true. Pump manufacturers make a variety of pumps in order to meet the various requirements that homeowners and consumers may have. The GPM rating on a pump will only produce that much under specific conditions. But it may very well be under or over that number.
As a buyer, what you’ll need to pay attention to most is the manufacturer's pump curve chart. Referencing your TDH and GPM, you’ll be able to determine which pump will meet your exact needs.
Here's an example of what a pump curve looks like for an above-ground jet pump.
Each pump will have its own performance curve unique to its specifications.
Notice the TDH scale on the left side of the chart and the GPM scale on the bottom then find where your numbers lie on each scale.
Draw a horizontal line from your TDH number on the left and a vertical line from the GPM number on the bottom. If these two lines meet at any point on the performance curve then this pump will meet your requirements. Ideally, you'll want the point to meet somewhere in the middle of the curve for optimum efficiency.
If the two lines meet anywhere above or below the curve, this specific pump will not perform to your requirements. You'll need to check out another pump.
Pump curves can look confusing. Luckily, a sales associate should be able to assist you in reading the curves and selecting the right pump for your needs. They’ll be glad you already have the TDH and GPM handy.
FAQs
How do you pump water out of a lake? ›
Assuming you can have a pump, a basic jet pump may do the trick. One of our staff members has a pump which sits on her dock with a hose and filter tip extending into the lake. The other end of the pump is connected to a one-way valve and then a hose. She pushes it on and voilà, the garden is watered!
Can you pump water out of a creek? ›Understanding water pumping engineering basics
So, you've checked with your state and found out that pumping water is perfectly legal in your area. You have a great source of water on your property and you've figured out exactly what you want to use it for.
The best way to draw water from a stream is to build a U-shaped “channeled” water catchment. This is just a wooden trough that has a screen that the water can drain into. Underneath the screen is a pipe. A ¾ “ black poly pipe would work fine.
What pumps pump water out of a lake? ›Sprinkler pumps are used to pump water from lakes, ponds, etc. to lawn sprinklers for irrigation.
What is the best way to filter lake water? ›Boiling is the best way to kill disease-causing organisms, including viruses, bacteria, and parasites. The high temperature and time spent boiling are very important to effectively kill the organisms in the water. Boiling will also effectively treat water if it is still cloudy or murky.
Can I pump water from my stream? ›To allow your pump to draw water from a shallow stream, you will need to use different techniques. One such is to create a small well that deepens the bed of the stream, thus giving you more room. Another technique involves placing a cover just above the intake to prevent it from drawing in air and creating a vortex.
How do you calculate water flow in a creek? ›Multiply the average depth of the stream by the width of the stream to find the area in ft2. Divide the distance traveled by the average travel time to find the velocity of the stream in ft/sec.
What is the best way to get water from a well without electricity? ›Hand pump
Some styles of hand pump can be mounted on a well without disrupting your existing electric well pump, and be used as a backup to deal with power outages. Do your homework to find the right pump, as some pumps will only pull water up a few feet and others can pull water out of a 200-foot well.
The Archimedes screw is made up of a hollow cylinder and a spiral part (the spiral can be inside, but here you'll put it outside the cylinder). One end is placed in a low-lying fluid source and the other end is tilted up into a higher discharge area. To move water all you need to do is rotate the screw.
What is the best flow for water pump? ›A higher flow rate will equal a bigger tank and more powerful pump. Bear in mind, a good flow rate for most taps is around 15 LPM.
How can I increase water flow without a pump? ›
Your house has a main water valve, usually located near the meter; the valve controls the flow of water into your home's pipes. Find the valve and check to see if it's completely open. Opening a half-shut valve is one of the quickest ways for increasing home water pressure.
What size pump do I need for my stream? ›Waterfall Pump Flow Rates
For waterfalls and streams, your pump should pump at least 100 gallons per hour for every inch wide the waterfall is. For more noise and "white-water" from your falls, increase the flow rate to 200 gallons per hour per inch of waterfall width.
There are three basic types of pumps: positive-displacement, centrifugal and axial-flow pumps. In centrifugal pumps the direction of flow of the fluid changes by ninety degrees as it flows over an impeller, while in axial flow pumps the direction of flow is unchanged.
Do you need a pressure tank for a lake pump? ›Pumps will work without a pressure tank, as there are automatic pumps fitted with a constant pressure controller so these pumps start and start on demand.
What is the cheapest way to pump water from a well? ›The sleeve bucket is the simplest and cheapest way to get water from your well without electricity. Also known as torpedo or cylinder buckets, the modern-day “well bucket is simply a long, skinny bucket that can be lowered into the narrow confines of a well casing to bring water to the surface.”
How do you filter water in a creek? ›Boiling Water: This is the most effective method to kill all bacteria. Just maintain a rolling boil for 1 minute (depending on elevation), let cool and you're good to go.
Can you filter water from a river? ›It's possible to filter river water for the purpose of removing contaminants and effectively purifying the water. There are a wide range of systems that can be used for the purpose of filtering river water.
What Micron filter is best for lake water? ›Typically, no single treatment method is enough to turn lake water into clean, clear, pleasant-smelling agua; most cottagers need at least one physical filter to first get rid of turbidity (experts recommend a five-micron sediment filter).
How deep can a pump pull water? ›The shallow well jet pumps draw water from one line situated in wells no deeper than a maximum of 25 feet deep. Deep well jet pumps use two lines, one for pulling the water, and one for pushing the water into the delivery system. Deep well jet pumps can pump water from wells that range from 25 to 110 feet deep.
Will a ram pump work in a river? ›Generally, streams, rivers or springs can be used as a source to operate these pumps, but a sufficient flow/capacity is needed to operate them, as a large portion of the water serves as an energy source that then exits below the pump and returns to the water source.
Can I use a submersible pump in a river? ›
It is not recommended to use borehole submersible pumps in a river or dam, instead of a standard centrifugal pump and motor. However, submersible pumps can be used in certain instances, as borehole submersible pumps do not get water damage unlike standard electrical motors if flooded.
How far up can you siphon water? ›The maximum lift a siphon can provide is 20 feet for most applications at sea level. If required, siphons may be secured with stakes or ropes (larger pipe diameters require more robust restraints). In most slope scenarios, 22.5-degree elbows should be used, however, 45-degree elbows may be used as needed.
How do you calculate gallons per minute in a creek? ›Multiply the velocity in feet per second by the estimated stream cross-sectional area in square feet to determine the flow rate in cubic feet per second. Multiply this figure by 450 to obtain the flow rate in gallons per minute.
What is the formula for stream flow? ›stream flow = velocity x cross sectional area
To measure velocity a float (orange peel) will be used to determine how fast the water is flowing.
Discharge = V x D x W
If length is measured in feet and time in seconds, Discharge has units of feet3/sec or cubic feet per second (cfs). Depth times Width gives the cross-sectional area. The shape of the channel is important because of the reduction in velocity due to friction along the channel margins.
Shut the system down and remove any debris in or near the suction strainer. Suction hose line is not air tight or is not installed properly. Shut the system down and check that the suction hose is correctly installed. If it is, check to make sure that it is not damaged, bent, or crushed.
Why will a water pump not prime? ›Causes of Pump Losing Prime
If there's no water in the line, air gaps cause suction to stop. Your well pump begins cycling air instead of water. Well pumps can lose their prime for several reasons. If your well water level is too low, you may have pulled too much water from the system.
The Swartzentruber Amish do not have running water in their homes, at least as most would understand it. Water arrives through a single line and is either pumped by hand or delivered by gravity from an external cistern.
Can you pump water from a well without electricity? ›If you experience a power outage, your well pump will not work. You will continue to use water for a short time, as your system draws the remaining water from the well storage tank. However, once that water is used – you will not have access to fresh water until power is restored.
Does water flow faster at the top or bottom? ›The slowest moving water is next to the bottom and each successive layer of water toward the surface flows faster than the layer below it. The fastest moving water is found just below the surface. This is because the air next to the surface creates friction which slows the surface water slightly.
How did the Romans make water flow uphill? ›
When the pipes had to span a valley, they built a siphon underground: a vast dip in the land that caused the water to drop so quickly it had enough momentum to make it uphill.
How many gallons per minute is good water flow? ›5 gpm (two fixtures running simultaneously at 2.5 gpm) is a good estimate of peak demand, for the typical household. Water wells that reliably yield 5 gpm should be able to meet peak and daily needs for most residences. Wells yielding less than 5 gpm, however, are sometimes the only water source available.
What psi should I pump water? ›Normal psi for a home pipe system is between 30 and 80 psi. While you don't want the psi to be too low, it violates code to be above 80. Instead, you should aim for a psi that's between 60 and 70.
Do you know how much flow you will need to pump? ›Calculating the desired flow rate of your pump is quite easy. Let's say, you want to transport 300 litres of a fluid every 30 minutes, then your pump system has to transport 300/30 = 10 litres per minute or 0.167 litres per second. This is the desired flow rate, which is usually calculated before the installation.
What are the 3 ways a water pump can fail? ›- Contaminated Coolant. One of the most common causes of premature water pump failure is excessive amounts of contaminants in your coolant supply. ...
- Mixed Coolant Types. Premature water pump failure may also stem from another common problem: mixing different coolant types. ...
- Cavitation.
The pumping capacity of the centrifugal pump can be achieved by either increasing the length of the pumping system or trimming of the impeller diameter. The diameter of the impeller has an impact on the performance of the pump [12]. The impeller trimming adjusts the centrifugal pump head and flows to the actual needs.
How do I increase water flow to my pump? ›Opening the valve will increase flow to the suction tank and at the same time reduce flow down the discharge line. This also has the result of wasting energy. Changing the speed of a pump changes the pump performance curve.
How deep should a stream be? ›Be sure to check the stream's depth from the skimmer. The stream should be 8” – 12” deep, which will allow fish to swim up to the waterfalls.
What size pump do I need for a 2000 gallon pond? ›Pond Size.
For water gardens (ponds with plants and goldfish) you want to circulate at least half of your total volume every hour. This means for a 2000 gallon pond you should be pumping AT LEAST 1000 Gallons Per Hour (GPH).
You need to think about how deep your water source is and choose a pump that can suck uphill. If you have a 10m deep dam or well, you will need a pump with at least 10m suction height head pressure capability. You then need to match the flow to the amount of water you want move.
Can you pull water from a lake? ›
If you pull water from a lake for irrigation, you have some version of a pump. A lake water pump is a great way to get water from the lake to the equipment you're using for irrigation. However, the water pulled from the lake likely contains sediment.
How do you pump water from a lake for irrigation? ›A: An irrigation pump station draws the water out through pipes which run from the lake under the ground. It's pressurized and filtered if required, and then the lake water is dispersed through your sprinklers.
How do you clear up water in a lake? ›Aeration. As lakes typically have slow-moving or stagnant water, it is very easy for nutrients to collect on the bottom of the lake and begin to build. Adding a simple form of aeration such as a solar fountain can keep the water moving. This will also increase oxygen levels in the lake.
Can a river flow out of a lake? ›A river's source could be a lake with an outflowing stream, such as Lake Itasca in the U.S. state of Minnesota, the source of the Mississippi River. A spring bubbling out of the ground can also be the headwaters of a river.
Why doesn't water drain from a lake? ›For a lake to keep its water over time, it has to be replenished. There are both natural and man-made lakes. The main way that water gets into reservoirs and man-made lakes is from the rivers and streams that were dammed to create them.
How do you prime a water line from a lake? ›- Make sure the power is turned off. Never leave a pump plugged in while you're working on it. ...
- Gain access to the pump system. ...
- Check for damage. ...
- Test a hose. ...
- Open the relief valves. ...
- Attach the hose. ...
- Turn on the water and wait for it to enter the tank. ...
- Turn the power on.
A submersible pump pushes water to the surface by converting rotary energy into kinetic energy into pressure energy. This is done by the water being pulled into the pump: first in the intake, where the rotation of the impeller pushes the water through the diffuser. From there, it goes to the surface.
Can you use a submersible pump in a lake? ›The use of submersible pumps in lakes, rivers, and other water bodies is becoming increasingly common. A submersible or deep well pump provides greater capacity and pumping capability at greater distances and elevations than a common suction or jet pump.
How do you know if lake water is clear? ›A clear lake is easy to spot. There are no visible particles in the water; it is not muddied by sediment or algae blooms. You can usually see fish swimming around at the bottom.
How do you clear up river water? ›- Properly dispose of hazardous household items. ...
- Reduce or eliminate use of fertilizers and chemical herbicides and pesticides. ...
- Make an appointment to service your septic system. ...
- Landscape with native plants. ...
- Eliminate bare spots in your yard. ...
- Make a rain garden.
How do you get water from a river? ›
...
There are three methods of developing streams and rivers and obtaining clean river water:
- Intake through infiltration wells and galleries;
- Direct intakes connected to mechanical pumps; and.
- Direct intakes using gravity flow.
The Self-Starting Siphon Tube uses the properties of momentum, cohesion, and capillary action to initially “pull” water out of the beaker and initiate the siphoning process.