All posts by jstryker

Can I Pump my Irrigation Water from a River, Creek, or Pond?

Q.  We live on a river.  I would love to plant some interesting things on the bank below our home but with the price of water these days I would love to be able to pump some river water up to do the job. Do you think that that is something we could do without spending a fortune?  It would be great to have a soaker system.

A.   First, you must have the right to take water from the creek, river,. pond, etc..   This almost always means you need to talk with the US Fish & Game Department, State regulators, and possibly the Environmental Protection Agency (or equivalent agencies for whatever country you are located in.)  If you take water from a creek or pond or any other natural body of water in the USA without checking on the legal rights and requirements you can get into a lot of hot water, fast.  The fines penalties and restitution costs can be enormous.  So before you do anything, start doing some calling around.  Be safe, not sorry.  If you don’t know who to call, try calling the local County or Parrish Planning Department, they should be familiar with the agencies that regulate water and be able to point you to the right people.

Yes, from a physical standpoint it is not difficult to pump the water.  The cost depends on how fancy you make it.  My parents had a cabin on a river in Oregon.  They simply had a small portable pump that sat on a concrete block and was chained to a tree.  One end of a 15′ garden hose was attached to the pump intake, the other end of the hose had a piece of window screen tied around it to create a home-made filter and keep out small fish and junk.  The end of the hose with the screen filter was tied to a concrete block and dropped into the river.  The pump outlet was attached to a second garden hose, this one was 150 feet long.  A long extension cord went from the pump to the power outlet at the cabin.  They put a sprinkler on the end of the hose, placed the sprinkler where they wanted water, then plugged in the pump.  Simple, cheap.  You could easily semi-automate that by simply plugging the pump’s power cord into a timer to turn it on and off.

A fancier system is certainly possible.  The pump still needs to be portable in most cases.  The pump has to be mounted less than 8 feet above the water level (the closer the better.)  You need a pad of some sort to put the pump on, but it is best if the pump can be easily moved, especially if the water level fluctuates in the creek or floods.   There is also the possibility of using a submersible pump.   A submersible should not sit on the bottom of the stream if there is a lot of mud and silt in the water that would get sucked into the pump.  If you have a floating dock or a pier an alternative is to place the pump on it (or hang it below the dock in the case of a submersible pump.)  Submersible pumps are often strapped to the side of pier pilings.  Be sure to read installation instructions for the pump, many pumps have very specific positioning requirements, some submersibles must be installed inside a special sleeve.

You can get about as fancy as you want- using automatic controls to start and stop the pump and also to open and close multiple irrigation valves.  Many irrigation controllers have built in circuitry that will start and stop the pump for you using a electrical relay.  If you do it yourself, and you need only something similar to my parent’s  small pump  you could probably install a pump  for around $200.00.  The price can go up fast as you get bigger and fancier, $1000.00 is not an out of line figure for a pump system capable of watering an acre or so of yard.  The wiring for the pump automated controls is a bit tricky, so most people would want to have that part done by a electrician.  How much that costs depends on the length of wire needed to reach the pump.  One option to look at when you get to larger irrigation systems is a pre-constructed pump unit.  This consists of the pump and all of the needed controls for it pre-installed and pre-tested on a metal frame.  You just hook up the pipes and wires to it and turn it on.

You may also need a storage tank for the water, especially if you have a small water supply (like a creek.)   That way you could pump a small flow continuously from the creek  to fill the tank.  Once in the tank the irrigation water would either be pumped out of the tank to the irrigation system by a second pump, or if the tank can be located 30′ or so higher than the level of the irrigated area, you could use gravity flow from the tank.  (If you want to use sprinklers the tank would need to be at least 60 feet higher to create enough pressure for a small sprinkler.)  The tank will probably need to be a lot larger than you think.  Typically they are 5,000 gallons or larger.  To find out what size tank you will need you need to determine how much water it will take to irrigate your area.  See How to Estimate Irrigation Water Quantity Needed for instructions on estimating your water requirements.

One last word of warning before you start:  PLAN FIRST, BUY LATER!   Don’t run out and buy an “irrigation pump” first!  Most pumps sold with the description “irrigation pump” are designed to operate a single sprinkler on the end of a hose.  You need to design the irrigation first, then you will now how much water volume AND water pressure the pump will need to produce.  The Sprinkler System Design Tutorial takes you through the process of irrigation system design and finding the right pump size.  It’s at  https://www.irrigationtutorials.com/sprinkler00.htm

Why not use those huge sprinklers?

Q.   I don’t understand why I can’t apply the same guidelines from your tutorial and choose 2 or 3 heads with 70 foot spacing?  That would mean a lot less sprinkler heads on my large acreage lawn.  Other than not being able to aim them as selectively, I’m missing the reasons I shouldn’t go this route.  But you caution against it, so I’m sure I’m missing something.

A.  Someplace around 55 foot spacing things start to get all screwy.  They do make sprinklers that will shoot that large radius.  They are pricey, the cost works out about the same per square foot irrigated regardless of the spacing (funny how that happens!)   The problem is there’s just too much wind drift, evaporation, etc. at those wide spacings.  Plus to get water to fly those long distances you need big, heavy water drops with lots of momentum.  Those big drops just beat the crud out of the lawn, and cause compaction of the soil.  Think of what it would be like if a really hard rain storm occurred each time you watered.  Where the huge droplets don’t compact the soil they may erode it.  Golf courses and parks have fought this problem for years.  Most city parks have now settled for 55′ spacing rather than deal with the grief of citizen complaints about dead grass.

The bigger radius heads work better with pasture grasses, where long unmowed grass blades soften the droplet impact and a few dry spots and general “ugliness” aren’t as important.

It also takes lots of water pressure and volume to get that water out there.  70 feet radius means you need 70 PSI and 30 GPM at each sprinkler head.  That means probably 85 PSI or more coming out of the pump.  Most systems with big sprinklers like that run at over 100 PSI of pressure, which means lots more wear and tear on the system, and a shorter life-span.   With those high pressures, design becomes critical, mis-design a single thing and it is unforgiving; water hammer can rip the whole system apart in a big hurry.

Then there is the safety issue.  You ever been hit by a 30 GPM stream of water flying from a nozzle at 70 PSI?   I have, it knocks you on your butt and hurts like hell!  Keep in mind that the really big impact guns used on farms reverse with enough force to kill you if you are struck in the head by the sprinkler arm.   Liability is the biggest reason that parks and golf courses are ditching the big water guns for smaller sprinklers.

Bottom line is that using big radius sprinklers just gets really tricky and the results are ho-hum at best.  It’s not a good solution in the vast majority of situations.  If you do want to mess with it, get professional help with the design.  Most of the sprinklers over 70′ radius are only sold by agricultural irrigation dealers.

Large Radius Sprinklers
Big Irrigation Guns in Florida

Winterization for Areas with Periodic Freezing

Q.  We typically have hot summers (month long +100 degree weather,) but recently we are also experiencing very cold winters (recently had 0 degree with -17 degree wind chills that froze a lot of pipes in the city.)  Do you have any suggestions that would be useful about winterization for  Southwest USA irrigation, or any particular materials that are specific to this area I should ask for?

A.  This is a situation which occurs all through the southern US, as far inland as Nevada (Reno sees this type of temperature extremes every year), and up the west coast all the way into the Pacific Northwest.   In these areas you see overnight freezing, which is typically followed by above freezing daytime temps.  To make it worse, it is often necessary in these areas to irrigate during the winter months due to drying wind and high daytime temperatures!  In these places we generally don’t winterize irrigation systems by draining the pipes in the winter, as the soil insulates them enough to prevent freezing.  Sometimes we bury pipes much deeper in these places, say 18″, to keep them below the frost level.   Any above ground equipment will need insulation installed on it to prevent freezing during the nights.  So generally I wrap the above ground pipes with foam or fiberglass insulation, extending down underground to below the typical freezing depth.  Where exposed to sunlight I wrap the insulation with a high grade pipe wrap tape that is UV resistant, or with metallic tape.  Without protection foam insulation degrades pretty fast from sunlight exposure.  Do not use standard duct tape, it is not UV resistant and will be a mess within a year or two.  For above ground valves and backflow preventers you can purchase insulating covers that can be placed over them like a big bag, (one brand name that comes to mind is Polar Parka) or you can wrap them in fiberglass pipe insulation wrap.  Just make sure water can drain out of the bottom someplace, in case there is a leak.  Fiberglass insulation must be wrapped with plastic tape or something else waterproof to keep it dry, it will not insulate if it becomes wet. You can also put thermostat controlled electric pipe heaters on the pipes as another option.

The killer problem is when you have hard freezes that last for several days.  Insulation doesn’t work very well during long duration freezes, as the cold has time to penetrate the insulation.   In areas where freezing weather lasts longer than over-night, but you still need to keep the irrigation system operational, it is a good idea to install electric pipe heaters on backflow preventers and above-ground valves.  If you don’t need to irrigate during the winter in hard freeze areas, then you should do a full winterization process that includes draining water from the pipes.  For more details on winterization see the Irrigation System Winterization Tutorial.

Outlet Pipe Size for Pump- is a Bigger Pipe Better?

Q.  I’m designing a pump system from a lake and have read and understand your calculation of FT HD needed for pump selection but it seems that the upstream (uphill) pipe diameter would be a factor in the calculation.  I was going to use larger pipe to reduce pipe resistance and valve pressure drop but it seems to me the weight of the additional water (back pressure) would be higher for a  larger diameter pipe than a smaller one.  It must be easier to push water up a 3/4″ column than a 1 1/2 inch column.  You mention nothing about this.  Excluding pipe resistance, does the pipe diameter play a roll in taxing the FT HD required?  Rephrased –  Does a larger diameter column of water have any effect on the static pressure or force required to move it?

A.  The short answer is that the larger pipe would be better because there would be less pressure loss in the pipe.  This is due to less “friction loss” as the water flows through the larger size pipe.  The larger amount of water in the bigger pipe has no impact on the water pressure.   A smaller pipe may create more friction loss however, so it can be worse than a larger pipe.    To find out, you need to calculate the friction loss in the different sizes of outlet pipe based on the flow and pipe size.  See the Friction Loss Calculators to calculate the friction loss in pipes.

More detailed answer:
One of the really hard to grasp principles of hydraulics is the relation of volume of flow, pressure, and the weight of water.  Odd as it seems a larger pipe will actually be easier for the pump.  It’s not the volume of water, but the height it is lifted that matters.  In a way this is a variation on the old saying “which weighs more, a pound of feathers, or a pound of lead?”  Obviously both weigh a pound!  This version could be phrased “which is easier for the pump, 5 GPM in a 1/2″ pipe or 5 GPM in a 2” pipe?  Neither because 5 GPM is still 5 GPM regardless of the pipe size!  Yes, you would need more power if you were actually lifting more water, also we would need more power to lift the water higher, but neither is not what is happening.  The amount of water nor the height we are lifting hasn’t changed.

The other issue here is flow through a pipe.  This is the issue that actually makes the smaller pipe potentially worse than the larger.  Because the smaller pipe is smaller it is harder to force the water through it.  The resistance of the walls of the smaller pipe causes pressure loss as water flows through.  this is commonly called “friction loss”.  How much friction loss occurs depends on the flow rate and pipe size.  Both higher flows and smaller pipes sizes result in greater friction loss.  This is the only reason a smaller pipe would be worse than the bigger pipe.  How much worse is dependent upon the actual flow rate and pipe size.

As a general rule (ie: not always true, but is most of the time)  the pipe size of the pump outlet is almost always smaller than the size of pipe that will provide optimal flow from the pump.  In other words, if a pump has a 1″ threaded outlet, it is very likely that a 1 1/2″ pipe would be attached to the 1″ outlet for use as the outlet pipe.  Pump manufacturer’s tend to use smaller size inlets and outlets to save money.

More technical answer:
Think about feet of head.  As discussed in the Pump Tutorial, the number of feet of water depth determines the water pressure.  So 80 feet of water depth equals a pressure of 80 ft. hd.  This pressure will be the same regardless of the pipe size.  The water pressure at the bottom of an 80′ high 1/2″  pipe is exactly the same as the water pressure at the bottom of an 80′ high 6″ pipe, even though the 6″ pipe holds a lot more water.  A pump actually works by creating water pressure.  So for the pump there is no difference between pumping into either size pipe, the water pressure required to move the water into the bottom of both pipes is the same.  Now the pressure lost as water moves through the two pipes will be different.  Assuming a high rate of flow, a lot more pressure will be lost due to friction in the smaller pipe.    So for that reason using a larger pipe will be better.  Depending on the flow, however, it may be only very marginally better.  To find out you need to calculate the friction loss in the outlet pipe based on the flow and pipe size.  See the Friction Loss Calculators to calculate the friction loss in pipes or tubes of various types.

Can I Just Punch Holes in a Tube to Make Drippers?

Q.  I’m installing a drip irrigation system and to save some money, I decided to buy inch wide black tubing.  I used a hot needle to make some small holes every 27 inches apart from each other, but when doing water pressure testing , some holes emit more water than others.  What do you recommend in this case? Is it a bad idea to punch my own holes?  Or is there a way to do this with an even result in each hole?

A.  Just punching holes doesn’t work well, as you discovered.  It’s almost impossible to get the holes uniform in size, and even if you did, variations in the water flow patterns inside the tube would make each hole emit water at a different rate.  The solution is simple.  You need to install barbed drip emitters in the holes.  The drip  emitters are small, plastic, highly-engineered devices that regulate how much water comes out, so that each hole gives a very uniform rate of flow.  A typical emitter (sometimes called a dripper) is about the size of 5 dimes stacked on top of each other.  The emitter has a barbed inlet on one side that pushes into the holes in the tube.  You just snap the barb into a hole punched in the tube.  Then the water drips evenly out of an outlet hole on the other side of the emitter.  You need one emitter for each hole.  Emitters are typically sold in packages of 10, 25, 50, or 100 emitters per package.

Since you already bought tube, cut off a small piece of your tubing that has a hole in it and take it with you to the store.  1″ black tube is probably not made for use with drip systems.  It probably has a thicker wall than standard drip system tubing, so the barbs on some brands of emitters may not be long enough to push all the way into the tube and lock in place.  Most brands should work, but in your case it would be best to test it at the store so you don’t have to make another trip back to the store if the emitters don’t fit.  The emitter’s barb should push all the way in and lock the emitter onto the tube.  It should not easily pull out.

It might be a good idea for you to read the Drip Guidelines at https://www.irrigationtutorials.com/drip-irrigation-design-guidelines-basics-of-measurements-parts-and-more/ .   There are a lot more mistakes you can make, and I’d hate to see you waste any more of your time and money.

How to Estimate Water Useage Required for an Irrigation System

The amount of water needed for irrigation depends on many different factors.  A reasonably accurate estimate of the amount of irrigation water needed can be made using Eto data for your actual zip code.  “Eto” is the amount of water needed for irrigation, based on scientific research.  You can find the historic Eto for any zip code in the USA at the website http://www.rainmaster.com/historicET.aspx courtesy of the Rainmaster irrigation controller company, who makes very good “Smart” irrigation controllers.   I use one of their Eagle model controllers on my own home.  (Rainmaster get a plug from me as well as a big “thank you” for providing the ETo look up service online.)  Unfortunately the Eto value only tells you how many inches per day are needed, which for most folks is a meaningless value. It makes more sense if you think about rainfall which is often also measured in inches.  If you find you need 0.20 inches of irrigation, then 0.20 inches of rainfall would provide the required water.  But most people in the USA want a value in gallons, which requires you to provide a little more information about your yard.  Then you plug the values into a simple formula, and do a little multiplication and division on any calculator.

Formula to calculate the gallons of irrigation water needed per day:
(Eto x PF x SF x 0.62 ) / IE  =  Gallons of Water per day

Values for the formula:
Eto: Get this from http://www.rainmaster.com/historicET.aspx .  Enter your zip code, or a nearby zipcode, and the website will give you the average daily ET value for each month of the year.  Use the highest value or the “suggested reference value”.  Usually they are the same thing.

PF: This is the plant factor.  Different plants need different amounts of water.  Use a value of 1.0 for lawn.  For water loving shrubs use .80, for average water use shrubs use 0.5, for low water use shrubs use 0.3.

SF: This is the area to be irrigated in square feet.  So for a 30 foot x 50 foot lawn you would use 1500.

0.62: A constant value used for conversion.

IE: Irrigation efficiency.  Some irrigation water never gets used by the plant, this value compensates for that.  I suggest using 0.75 as the value for this.  Very well designed sprinkler systems with little run-off that using efficent sprinklers can have efficiencies of 80% (use 0.80).  Drip irrigation systems typically have efficiencies of 90% (use 0.90).

Example:
A 1500 square foot grass lawn in zip code 85232 (Central Arizona)
Start by looking up the Eto for zip code 85232 at the Rainmaster website, which displays a suggested reference value of 0.3 inches per day using June, the driest month of the year in that area.

Now rewrite the formula inserting your values into it:

0.3 (Eto value)  x  1.0 (grass value)  x 1500 (sq ft)  x 0.62 ÷ 0.75 (efficency factor) = gallons of water per day

Now do the math, just punch the values into a calculator and get your answer:
0.3   x   1.0   x   1500   x   0.62   ÷   0.75   =   372 gallons per day



We could figure out the average daily water use for other months of the year also.  Just use the same formula but insert the Eto value from the Rainmaster website for the month you want to get a valve for.

Remember this calculation just gives you an estimated value.  There are many other factors that could make this value higher or lower.  When planning for how much water a system that has not yet been designed or installed will use, it would be very wise to allow for  error by adding 10% or more to the daily water use needed.  It is generally better to have too much water, than to have too little!  Play it safe!

A common related question is “how much water pressure will my irrigation system need?”  The answer depends on a lot of factors, but as a rule of thumb, I would suggest 50 PSI of water pressure as a good starting point for sprinklers, 45 PSI for drip systems.  If you have a large yard and want to put the sprinklers farther than 30 feet apart you will need more pressure.  For example, if you want your sprinklers 45 feet apart you will probably need 65 PSI of water pressure.  To get a real value you will need to create an actual sprinkler system design. See the Landscape Sprinkler Irrigation System Design Tutorial .

Never buy a pump, sprinklers, or any other materials before your sprinkler design is completed!

Drip tube blows off fittings.

Q:  The pressure is blowing off the pipes/tubes from the barbed fittings on my drip irrigation system.  This is only happening on hot days (30°C=86°F in the shade).  Pipe temperature could be as high as 45°C=113°F.  Our water pressure varies between 2.5 and 3.1 bar (35 and 45 PSI.)

A:  Drip tube should not blow off the barbs, even on a hot day when the temperature softens the plastic tubing (however the heat does make it easier for them to blow off!)  There are three common reasons the tubes blow off.

1. The most common problem is that the water pressure is too high.  This is probably your problem.  The water pressure should be around 1.3 to 2.0 bars (20 – 30 PSI).   You should install a pressure reducer after your valve to lower the pressure.

2.  The pipe and fittings may not be the same size.  This is one of the pitfalls I warn about in my Drip Guidelines.   16mm and 18mm tube  are both commonly referred to as 1/2 inch in the USA! The fittings for these two are not interchangeable.

3. Pressure spikes can pass through the less expensive pressure reducers often sold for drip systems.  If you have high water pressure this may be the problem.  The solution is to install a high quality brass pressure reducer valves.  These generally are sold in the plumbing department rather than the irrigation department of stores and cost $50.00 or more.

Common sizes are 12 mm (0.455″ or 3/8″), 16mm (0.620″ or 1/2″), 18mm (0.720″ or 1/2″), and 24mm (0.940″ or 3/4″). Do you see the problem? Two sizes are commonly referred to as “1/2 inch” in the USA! The fittings for these two are not interchangeable.

Drip emitter installation tools.

Q:  Have you come across tools to insert drippers in tubes or pipes?  Pushing the dripper’s into the tube is leaving my fingers bruised.

A:   You’re right, some of the hole punches are better than others.  I have one that has a nice big grip handle on it that is easy to hold.  But another inexpensive hole punch I have simply has a rounded top that you press with your palm to force the punch into the tube.  It makes your palm sore after just a few uses.  Pressing the emitters into the holes can be a pain too.  Inserting a couple dozen emitters into the holes can leave your finger tips hurting!  Some emitters have irregular, rough, or sharp edges that make it even worse.

Fortunately there are many tools made to help you out.

There are any number of simple hole punches.  Some are small and hard to hold, some have larger handles which makes them a bit easier.  All of these are very simple tools, you hold them in your hand and press a sharp tip through the wall of the tubing, a bit like an ice pick would work.  Actually an ice pick would work to make a hole, however I have found that any type of pointed punch tends to be too aggressive; it punches a hole through one side of the tube and out the other, making two holes!  Then you have to put a goof plug in one of them to plug it up.

Another thing to consider is the shape of the hole punched.  Most punches actually create a round hole about an 1/8″ in diameter.  Some create holes as large as 1/4″ for specific brands of emitters with larger barbs.  It is much easier to get the emitter into a round hole than one made with a pointed tip, such as a nail. When holes are made with a pointed tip the plastic tube tends to stretch as the tip goes through it.  Then the hole closes back up when you pull the tool out, the resulting small hole is hard to get the emitter barb into.  Also a pointed tip is more likely to tear the tubing wall as the tubing stretches around the tool, creating something more similar to a slit than to a round hole.  There is some debate as to if these tears in the tubing will enlarge over time (similar to how a tear in a plastic bag sill get larger if you pull on it.)  I tend to think you are better off with a round tipped punch that punches an actual round hole in the tube, as opposed to a pointed tip.

Note that any punch that you hold with your finger tips, or press a small “knob” with your palm to operate, is going to be hard on your fingers or palm if you install more than a dozen emitters at a time.  These super cheap punches work fine for a few emitters, but beyond that… ouch!

There are more sophisticated hole punch tools, like the Miracle Punch.  It holds the tube firmly in place which aligns the hole properly.  It operates similar to a pair of pliers, which is much easier on your hands.  There is at least one other “pliers type” tool I have seen on the market, however it does not hold the tubing as firmly.

There are a number of devices made to install the emitters.  Most of these are product specific, that is they only work with a particular brand and model of emitter. They generally have a handle on one end and a molded cradle that you place the emitter in on the other.  You place the emitter in the cradle and then press it into a hole you have already punched in the tube using a hole punch.  Some of these device have both the hole punch and emitter insertion cradle as part of the same tool.

Some companies, like Rainbird, make emitters that are “self punching”.  The barb on the emitter is sharp enough to create it’s own hole when pressed hard against the tube.  Rainbird makes a tool that you place the emitter in, then using the tool you press the emitter into the tube.  My experience is that you need this tool to use the self-punching feature of the emitter.  Without it I have not had much success getting the emitters lined up correctly and pressing them in with your fingers is near impossible.  You don’t have to use the tool to insert the Rainbird emitters, it works fine to punch a hole first using a punch and then stick them into the hole.

TIP: Try wearing heavy leather gloves when installing the emitters to reduce hand pain.  Also try putting a couple of pieces of cardboard in your palm between the hole punch and your hand, to help distribute the pressure over a larger area of your palm.