The Basic Parts of a Drip System

Filter checkup at Igingilanyi Village drip system- Iringa

Illustration of a very simple drip system

Hellow, welcome to Water Droplet Community. To day I would like to present to you basic parts of Drip irrigation system with their general management. Simple language have been used to equip easy understanding . You are welcome.

Valves:

Valves turn on or off the water flow through a pipe.

Isolation valves are manually operated valves used for infrequent shut-off of the water. Typically an isolation valve is located at the water source so the water can be shut off for repairs or shut off during the non-irrigation season. Isolation valves may also be installed anywhere on the irrigation system to allow the shut down of sections for repair, this is common on large systems where shutting down the whole system for a repair would be inconvenient.

Control valves are the valves that turn on and off the water to individual “circuits” or areas of the yard that are irrigated separate from one another. The control valves can be automatic (usually electric-powered using a solenoid) or manually operated (hand-powered, ie; turn, turn, turn!) There may be just one control valve or there may be several control valves on a drip irrigation system. For example one control valve may turn on and off the water to emitters/drippers in a vegetable garden. Another control valve might turn on and off the water to emitters for some hanging pots on a patio. Another control valve might turn on and off the water for the emitters at shrubs around the house. Another could even turn on and off water for sprinklers in the lawn, or water for filling the swimming pool or pond. For more information on valves for drip systems, click here

Backflow Preventer:

The backflow preventer is a device that prevents dirt, salmonella, dog pee, etc. from being sucked back into your drinking water from the drip system. You need to use a backflow preventer on ALL drip systems. No exceptions! For more information on backflow preventers, why you need one, and a simple guide to which type to use, see the page on backflow preventers- click here

Pressure Regulators and Pressure Reducing Valves:

A pressure regulator reduces the water pressure and keeps it at a constant level. A pressure reducing valve is another name sometimes used for a pressure regulator, both are the same thing.Most drip systems operate best at lower water pressures than are common in a typical water supply system. A pressure regulator is used to lower the pressure and then keep it at that pressure, even if the incoming water pressure varies up and down. You probably will need to install a pressure regulator on your drip system if your water pressure is higher than 2,8 bars (40 PSI). Keep in mind that a pressure regulator only reduces the water pressure. It will never increase the water pressure, so if you don’t have enough water pressure a pressure regulator will cause you to have even less!

While the name sounds similar, a “back-pressure valve” is not a pressure regulator and has a different purpose.There are two general types of pressure regulators used, non-adjustable ones (with a factory pre-set outlet pressure) and ones with user adjustable pressure settings. Either type may be used for a drip system. As a general rule the non-adjustable type are used for small homeowner drip systems that utilize less than 3 control valves.

 Those people who want the best of everything, regardless of cost, would want to use the adjustable-type pressure regulators, as they allow more flexibility and are usually more accurate.Inexpensive, non-adjustable-type pressure regulators (see photo below) are most often used for simple home drip systems. They are typically made of plastic and have a pre-set outlet pressure. They often have very specific flow ranges and will not work if used at flows higher or lower than the listed range. Since they are not adjustable, be sure to buy the correct one for the flow and pressure your drip system needs.

 The non-adjustable-type regulators must be installed AFTER the control valve, so if you have more than one control valve you will also need one regulator for each of the control valves. If a valve is installed after a non-adjustable-type pressure regulator it can result in a pressure surge that can damage your drip system. It has been my experience that when used on systems where very high water pressures are present some of the non-adjustable-type regulators may allow a quick pressure surge to pass through just after the valve is opened. If you experience problems with drip tubing blowing out of the fittings right after the control valve is opened you may be experiencing this problem. Try switching to an adjustable-type pressure regulator.

Add cNon-adjustable-type pressure regulator.

(Install after control valve.)

Notice this regulator has pipe threads. See the section below on pipe vs. hose threads.aption

The classic adjustable-type pressure regulator can go before or after the control valve. This type of regulator is most often made of brass or bronze, (some plastic versions are made) and has a large screw on it that is used to adjust the outlet pressure. The adjustable-type pressureregulator you use needs to be the correct size as rated by the manufacturer for the flow range. Unfortunately the sizing formulas they provide are somewhat difficult to understand. As a general rule a 50mm (3/4″) adjustable-type pressure regulator will work acceptably for drip systems designed using the Drip Irrigation Guidelines on this website, provided the regulator is set to reduce the pressure by at least 1,4 bars (15 PSI). It is common for the pressure regulator to be a smaller size than the pipe it is installed on. Adjustable-type pressure regulators are often found in the plumbing department of hardware stores rather than with the irrigation supplies.The adjustable-type pressure regulators may be installed either before or after the control valves, whichever you prefer. On larger drip systems, with multiple control valves, the valves are often grouped together in one or more locations and a single adjustable-type pressure regulator is installed on the mainline before all of the valves in a group. This cost-saving measure allows a single pressure regulator to be used for several valves.

To operate accurately the adjustable-type pressure regulators require a pressure drop between the inlet and outlet of the regulator. The amount of pressure drop varies depending on flow, at low flows less drop is required. As a general rule most regulators will work well if you set the pressure at least 1,4 bars (15 PSI) lower than the inlet pressure. If the pressure drop is less than required, the regulator tends to not work as accurately, and may allow the pressure to vary up and down considerably.

Brass adjustable-type pressure regulator.
The large silver bolt on top is turned to change the outlet pressure

Using a Valve as a Pressure Regulator:

Can I reduce the pressure by partially opening the control valve and not use a pressure regulator? This is a common question, and the answer is yes, you can. If the water pressure from your water source does not fluctuate, and the temperature of the valve does not change, a partially closed valve will work just fine. A pressure regulator is nothing more than a valve with a pressure sensor attached to it. The sensor opens and closes an internal valve in the pressure regulator to keep the pressure at the outlet constant. So yes, you can use a partially closed valve to reduce the pressure, however you need to be aware of the problems this can cause. Sometimes the vibration of the water passing through the valve will cause the valve to open or close a little over time. The biggest problem occurs when the water is warmer or colder than the valve. 

The valve will change temperature as the water goes through it and expand or contract, this results in a change in how much water goes through the valve, and that changes the water pressure. If the valve closes due to vibration or temperature change the pressure may be reduced to the point the drip system stops working correctly and the plants don’t get watered. If the valve opens too far the water pressure will be too high. This results in emitters popping out of the tubes and tubing sections blowing apart at the fittings where they connect together. Often when the tubes blow apart they whip around, spraying water all over the place. The worst situation is when there is an open window nearby and the water sprays into the house through the window! So if you are willing to live with those risks, you can use a standard valve in place of a pressure regulator. All you do is open the valve slowly until the pressure desired is obtained downstream of the valve, then leave it at that setting. I suggest periodically checking the valve and water pressure to make sure it has not changed.

Filter:

The filter cleans the water. You should use a filter. Some companies tell you their products don’t need a filter when used with city water, or that it is optional. Optional at the expense of your future time and money! Save yourself dead plants and lots of grief and just install a filter. Drip emitters have very small openings that are easily clogged. Water piped to your house is not free from stuff that will clog your emitters! It contains small grains of sand, bits of rust and scale from pipes, even very small snails (the size of a grain of sand) are very common in city water systems.

I suggest that you use a filter with a 150 mesh screen or one with a higher mesh number like 200 mesh. A good quality filter may be installed before the valve or pressure regulator, but the inexpensive filters often sold for drip systems should be installed after the pressure regulator. A good filter will have a maximum pressure rating of 10,3 bars (150 PSI) or higher. If the package does not list the pressure rating it is probably an inexpensive low-pressure model.

I like to use a top quality filter and install it right at the water source so it protects the control valves and the pressure regulator too. Most valve failures result from sand or rust particles clogging the tiny passages inside the control valves! As long as you need to use a filter, why not get a good one and have it protect the valves too? It will probably pay for itself within 5 years by preventing a valve failure! Use a filter that is the same size as, or larger than, the valve. For more information there is a separate, free, tutorial on filters. Click here for the Filtration Tutorial.

Emitters:

The emitters are what controls how fast the water drips out onto the soil. Most emitters are small plastic devices that either screw or snap onto a drip tube or pipe. Some models are preassembled as part of a tube. The most common emitters sold emit 4 liters/hour (4,0 l/hr) of water. That’s about 1 gallon per hour (1 gph). There are many different types and brands available, they each have advantages and disadvantages listed in the detailed page on Drip Emitters. Click here for detailed information on what type of emitter is best for your drip system.

Drip Emitter on a tube
(If you guessed the plants are strawberries, you guessed correct!)

Mainline:

The mainline is the pipe that goes from the water source to the control valves. In the illustration of a very simple drip system above the gray colored vertical pipe under the valve is a very short mainline. The mainline pipe may be made of galvanized steel, copper, SCH 40 PVC, SCH 80 PVC, Cl 315 PVC, Heavy Wall Polyethylene (SDR 7 or SDR 9) or PEX. PVC is damaged by sunlight and should be buried or protected. Apply several heavy coats of paint or wrapping PVC with aluminum tape if it is above ground. Polyethylene has a low burst pressure and should only be used for mainlines where local conditions are appropriate and water pressures are lower than 3,5 bars (50 PSI). PEX pipe is a special type of polyethylene made for use with higher pressure, often sold as a replacement for copper tube. It may be used for a mainline, however, be aware that due to a much smaller inside diameter it has poor flow qualities when compared to copper. I recommend that when using PEX you use one tubing size larger than you would use for copper tube. 

On large drip systems a single mainline might lead to several control valves located at different areas of a yard. On large properties a mainline will be install in a loop around the perimeter of the property. Because the water in the mainline is always pressurized, hose bibs are often installed on the mainline. On a large property with a looped mainline hose bibs are often installed on the mainline at 30m intervals (100 feet) around the property to allow for use of hoses. I like to foliar fertilize my plants using liquid fertilizer from a hose-end applicator, and the hose bibs make this easy. 

There are also devices called “quick coupler valves” that are essentially a water outlet that is mostly underground. You plug a special coupler with a hose attached to it into the quick coupler valve. They are typically only available from on-line retailers or local irrigation specialty stores. I use them in most of my commercial irrigation systems, the maintenance folks love them.

Lateral and/or Sub-Main:

The lateral is the pipe located between a control valve and the drip tube. Some people use the name “sub-main” for this same pipe. I used the term sub-main in the first version of these guidelines, but have decided to use lateral now to avoid confusion with the names used for sprinkler systems. The lateral pipe may be PVC, PEX, or polyethylene. The lateral is located after (downstream) of the pressure regulator so it is not necessary to use a pipe with a high pressure rating. Class 200 PVC or standard “polyethylene irrigation pipe” work good for laterals. Class 125 PVC may also be used but be careful as it breaks easily. PVC is damaged by sunlight and should be buried or protected. Apply several heavy coats of paint or wrapping PVC with aluminum tape if it is above ground. Many small drip systems do not have laterals, in those systems the drip tube connects directly to the control valve. 

The illustration of a very simple drip system at the top of this page shows a system without a lateral. Laterals are often used when multiple drip tubes are needed, such as when the irrigated area is too large for a single drip tube. For example a single lateral or multiple laterals might extend from a single control valve to several drip tubes located in different areas of a yard.

Hose Threads vs. Pipe Threads:

Two different thread types are typically found on 3/4″ drip equipment. Hose threads are the type of threads found on garden faucets and garden hoses. The female side will have a soft hose washer in it to seal the connection. Typically they also have a swivel device on the female side, but not always. Pipe threads are the type of threads found on standard pipes. It’s really confusing, unfortunately, and it is not easy for someone without experience to just look at the threads and tell them apart!

How to identify hose threads: If there is a washer inside a 3/4″ female fitting that is a pretty good sign it is a hose thread. (Although there are some specialty fittings that use washers and have pipe threads. For example; sink water supply hoses.) When looking at male threads, hose threads have threads that are slightly larger and are farther apart from each other. 

There also tend to be a smaller number of threads when hose threads are used and the threaded section of the fitting tends to be shorter. (See photo below.) If you look at male pipe threads you will notice there is a slight taper to the threaded area, the end has a slightly smaller diameter than the back (look real close at the male threads on the left side in the photo below, you can see the diameter increases slightly as you move toward the right.) This works a bit like a tapered cork for a bottle. The taper forces the male pipe threads to bite into the female pipe threads, helping seal the joint as you tighten the connection.

Connecting hose threads to pipe threads: It is best to use a special adapter made to connect them. When you try to connect hose threads directly to pipe threads, it will start out fine and will seem like they fit. But once you get past a couple of full turns you will feel considerable resistance because the threads don’t match. Sometimes with plastic fittings they can be forced together, but most often if you do this the connection will leak (if you force them together there is a good chance of causing unrepairable damage!) A trick that sometimes works for a quick fix when connecting a hose thread to a pipe thread is to put two washers in the joint rather than one. A much better way is to use a special adapter made for the conversion (see photos of adapters below.)

Hose to pipe adapters: They make adapters that have hose threads on one side and pipe threads on the other. They are available in many combinations: male hose to male pipe, female hose to female pipe, as well as male to female versions. There are also versions that convert to 1/2″ pipe threads rather than 3/4″. Any good hardware store should have at least a couple of these combinations available. A good suggestion is to “mock up” your connections by screwing them together slightly in the hardware store before you buy the parts. That way you know they will fit. To help you read labels, common abbreviations used in hardware stores are

•     MHT = Male Hose Thread
•      FHT = Female Host Thread
•      MPT = Male Pipe Thread
•    FPT = Female Pipe Thread
•    Pipe = Pipe Thread
•   Hose = Hose Thread.                                                                                                                                                                                                                                                                 Remember to use Teflon tape sealer on male pipe threads to prevent leaks. Avoid liquid pipe thread sealants on irrigation systems, excess sealant breaks loose inside the pipe and clogs the emitters and sprinklers. You don’t need Teflon tape on hose thread connections, they should have a hose washer that seals them.

Pipe Thread to Hose Thread Adapters
Pipe threads are on left, hose threads on right
Top is a MPT x MHT adapter, bottom is a FPT x FHT adapter

Drip Tubing (Drip Hose):

Drip tubing is a special tube used in most drip systems. The tube is laid on the ground surface between the plants. The emitters are installed on this drip tube. Drip tubing is a thin-wall polyethylene tube (thinner than standard polyethylene hose), has a low pressure rating, and is generally produced in metric sizes. Sometimes it is called drip hose or drip pipe. 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. So make sure you know what you’re getting when you buy it! Do not bury drip tubing underground- gophers and moles love to chew on buried drip tubing! Some drip systems do not use drip tubing. 

These systems are commonly called “hard-piped drip systems” and are used mostly for very high quality drip systems in commercial landscapes. On a hard piped drip system the emitters are installed directly onto the laterals. This requires special emitters with threaded connections rather than barbs. For a drawing showing how a hard piped emitter works click here.

Drip Tube Fittings:                                                                                    

Fittings (including tees, couplings, ells, and adapters) are the plastic connectors used to attach the drip tube to other tubes, to control valves, or to pipes. Important- make sure the fittings are the exact right size! Using fittings made for a different tubing size will result in the tube blowing out of the fitting. 9 times out of 10, when a tube blows out of a fitting it is because the fitting is the wrong size. If you use a 15mm fitting on 16mm pipe you are going to have problems. Remember, both 15mm and 16mm tube are often labeled as 1/2 inch size in the USA!

Barb type fittings insert into the drip tube. Generally they should not require the use of a hose clamp to hold them on, if a clamp is needed the water pressure is too high or the fitting is the wrong size. The advantage of barb fitting is that they are generally easier to install than the compression type. The disadvantage of the barb type is that as the tube goes over the barb it is stretched, which weakens the tube. The weakened tube will sometimes split open at the barb after a few years, especially if exposed to sunlight. OK you ask, if barbs are a problem then why do they use barbed fittings with standard polyethylene pipe? Standard poly pipe has a much thicker wall than drip tube and doesn’t stress as much when stretched. 

You also clamp standard poly pipe to the fittings, which helps keep the pipe from splitting (that’s why you need to clamp poly pipe even if it seems to stay in place without the clamps). Drip tubing is not clamped to the fittings (clamping doesn’t help prevent splitting because of the thin drip tubing wall).

Compression type fittings are basically the reverse of a barb fitting. The tube slides inside the fitting, where an internal barb compresses the tube and holds it in place. The advantage of compression fittings is that they do not stretch the tubing, so they are not a cause of premature failure of the tube. Once the tubing is inside a compression type fitting it is very difficult to remove.As a general rule, barb fittings are best used for buried or covered tubing (the tube is not exposed to sunlight) and compression fittings are used for tubing that is not buried.

Drip Tube Fittings
Left: Barbed Type Right: Compression Type

Lubrication: Some people just don’t have the strength to shove the tubing into a compression fitting. First make sure the fitting is the right size, as that is very often the problem. If it is, then you can use a water soluble lubricant on the tube. Do not use oil, silicon sprays (WD-40) or soap! Absolutely do not heat the tube with a flame, hair dryer, or hot water as that will stretch the tubing and create weak spots! What’s a water soluble lubricant? Try a product called K-Y Jelly. Attention guys! Avoid terminal embarrassment! Do not head for the hardware store for K-Y Jelly. Try the drug store, err, lady’s personal hygiene department. Might want to take along the wife. Need I say more?

Spaghetti, Feeder, and/or Distribution Tubing

Feeder Tubes, Spaghetti Tube, and Distribution Tubing are all names used for small diameter poly or vinyl tubes, anything less than 10mm (3/8 inch) in diameter. I love spaghetti to eat, but I hate it for use in drip systems! The problem with these small tubes is with maintenance. These little tubes tend to be easily cut, broken, pulled loose, etc. and are generally a nuisance. This small tube is often connected to the outlets of multiple-outlet emitters. This tubing is the reason I do not recommend the use of multiple-outlet emitters. 

If you are a meticulous type person who can be very careful, do your own yard maintenance, and you don’t have pets or kids in the yard, you may not have any problems. But for most of us, regret soon sets in as repairing these small tubes becomes a weekly maintenance chore. There are a couple of exceptions where the tubes work well. One is when they are stapled above ground to a trellis or arbor for watering hanging plants. They need to be firmly attached, in a location where they will not be damaged. The other is for risers used on hard-piped drip systems.

Air Vent:

The purpose of an air vent is to prevent air from being sucked into the emitters when the system is turned off. When the drip system is turned off the water in the pipes drains down to the lowest point, where it drains out of the emitters. As the water drains out it is replaced with air that is sucked into the tube through the higher emitters. As the air is sucked in, dirt may also be sucked in with it. The dirt may then get stuck and clog the emitter outlet. The purpose of the air vent is to allow air to be sucked in through the vent rather than the emitter. 

When used, the air vent is installed at the highest point on the drip tube. It is important to make sure that the air vent will not become covered with dirt or dirty water as that would allow dirt to be sucked into it. Always use air vents if the drip system is installed on a slope, as the elevation change creates a more powerful suction that will suck in more dirt. Air vents often are not used on smaller drip systems. If you don’t use them just make sure the highest emitters aren’t sitting where dirt can easily be sucked into them.

A small air vent designed for a drip system

Flush Valve or End Cap:

The end cap is important. Without it the water all runs out the end of the drip tube. (Well, duhhh…) The water in a drip system flows very slowly in the tubes. This allows any sediment in the water to settle out, over time a layer of this sediment develops inside the tube and needs to be flushed out. In some climates algae may also grow in the tubes and need to be flushed out periodically. Normally drip tubes are flushed once a year. If you have algae problems you may need to flush the tubes more often.

 Automatic flush valves are available that flush the tubing each time the water is turned on. I do not feel that most of these are particularly effective. They simply do not flush for long enough or flush enough water out to remove much, if any, sediment or algae. My preference is to use a manual flush valve, or just use a simple hose-thread cap that you can remove to flush the tube. Here’s a money saving tip; you can make a end cap/manual flush valve by just bending over the end of the drip tubing on itself to crimp off the flow. Then use some wire or a cable/zip tie to hold the tube in the crimped position. Un-crimp and straighten the tube when you want to flush it.

Tubing end crimped with a cable tie

For very high end drip systems with lots of algae or sediment you may want to build your own auto flush unit. This is an expensive project requiring a high level of skill and knowledge! Manifold the ends of the drip lines together, so that a single flush outlet can flush the entire drip circuit. Install a anti-contamination type solenoid valve as the flush valve on the end of the flush manifold. (An anti-contamination valve is a special irrigation valve made for use with dirtier than normal water.) Wire the flush valve to an irrigation controller and program it to open the flush valve on a periodic basis, typical might be for 2 minutes once a week. The drip circuit control valve must also be on during the flushing. So both the control valve AND the flush valve must be activated at the same time.

 Do not wire them together on the same controller circuit as that will cause the flush valve to remain open all the time. You will either need to use two controllers and then coordinate the times on them, or you will need a controller that can run two valves on two different programs at the SAME TIME. Warning; most irrigation controllers can’t do this. I suggest you take these instructions and go to a professional irrigation dealer and have them assist you in your controller selection. Make sure you have someplace for the flush water to go, as it will release a lot of waste water when the flush valve opens. Keep in mind that both anti-contamination valves and the special controller you need to use are expensive and this is not a very cost effective solution in most cases.

Drip laterals for onion nursery -Igingilanyi village, Iringa

Drip lateral foe Chinese cabbage, Igingilanyi village-Iringa

Eng Herman Nguki wa Malekela, (Irrigation & Water Resources)

ngukiherman@ymail.com

0763 639 101/0679 639 101

@Water Droplet Community (WaDCo Tanzania)

Thank you very much for visiting our blog, for questions you are welcome. You are invited also to visit our Facebook page (Water Droplet Community Tanzania). Eng Nguki

DETECTING UNDERGROUND WATER BY DOWSING

A cross-section of a building site above sedimentary materials. The blue line marks the subsurface location of the water table. Wells drilled throughout the area will penetrate the same materials and have a high probability of yielding water.

Dowsing as a Method of Finding Underground Water

Many people believe that dowsing is a valid method for finding groundwater, but most geologists and hydrologists disapprove of the practice.

What Is Dowsing?

 

“Dowsing,” “water witching,” “divining,” and “doodlebugging” are all names for the practice of locating groundwater by walking the surface of a property while holding a forked stick, a pair of L-shaped rods, a pendulum, or another tool that responds when the person moves above a location that will yield an adequate flow of water to a drilled well.

People who practice dowsing believe that groundwater moves in subsurface seams, veins, or streams that must be intersected by the drill to produce an adequate flow of water. They believe that locations where this water is present are surrounded by forces that will produce a response in their tools. Forked sticks held in front of a dowser will be deflected toward the ground, a pair of L-shaped rods held lightly in the dowser's hands will cross one another, and a pendulum suspended on a string will deflect from vertical as the dowser moves over a good location. 

Video: How to detect underground water by dowsing

Why Do Landowners Hire Dowsers?

 

Drilling a water well can cost thousands of dollars. It is a major investment that many landowners are hesitant to make without professional consultation. They want to be sure that the well is drilled in a location where it will produce water of adequate quantity and quality. This is why many people hire a dowser. They want to drill a successful well, close to their house, where the cost of installing water lines and an electrical conduit will be minimal and where a drilling rig can be easily driven. 

What Do Hydrogeologists Think of Dowsing?

 

Although some dowsers have a record of regularly producing good results, the United States Geological Survey reports that most geologists and hydrogeologists disapprove of the practice of dowsing . The National Ground Water Association, in a position statement, “strongly opposes the use of water witches to locate groundwater on the grounds that controlled experimental evidence clearly indicates that the technique is totally without scientific merit”.

The Nature of Underground Water

 

Most fresh groundwater occurs in the pore spaces of sedimentary rocks and sediments. It has the ability to flow laterally through these pore spaces and establish a “water table” that is generally horizontal or slightly sloping. If a landowner wants a well drilled within a hundred or so feet of a building site, almost any location selected will have similar potential for yielding water to a well. Why? Because the same types of rocks are usually present beneath that small area. 

Locating and drilling into a good water supply can be difficult in areas underlain by igneous rocks such as granite and basalt. These rocks do not contain pore spaces through which water can flow. Instead, the water must move through very narrow fractures in the rock. A well must intersect enough of these tiny fractures to produce useful amounts of water. It can be very difficult to drill successful wells in some areas underlain by thick cavernous limestone. In these areas, wells that do not intersect a fracture or a cavern might not yield abundant water. 

Regarding these igneous and limestone areas, geologists and hydrogeologists believe that there is no scientific basis for a dowser or a dowsing tool to have the ability to select a location where a drilled well will intersect subsurface fractures or small caverns. 

How Do Hydrogeologists Locate Water?

Most successful water wells are drilled without the advice of a hydrogeologist. Local drilling companies often have the experience of drilling hundreds or thousands of wells in the areas where they operate. They have learned through this experience the parts of their service area where wells with adequate amounts of quality water are usually encountered. They also know areas where locating an adequate water supply can be challenging. 

If a hydrogeologist is called to determine a suitable drilling site, he or she will start by examining a geologic map. These maps show the types of rocks that exist below the landowner’s property and their direction of dip. They also provide information about the different types of rock units that exist in the area. Some types of rocks are known to be good producers of water, whereas others will not hold or yield useful water. 

The dip of the rock units and the topography of the area can be studied to identify the direction of groundwater flow, potential water recharge areas, springs, and discharge points. The depth of impermeable rock units can sometimes be determined, and these can serve as a lower limit for drilling. All this information allows the hydrogeologist to develop a three-dimensional model of the property that might define locations that are promising or those that should be avoided. 

The hydrogeologist will also seek information about previous wells drilled in the local area. Most drillers maintain a file of the types of rocks penetrated and the amount of water produced for each well that they have drilled. This information is very useful in determining the probability of drilling success on a nearby property. 

Hydrogeologists often examine aerial photos when siting a well in a challenging area. Aerial photos often reveal linear features that might indicate the presence of fracture zones in the bedrock. These areas often yield abundant water to wells. 

Using the information described in the studies above, hydrogeologists base their recommendations on 

1) the characteristics of the land;

 2) characteristics of rocks beneath the site;

 3) results from previous drilling; and, 

4) known principles of groundwater movement. They believe that this type of information is more useful for siting a well than how a stick, a wire, or a pendulum responds to an unknown force 

Conclusions

 

Many successful wells are drilled without the cost of a dowser or a hydrogeologist. The driller often has a lot of experience in the area being drilled and knows if the rocks in that area typically yield useful quantities of water. 

When professional consultations are required or preferred, the landowner must make a decision. Should the project costing thousands of dollars be based upon scientific information about the rocks beneath a site, their water-yielding properties, and known principles of groundwater flow; or, should it be based upon a forked stick and an unexplainable force? 

By Eng. Herman Nguki. (Irrigation& Water Resources)

WaDCo Tanzania E- Director.

Cont: 0763639101/0679639101/ ngukiherman@ymail.com

Contributor: Hobart King 

I hope you have enjoyed the lesson. Eng Nguki will soon bring to you more videos and demonstration practicals on dowsing and other issues as per for WadCo mission and vision. Welcome

References

[1] Water Dowsing: A general interest publication by the United States Geological Survey; 1988. 

[2] Water Witching: A position paper by the National Ground Water Association; August 2009. 

[3] How Do Hydrologists Locate Groundwater?: Article on the United States Geological Survey website; last updated March 2014. 

[4] Ground Water in Fractured Hard Rock: A “Water Facts” publication of the California Department of Water Resources; April 1991. 

[5] De Re Metallica: Georgius Agricola, published posthumously in Germany in 1556. 

Agricultural Pollution

Drinking polluted water  from agricultural chemicals is dangerous

Developing means of farming and agriculture is the reason humans live in the world they do today. It is a necessary means of survival, without which there would be famines all over the world. For thousands of years, agricultural was a natural process that did not harm the land it was done on. In fact, farmers were able to pass down their land for many generations and it would still be fertile as ever. However, modern agricultural practices have started the process of agricultural pollution. This process causes the degradation of the eco-system, land and environment due to the modern day by-products of agriculture.

No single cause can be attributed to the widespread agricultural pollution we face today. Agriculture is a complex activity in which the growth of crops and livestock have to be balanced perfectly. The process of agricultural pollution stems from the many stages their growth goes through.

Spray of agricultural chemicals pollute environment, surface and underground water

Causes of Agricultural Pollution

1. Pesticides and Fertilizers: 

To begin with, the earliest source of pollution has been pesticides and fertilizers. Modern day pesticides & fertilizers have to deal with the local pests that have existed for hundreds of years along with the new invasive species. And so, they are laden with chemicals that are not found in nature.

Once they has been sprayed, it does not disappear completely. Some of it mixes with the water and seeps into the ground. The rest of is absorbed by the plant itself. As a result, the local streams that are supplied water from the ground become contaminated, as do the animals that eat these crops and plants.

2. Contaminated Water: 

Contaminated water used for irrigation is one further source of pollution. Much of the water we use comes from ground water reservoirs, canals and through the rains. While plenty of it is clean and pure water, other sources are polluted with organic compounds and heavy metals. This happens due to the disposal of industrial and agricultural waste in local bodies of water.

As a result, the crops are exposed to water which has small amounts of mercury, arsenic, lead and cadmium dissolved in it. The process of agricultural pollution becomes harder to fight when such water poisons the livestock and causes crop failure.

3. Soil Erosion and Sedimentation:

 Further problems are caused by soil erosion and sedimentation. Soil is comprised of many layers and it is only the topmost layer that can support farming or grazing. Due to inefficient farming practices, this soil is left open for erosion and leads to declining fertility each year. Whether eroded by water or wind, all this soil has to be deposited somewhere or the other.

The resulting sedimentation causes soil build up in areas such as rivers, streams, ditches and surrounding fields. And so, the process of agricultural pollution prevents the natural movement of water, aquatic animals and nutrients to other fertile areas.

4. Livestock:

 In the olden days, farmers would keep as much livestock as their land could support. The cattle, sheep, pigs, chickens and other animals were fed natural diets, which was supplemented by the waste left over from the crops. As a result, the animals contributed to keeping the farm healthy as well.

As of now, livestock is grown in cramped conditions where it is fed unnatural diets and sent to slaughterhouses on a regular basis. As a result, they add to the process of agricultural pollution by way of emissions.

5. Pests and Weeds: 

Growing exotic crops and reducing the natural species in a certain area has become the norm for agriculture. However, it is simply adding to the process of agricultural pollution. With the arrival of new crops, the native population has to deal with new diseases, pests and weeds that it is not capable of fighting.

As a result, the invasive species destroy the local vegetation and wildlife, altering the eco-system permanently. This is especially the case with Genetically Modified foods, which create plant and animal species that can wipe out the existing species in a matter of years.

Frequent use of chemicals affect the land productivity

Effects of Agricultural Pollution

1. Health Related Issues: 
Agricultural pollution is the main source of pollution in water and lakes. Chemicals from fertilizers and pesticides make their way into the groundwater that end up in drinking water. Health related problems may occur as it contribute to blue baby syndrome which causes death in infants. 

2. Effect on Aquatic Animals:
 Fertilizers, manure, waste and ammonia turns into nitrate that reduces the amount of oxygen present in water which results in the death of many aquatic animals. Again, bacteria and parasites from animal wastes  can get into drinking water which can pose serious health hazards for various aquatic life and animals.

Keeping agricultural pollution in check is much harder than it seems. For the farms to become clean once again, levels of water, soil and industrial pollution have to be kept in check. Over the last decade or so, governments have become stricter about enforcing regulations. Farmers are also becoming more aware of the damage and are looking for solutions.

Many farms are moving back to traditional manure, direct irrigation from local water bodies and organic means of keeping pest populations in check. But for the process of agricultural pollution to be fully reigned in, there has to be a complete shift in the way agriculture is practiced.

Eng Herman Nguki (Irrigation and Water Resources) .WaDCo E-Director.

www.wadcotanzania.blogspot.com

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