USING A PUMP FOR DRIP IRRIGATION: COMMON MISTAKES AND BEST SOLUTIONS

One of our most frequently asked questions is, “Can I use your cistern pumps with my drip irrigation system?”

The answer to this question can get a bit tricky because drip irrigation itself is a confusing subject. Three types of irrigation systems get lumped into the “drip irrigation”category, so to answer this question, first we need to know what type of drip system is being used.

DRIP TAPE

First, there is drip tape -- an inexpensive (and usually disposable) flat plastic tape that is designed to work at 10 PSI maximum. Often times, a 10 PSI pressure regulator is required to run drip tape, or else the entire irrigation system is liable to blow apart. 10 PSI is low pressure. In fact, it is much lower than the majority of pumps are able to handle. Every pump has an operating range associated with it —also known as a pump performance curve. It’s a curve because flow (measured in gallons per minute) and pressure (measured in pounds per square inch) are directly related in a pump’s performance. As you increase your demand for flow, you decrease the pump’s ability to build pressure. Likewise, the reverse is true: As you demand an increase in pressure, you decrease your flow rate. For example, our Grundfos SBA 3-45-AW will operate at 52 PSI when the flow being demanded is 5 gallons per minute, and it will operate at 38 PSI when we call for 10 GPM. When we follow the pump’s curve, we see that at 10 PSI (which, again, is the operating pressure for drip tape), the Grundfos SBA will produce a flow rate of 23 gallons per minute! It takes a LOT of drip tape to get to that kind of flow rate. 

So what are the options? Can you use a pump with drip tape systems? 

Yes and no. 

If you stick a Grundfos SBA or a Strom BSP automatic pump in a tank and run it to your drip system, chances are good that you’re going to cause that pump to short cycle constantly…it will detect a flow being demanded by your irrigation system, but, without sufficient flow rates (in this case, 23 gallons per minute), it will be able to build up so quickly to the 10PSI pressure that it will shut off immediately. That’s a quick way to burn up a pump.

There is a solution, though. A traditional drip irrigation system will be set up, in order of flow, as Pump —> Valve (automatic or manual) —> 10 PSI Pressure Regulator —> Drip Tape. If you know you aren’t going to have enough flow being demanded from your drip tape system, the simple solution is to install a “T”fitting after your valve but before your pressure regulator and run a 1/2”or 3/4”or 1”return line back to your water tank. In so doing, you will create a relief port for excess pressure and excess flow generated by the pump, causing it to run less frequently. And, if you bring your return line right into the top of your water tank, you have the added benefit of circulating the water and reducing the likelihood of algae growth. 

DRIP EMITTERS

The second type of drip irrigation system is one that uses drip emitters. Like drip tape, drip emitters typically require low pressure, and they always drastically reduce flow. Unless you are using hundreds of emitters at once, it is not recommended to use a pump to provide water to drip emitters. Instead, we recommend using zero-pressure emitters, such as Flag Emitters, where the pressure created by gravity on an above ground tank is sufficient to provide water to the emitters. 

DRIP TUBING

The third and final type of drip irrigation system is drip tubing. Drip tubing is round and generally has drip emitters embedded every 8-24”. Unlike drip tape, drip tubing can work under pressure…generally as high as 50-60 PSI. Drip tubing works well with our cistern pumps, though, again, you will want to reference the pump’s performance curve to see how much flow you should have in your irrigation system at a given pressure. For instance, if you want to run the Grundfos SBA pump at 50PSI, you need to make sure that you zone out your irrigation system so that each zone is operating at 8 GPM.

Each drip tubing roll will specify the spacing of the emitters and the flow rate of each emitter, so if you are using tubing that has emitters every 12”, and the emitters have a flow rate of 0.5 gallon per hour (tubing is usually measured in gallons per hour, not gallons per minute) per emitter, then you would 960 feet of drip tubing to get a flow rate of 8 gallons per minute and to stay within the operating capacity of the SBA pump. If you don’t need that much drip tubing, then, again, we recommend installing a return line back to your rain tank that can let water freely flow into your tank to bleed off excess pressure/flow.

Colorado Legalizes Rain Barrels

Rainwater collection is now legal throughout the United States. Colorado Governor, John Hickenlooper, recently signed a new law allowing Colorado residents to have two rain barrels on their property, holding up to 110 gallons. It would seem intuitive to many people that rain that falls on your property should be your water to use, should you choose to collect it. However, it had been technically illegal in Colorado for many years based on archaic water laws. The gist of the existing law was that collecting rainwater on your property prevented said water from reaching farmers and other water rights holders.  And in a state like Colorado, where drought is common, a farmers' concern is understandable. However, there are many reasons why allowing rain barrels may be beneficial for both residents and farmers.

Owning a rain barrel fosters a sense of water conservation. When irrigating a garden with a rain barrel, one becomes acutely aware of the amount of water being used and considers efficient ways to water such as drip line or soaker hose kits. When one irrigates from their house spigot, the amount of water being used is harder to quantify, and one is likely to over-water.

This mindset of conservation is what Colorado lawmakers are hoping to to cultivate by passing the new law allowing rain barrels. It is best for the entire community, both residents and farmers, when the general public is cognizant of their personal water-usage and takes steps to efficiently use their water.

Rainwater collection has already become popular in many other states, and is even encouraged by local governments. Colorado may be a little late to the game, but we're glad they're finally here.

Irrigating your Garden from your Rain Barrel

With Spring right around the corner, many people are planning out their gardens. A major component of a future garden plan is figuring out how to irrigate. Installing a Rain Barrel is a great place to start. Not only is it a source for free water, but it is also clear of chemicals, such as chlorine and flouride, that are often present in city tap water. Your plants will thank you for giving them pure water to drink.

Once you have you a Rain Barrel and it's collecting water, the next thing to figure out is the best method to get that water to your plants. Here is a list of irrigation tips to maximize your precious collected rainwater.

Soil Preparation

-Soils may be sandy and gravely which hurts water retention, or they may have high clay content which can retain too much water. Adding organic material such as compost to your soil will help stabilize either extreme and create a moistiure balanced environment for your plants' roots.

-Prepared beds are ideal for root mobility. Individual planting holes can restrict your plants' roots, thus restricting access to water. Take the time to prepare an entire bed and watch your plants flourish.

-Be sure to mulch. Mulch will help hold moisture that would otherwise evaporate and will also help moderate your soil temperature.

Water Where It Matters

-Many people assume that irrigating your garden involves a hose and spray nozzle working with 45-50 pounds of water pressure. However, this is a perfect example of how not to water your garden. First, you will waste a large amount of water. Much of the water coming out the nozzle will not make it to your plants roots. Second, continually soaking your plants' leaves with water puts them at risk for certain fungal disease. Finally, unless you're using a sprinkler, you must stand there and hold the hose, which is precious time you could be doing something else.

-A soaker hose or drip irrigation system is the best method to water your garden. These methods deliver water right the base of the plant (exactly where you want it), getting right to the roots. As opposed to a spray nozzle, you're giving your plants a slow, steady drink of water that will penetrate deep below the roots. This, in turn, encourages the roots to grow deeper making for a healthier plant. It is important when choosing a soaker hose to use with your rain barrel that you choose a soaker hose that works with low pressure systems, such as this soaker hose here. 

A Few Other Tips

-Water when needed. If rain is in the forecast, hold off on watering your garden. Overwatering can decrease oxygen levels in your soil and can cause root rot, killing your plants.

-Water in the mornings. This will decrease the amount of water that evaporates. Also, if you water with a hose and nozzle (which I advise against), this will give your plants leaves time to dry off, decreasing the risk of fungal disease.

-Pull out the weeds! All those pesky weeds in your garden are drinking water that your lovely, food-producing plants could be drinking. Eliminate the competition.

Happy Gardening!