Thursday, June 7, 2012

Water, Accurately Applied When and Where You Want It by Dave Moland

Let’s face it folks – the era of our trying to simulate summer rainstorms when we water our landscapes is over. The “New Age of Aquarius” is upon us, and I’m not referring to astrological eras or meanings here. Aquarius in mythology was “the cup-bearer to the gods”, or the sign of the “water carrier”. We don’t have to water our gardens by carrying water in cups, but now it’s time for us all to apply our water much more wisely and accurately!

Having experienced a very dry March, and seeing the TV news regarding the relatively low mountain snow pack in our watershed areas, coupled with the fast spring melt and a very possible hot, dry summer, I believe that all forms of Water Wise Gardening – including drip watering, use of soaker hoses and minimizing our turf areas, will soon be “mandatory” in many areas of Colorado. Our prolific use of city-system water for overhead sprinkling of large lawns and gardens may soon be priced out of most of our budgets, even if not severely rationed.

Let me appeal to your pocketbooks – I don’t want to pay for water that evaporates, or is not applied where it does the optimum good, do you? Water can be very effectively applied to gardens and pots via low-cost drip systems, and vegetable garden rows can be watered with soaker hoses. This can be accomplished without significant water loss through evaporation if the drip or soaker hoses are placed under your mulch in near proximity to the plants. This also assumes, of course that mulch is already being used in our gardens to keep roots cool, minimize evaporation and reduce weed growth. You all know about mulch, so that’s enough here about mulch. Timers can be used to control the frequency and duration of drip/soaker systems, as we now do with lawn irrigation, so we don’t have to stay home to water our garden by hand – yes, we can go on a summer vacation!

Drip Fittings Figure 2
Drip Fittings
Drip Systems – Many of you Jeffco gardener bloggers are likely familiar with, or are already using, some form of drip system for part of your landscape. Figure 2  shows a simple control system which can be made for a nominal cost and is easy to maintain and use. For watering pots, I prefer the little 1/4” soaker (weeping) hose instead of “spot emitters” or “drippers”, as the little soaker hose can be coiled/positioned to drip over the entire soil surface of your containers, pots, barrels etc., and can easily be cut to length as needed. That’s just my own preference – if you prefer using spot emitters, that’s up to you, but you will have to place each one more accurately. Either way, use something that won’t have to be repositioned when the leaves on your plants grow larger later in the season – as would be required with small spray heads. Lay out your drip system so that each zone (a system section controlled by one valve) can be connected with a minimum of distribution tubing and is at relatively the same height throughout its length.

Soaker Hoses – These are available at any hardware store, big box store or nursery. I prefer the round type, as you don’t have to fuss about trying to make them lie flat, and they are easily adapted to curves. Most soaker hoses have a flow-limiting disk in their inlet coupling. These are “calibrated” to the size and length of soaker hose and a typical water supply pressure, so no other pressure regulator is necessary. When I use a soaker hose on a control system which has it’s own in-line pressure regulator, which regulates to about 25 psi (pounds per square inch), I remove the flow-limiting disk from the hose.

Hillsides and Slopes – More attention is necessary when designing and laying out drip and soaker systems that are to be used on hills or slopes, as slopes can greatly affect the pressure and flow in your watering zones. In general, the drip/soaker tubing should be laid out so that there is a height difference of less than 2 feet in one watering zone – In other words, lay them out across the slope, not up and down the slope. If you don’t pay attention to this, you may find lots of water at the bottom end of a zone, and little or none at the top.
If you use the little 1/4” soaker hose, such as for separate pots, you can compensate for some of this pressure differential by using shorter lengths on the lower segments, but if you have more extreme slopes, you may have to use city water pressure on your main distribution lines on the upslope/downslope, and separate regulators for each horizontal segment of soaker hose or emitter lines.
The number of sections of soaker hose you can use in one zone will be dependent on their length and their porosity.  Alternatively, if your plants are not closely spaced, you may want to use low-pressure distribution tubing with spot emitters instead of soaker hoses on the horizontal segments. Pressure-compensating emitters are also available if the tubing lines cannot be reasonably level. See also CSU Fact Sheet 4.702 for more details regarding slopes and the use of various types of emitters.

Water Supply Pressures – Home water supply pressure usually ranges somewhere between 40 to 80 psi. It can also depend on local water system use at the time of day you water, and also on your elevation relative to the source. Output pressure from in-line regulators for home drip systems is usually in the 20-30 psi range.

Drip Valves and Controls
Valves and Timers – If you want to automate your system, you will need a control valve and a means of setting the ON time and duration for each zone of your drip or soaker system. This may sound a bit complicated, but if you already have a sprinkler system timer for your turf, check your timer to see if any extra watering circuits are presently available. You may be surprised to find 2-3 of them unused. If no extras are available, a separate timer can be purchased with 4-6 circuits for as little as $20. Standard timers for home watering control have 24Vac outputs for valve solenoids (actuators). Make sure your valve timer has enough flexibility and set-ability to allow the number of minutes per circuit and the repeat cycles you may need. Also, if your drip or soaker system is connected directly to your house water system, make sure you use valves that have vacuum breakers, and position them higher than the highest parts of your zones, to prevent backflow when the pressure is removed.

Distribution Tubing (Main Lines) – 1/2” (nominal size) plastic “distribution tubing” can be used for each zone if the pressure is reduced to 25 psi. It is very flexible, not expensive, and is available in 25, 50 and 100 foot rolls. However, be forewarned: There are several slightly-different inside diameters of this tubing. So – make sure your fittings will make a tight fit inside the tubing!  At 25 psi, you will not need clamps on your fittings if they are sized properly. Check the tubing inside diameter with your fittings before you leave the store.  Inside diameters may vary between manufacturers. I use RainDrip 052005P (50’) tubing, or equivalent. With nominal flow rates to my containers, I have been able to make 80-90 foot runs of this tubing without seeing a significant pressure drop. The distribution fittings shown here are also called 3/8” “Funny Pipe” fittings, but remember to check fitting compatibility with YOUR tubing!

“Microtube” (To Each Pot or Container) – This is a very flexible 1/4” plastic tubing which leads from the distribution tubing at one end, and to the little 1/4” soaker hoses, or emitter(s), at the other end. Connections are made using 1/4” “bayonet” type fittings which can be bought singly or in assortments. Tools are available to punch small holes in the distribution pipe for the bayonet fittings. You can use wire weed-barrier cloth “staples” or equivalent (even bent pieces of coat hangers) to keep the small tubing in place in your plant containers. Don’t forget to plug the open ends of your little soaker hoses!  If you use several emitters along a length of microtube, you will need to carefully space these as necessary to each plant or container and experiment with flow rates, or try to calculate the totals. See CSU Fact Sheet 4.702 for help with this.

Maintenance – Keeping your drip system maintained should be relatively easy. If you have sediment in your water, you will probably want to use a canister filter on the system to keep from clogging your emitters. If you use the little 1/4” soaker hoses in your containers, they may need to be replaced after several years if they stop “weeping”. The 1/2” poly distribution pipe is not normally harmed by freezing. Do make sure that your valves, filters and regulators are drained for winter, but – if the lowest spot on each of your zones is a soaker hose or emitter, you will not need to blow out your lines for the winter, as they will be self-draining. For other special or uncommon installations, see CSU Fact Sheet 4.702, and/or other info at the CSU address listed below.

Be aware that some “cut and try” experimentation will be necessary, especially if you have several different sizes of containers to be watered – ranging from different-sized pots to barrels, and soaker hoses for your vegetable garden. Treat it as a hobby… try it, you’ll like it!  Especially when you see your water bill reduced!

Have fun playing “Aquarius”, the cup-bearer or water carrier – drip water your own garden this year!

For more info on general Irrigation Management, see

Gardener Dave

There will be a drip watering system demo at one of the locations on our

Jeffco Master Gardeners Garden Tour 2012

Scheduled for June 23rd

Watch for more information on the tour and stop by the drip demo if you’re interested.