The only real problem with the system you are making is your whole bed is one zone. Different plants need different amounts of water so unless you plant your entire beds with plants that need the same amount of water you will find you will over or under water within beds. Have you looked into Rainbird micro heads. Although they can clog they are unlikely to do so if you install the system correctly in the beginning. One filter for the whole system will keep the heads from clogging. With this type system (using 1/4" tubing to the micro heads) you can adjust water use within the bed. Also I see "gaps" in your planting. With the micro heads on tubing you can move or shut off heads quite easy. The system will cost more upfront but its ease of use and micro managing of your water might be a big plus. The type of system you are trying I have used in landscape planters where all the plants need the same water and the beds would be fully planted year round. Just a thought.

Good luck,
Tom

Thanks for the good advice Tom, much appreciated.

Just now reviewed my post from late last night and noticed all the typos. I had hastily posted and should have corrected them first . . . sorry.

Also neglected to mention my self-imposed budget for this project, which would, being the self-sufficient and frugal gardener I am, be blown away with most proprietary irrigation systems.

I have looked into Rainbird (among others) and considered it's benefits, including flexibility of micro-head emitter placement and greater precision of water control for variable plant needs. It would certainly eliminate many of the gaps resulting from using rigid pipe, an issue I expected to be problem.

How long have you used Rainbird and have you found the need for frequent microhead replacements? This ongoing expense needs to be considered with the total upfront system costs as well.

Also, do you think having separate PVC ball valves at each pipe section/plant row - such as I intend to do, will allow adequate water control? If some plants need more or less water, my thinking is I can simply adjust flow rate or shut off that "zone" entirely. Or, in reality, is this logic flawed?

Perhaps I should reconsider the system, or modify the design with flex-tubing for selected plantings. Thanks again.

Rainbird micro head systems have been around for many years and I have been installing them and other brands for over 15 years. The nice part about the micro heads is they can be adjusted down all the way to off. If you use a pre-filter they rarely if ever need to be replaced and they are cheap. The first install will cost more because of the basic materials (valves, filter, pipe etc.) but after that the upkeep costs are almost zero. Every 5-10 years or so you will need to replace the diaphrams in the zone valves but the heads last and last. Most companies make 1/4" tubing heads and tubing that will fit most companies heads/tubing so you can try different brands till you get one you like.

Good luck,
Tom

Thanks Tom - I'll take that into consideration.

My intent for this post was to hear from others who have direct experience with the design I am planning to install. This concept seemed to be a smart way to go, since everything needed is available off-the-shelf from any plumbing supply outlet.

I certainly have the means for employing a supplier/contractor to install a proprietary drip irrigation system. But with most tasks associated to my interests, I research my options and most always choose the DIY route. Being a self-employed architect, I also enjoy experimenting with custom or hybrid designs.

In part I suppose it suits my desire to remain self-sufficient - and of course, being frugal :). The cost for all components to water a 24' x 40' garden, shouldn't be more than $150, with me doing all labor. Aside from the permanent underground portions, I am also incorporating a mix of slip + threaded joints to enable diversification with each bed and, being in southern New England, easy + quick removal/set up.

Hopefully someone will share their experiences designing/building similar systems using PVC pipe and fittings.

AD,

Just my $0.02, a few items to understand the hydraulics are missing from your system description. I have been advocating this type of system for those whose irrigate from less clean sources with filters and emitters that clog easily(pressure compensated emitters). Is your water source from a municipal supply? What is your pressure and flow rate? what size holes have you drilled in the pvc pipes? What size of pipe are you using(I assume 3/4" mainline to 1/2" laterals)? What is the slope of your beds? What is the length of the beds? Someone had posted a similar system that worked from rain barrel. TP has some good points but his problems can be overcome by having different plants for different rows with different size holes in the pipe spaced at different intervals. The most important factor is soil make up. Is your soil more sand than clay or the other way around. This is the biggest factor in creating the necessary water plume to reach the plants with sufficient water. TP's recommendations provides the most calculated control(absolute control of hydraulics by the manufacturer) if your source is very clean. You just provide the proper pressure and flow rate from a very clean source. I also believe, if you have the money, TP's recommendation is the most value oriented, water saving, easiest to install and will work the way its designed. Another more budget oriented way to irrigated row plants is flooding the trough between rows. You would need some slope (1.5%) down the row. This requires less watering time but causes more water to be used. If water is a scarce commodity, drip is 90% efficient and your pvc pipe or flood irrigation is 30-50% efficient. Just some things to think about really. I have used all these systems and more. Your system is very good and drawn very well but it would, like any farming system, need fine tuning after it is installed. In my humble opinion, there are no systems that work for all cases and therefore the least expensive. What would be nice is, after implementing your plan, discuss with the forum the trials and tribulations you experienced. I can help with the details if you want or how to do a water audit to fine tune the system. You will make a fine system with your plan. Go for it. JMHO Aloha

lehua,

Thanks for your reply - much appreciated. I suppose I should have checked more into the forum archives prior to posting - would have prompted me to first check into my hydraulic specs.

Our water does come from a municipal source, which obtains it's supply from local fresh water natural lakes/ponds and reservoirs. It is treated with chlorine and fluoride (1.0 mg/l) and has a moderate hardness of 68 to 84 mg/l. I just did a test by filling a 5 gal bucket from the freeze-proof garden bibb, timed it with my phones' stopwatch - and it took exactly 60 seconds to fill to the brim, which equates to 300 gal/hr.

The main vegetable planting area consists of (6) 36"+ wide x 18 ft long beds, each naturally bermed about 6" above the 18" wide pathways - which are freshly covered in straw mulch each season. Each row slopes along its length, approx 6" in 18 ft., or 2.8%. We also have a couple of 42" x 12 ft wood-plank raised beds for strawberries, herbs and smaller rotating crops. An 8' x 5' onion patch, 10' x 4' raspberry patch and a 40' x 3' mixed use bed along the east garden fence - all with about a 1.5% slope.

The soil composition is 12" to 18" of very rich humus, with a mix of loam + grey clay in the subsoil layers. I have been layering at least 3" of my own organic compost over each bed twice/season, which I first break down with my shredder/chipper. Water plumes have always spread very well when hose/pail watering in the past.

Organic additives, such as bone meal, wood ash, and dried blood are added regularly, with limestone tilled in the Fall, if soil ph tests require it. Concentrated fish emulsion is mixed with water and applied by hand to each plant during the growing season. Due to some early blight occurring on our tomatoe and pepper plants, which was spread I believe from water ground splash, I'm thinking drip irrigation may minimize this from happening.

I have not yet purchased the inline filter, 3/4" mains and 1/2" laterals, but have received the 3/4" ball valves and electronic water timer/valve I had ordered.

The author of a Utah Co-op Extension article on the prototype PVC system (see link), recommends drilling 1/16" holes, in 2-3 hole clusters, spaced to align with individual plants. My plan was to dedicate each lateral to plants with similar needs, with all lateral and major pipe joints being separable to accommodate seasonal rotation and off-season storage.

Since I have no experience with this yet, I was waiting for the time when my indoor grown seedlings are about ready for transplanting, before determining hole spacing. Drilling should be easy enough to do when that time comes by setting up a jig.

Sorry for being long-winded - many thanks for your encouragement, and system endorsement . . . I feel less like a pioneer now.

Best, Steve

Here is a link that might be useful: PDF - Designing a Baasic PVC Home Garden Drip Irrigation System

AD,

Good information but you didn't mention the pressure of your source. Not really necessary if you use your pvc system. Municipal systems are usually around 60-80 psi which more the better in your case. It would be good to check with a pressure gauge with a garden hose screw-on connection in case you have very high pressure in your area(80-100 psi). Then a pressure regulator is recommended for house or garden. Valves usually can handle 70 or less psi before they water hammer shut. You have good slope to collect energy loss as the water moves down the pipe. Let me know if you want to know how to perform a water audit. Very similar to the bucket collection method. 1/16" hole drilled is a good start but the size may be increased if there is enough pressure to decrease the watering time. What type of soil is also important in moving the water in the soil. Sounds like you are aware of most of these things and its not a concern. Actually, I am glad that a people are taking this system seriously. An interesting fact is that a World Record holder(Charles H. Wilber) for tomatoes used a similar system. Read his story. Its great. GL Aloha

Thank you lehua.

I didn't post any water pressure specs, since I do not have a pressure gauge - and since we live closer to sea level than many in our community, are fortunate to have good water pressure. As you alluded, I didn't think high pressure was an issue with my proposed manual PVC ball valves - also thinking that with manually controlled ball valves, higher pressure is desired. The electronic timer I bought, has a nylon ball valve - not a potentially problematic diaphragm valve.

My initial reaction to the 1/16" hole recommendation, used in the Utah systems, was that the holes were too small. Seems with larger holes, such as perhaps 1/8" - 3/16", the water may be turned on for shorter durations to reach optimum soil/root saturation - although I don’t know how this impacts plants at lower elevations. It would certainly be comforting to hear from anyone else who may have successfully experimented with this.

However, even though it may mean re-drilling all holes a bit larger - or at least the ones at the high end of each bed, I suppose it's safer. Once a hole is drilled, it cannot be made any smaller.

Thanks again - will re-post with pictures for anyone who may be interested, once the system in place - and if I'm lucky, functioning as planned.

Best, Steve

AD,

Good. All holes do not need to be drilled with the same size hole along a pipe. That is were your water audit comes into play every time you make an adjustment. Trial and error is a big part of this system and changes should be gradual. Aloha

I use this little system and it solves many problems for me. Here is the link: http://youtu.be/MNoL13ptJ6Y

Here is a link that might be useful: Simple easy DIY Drip irrigation