Question
I live in Phoenix and need to re-install an irrigation system in an established yard of dessert landscape. Two designs have been submitted. First, a two-zone system, front and back, that will use schedule 40 PVC, with manifolds spaced along the trunk line.  The manifolds will distribute water to nearby plants via spaghetti tubing.  Second contractor's design is to hard-pipe schedule 40 PVC to each plant and install self-cleaning drip heads on the top of each PVC riser.  Two zones, one for cacti / succulents and one for all other plants (first design addresses this with low flow heads for succulents on same zone as other plants).  Second quote is $900 more expensive (due likely to more trenching labor).  Am I really getting a much better system, or more reliable system, for the extra $900?  The extra money is not a big deal for me, but I do want to get good value for it.  I believe both contractors will use quality parts and both have excellent reputations.

Answer
Hey Mike, I would tend to prefer the second option, in that the cactus/succulents probably only need to be watered every couple weeks in the summer, and maybe not at all in the winter, whereas the other shrubs would need it more often, maybe every 5 days in the summer and every 2 weeks in the winter. With the second option, you would be able to water more efficiently and save some water at the same time. Also with the second option, you are eliminating the spaghetti tubing. It might be better to request that the risers be made with flexible 1/2" PVC and 2 male adaptors instead of the rigid schedule 80 PVC nipples that it sounds like they would use. If the plant/roots grow into the PVC nipple it might have a tendency to crack the pipe down below, the 1/2" flexible PVC and 2 male adaptors will have a tendency to flex better. You might have your first contractor bid the system using the spaghetti tubing, but have him do 2 valves separating the cactus/succulents from the shrubs, instead of 1 valve front and 1 valve back, this will give you a closer bid apples to apples. I would imagine the new bid would come in within $500, and definitely do the second bid with the hardline. Also make sure that they are using "Bowsmith" emitters, they are the best on the market. Good luck and have a great day.