Are you connecting before or after the PRV (pressure redcing valve)? This will make all the difference in the world. You should be connecting before it to obtain maximum pressure. Its not that the 1/2" is to small (most systems are ran in 1/2" line) its the pressure that is not getting the heads to pop up.

marsha, I can't think of another way to do this when involving filters since your drip is sourced with you sprinkler system off the well. You are already deciding one filter for all the drip zones or separate small filters for each drip lines. Your well really dictates you not doing drip but small bubblers that sand can't clog or even a pvc pipe with 1/16" holes drilled in it and then drilled larger by the trial and error methods (There are some threads discussing this) or even small flood irrigation if you have the slope in the bed. JMHO Aloha

Thank you for the replies. 1) Starting pressure: Since the well is not dug yet, it's going to be prejections. But assuming I will get a free-flowing well like my neighbors (contrators say the same), I am going to have an aboveground spinkler pump, 1 1/2hp. Immersible turbine pumps can get esaily damaged by lightning in my area, according to my neighbor. It is limited by 45 psi shut-off pressure. So, 40 psi discharge pressure is reasonable. 2) I am not using a jet pump. According to the expert at the store I called, irrigation needs irrigation pump, not jet pump. Jet Pump can give pressure but cannot keep up with flow rate. 3) I am not usign a pressure switch or a tank. Again, according to the expert, irrigation needs a well and a pump. Don't use anything else, according to him. 4) Someone mentioned delta pressure of 2 psi at the sprinkler head. That is much assuring. 5) I am oversizing everything to minimize pressure drop. 2" lateral is an example. I really don't need this size. 6) Still, the valve pressure drop bothers me. I can see that there needs to be certain pressure drop across valve for proper operation (more for opening than closing?) But 4 or 5 psi? I am not convinced. I am going to use 1 1/2' valve. 7) In the worst case, I will go with microirrigation. (I am not watering lawn. I am watering plants, some in pots some in ground). That will cut down everything, pressure need and volume need. But I have to run black poly and 1/8 feed lines and micro irrigation heads. Thank you for sharing your experiences. I would not have know about water stream blown by wind at 40 psi, for example.

Winterization of your sprinkler system is not an area that I would suggest skimping on, particularly up here where it gets cold. If you search around you will find that the recommended compressor stats (for simple residential sprinkler system blowouts) are 10-25CFM at 60-80 PSI, a little further research and you will find that a compressor of this type is LARGE and EXPENSIVE, $1000.00+. Vastly more than you would ever need for blowing up pool toys and bike tires. The volume of air is the crux for consumer grade compressors they just do not move *enough* air to clear the lines completely, the air will override the water leaving the pipe partially full of water, which accumulates in the low areas, and freezes... I know a few folks who use their home compressors and have had no problems, I have also reinstalled systems where the freeze damage was so extensive replacement was the only cost effective approach. BELIEVE me I am a do-it-yourself homeowner, in fact I just this weekend completed replacement of 50' of my house foundation which was do it yourself to the extreme. It is my opinion that winterization by a proffesional is well worth the money. Good luck