I would greatly appreciate any advice, ideas, or insight. I'm sorry for the length of this but I tried to include as much detail as possible.

I have been having a problem with my water pressure over the last 6 months or so, with it going low during showers and other higher usage times more often and to a greater extent than in the past. Now my irrigation system seems to be effected and I have new seed out on the yard after new landscaping.

I had some landscaping done around my backyard pool two weeks ago which included installation of a new irrigation system in the backyard only. However, I noticed that not only does the shower pressure virtually disappear at some point or points in the irrigation cycles (which are more frequent than usual because of the need to water after hydroseeding more frequently).

I noticed earlythe other morning that one of the zones (zone 15 of 18 total) would peter out in the middle of the stations set watering time- the heads would just drop into the ground and continue to bleed water with time still counting down on the control panel in my basement. Zone 1 &2 are off (established mulch beds), 3 to 5 cover the front yard, and 6 to 18 cover the backyard. Zones 6 to 18 is the new backyard system (the prior one being destroyed by digging the pool) installed by my irrigation contractor two weeks ago. Zones 6-16 are rotary or spray head zones, while 17 & 18 are both drip irrigation zones for the new planting beds around the new pool. The way it is programmed now, front yard zones 3, 4, &5 (rotary heads, 30 minutes each zone) irrigate first, followed by 6-16 (rotary and spray heads, about 12 to 15 minutes each), followed by 17 &18 (drip irrigation, one hour each). There is a 10 minute station delay between each station (which I increased a few days ago from the 5 minutes the contractor programmed).

I tried to do some diagnostic maneuvers of my own thinking this morning:

First, I ran zone 15 earlier in the cycle, moving it up manually to follow zone 12, in case the well was running low/dry. It worked fine. However, all subsequent zones 6-16 also went through their stations without a problem. Even after all 16 zones had watered, I was able to have zone 15 water again without any difficulty. I will say that I notice on most zones that the water pressure drops a bit after the water seems to run out of the tank below the tanks pressure switch "cut-on" point (40 psi) when the well pump is activated, but it is not severe and watering seemed satisfactory. Then I remembered, because it was a weekend- today, Saturday, no one had taken showers that early in the morning (6:30am). Usually, by this time on a weekday, four showers would have been taken, potentially dropping the well's water level significantly.

Up to this point, I was at least pleased that everything seemed to be working ok. However, when I manually turned on zone 17 (drip irrigation) after finishing watering and testing maneuvers for 6-16, the well tank pressure gauge dropped somewhat quickly to the 40 psi cut-on point, the well-pump was triggered and audibly began pumping as usual. But about 20-30 seconds after the pump started, the pressure would drop suddenly and precipitously from about 38 psi to 16 psi (within 3-4 seconds). Well pump could be heard to continue pumping. Over the next 10 to 15 minutes it slowly decreased to 12 psi when I turned zone 17 off. Before shutting it off I repeated this several times and each time it had the same sudden drop in pressure at the same point. I then turned on zone 18, also drip irrigation, and it did the same thing as 17- sudden severe pressure drop, pump still running. I wondered if this zone might have a leak. My irrigation contractor looked at it this morning and couldn't find one. He thinks the pump is going bad.

The pump is a 2-wire, 1 hp pump, installed in 1993 when the home was built, as far as I know. I bought the home 10 years ago and doubt although do not know for sure that the pump was ever replaced. So I am presuming the pump is 20 yrs old. Per dep of health well test records: the well is 220 ft deep, static water level 40 ft, pump positioned 180 feet down from grade. With 1 hp pump, show 10gpm down to 7gpm over 24 hours with static water level depth after 24 hrs at 160 ft., overall well yield 8 gpm.

I should add that I had a well contractor out a couple of days ago to take a look. He doubted it was the well pump going bad. He said they either work or don't work- 'mine is working so it should be ok,' he said. He said rarely is it a problem with the well itself. He did charge/pressurize the tank which he said was quite low at 18 psi to, I think, 38 psi, and changed out the gauge and switch. He said it could be the metal pipe fitting leading into the tank that sometimes clogs as another possibility. He doubted it was the tank itself- it is Amtrol WellXTrol, 60 gallon tank, stamped 1992. He said it seemed to be in good condition at least from the way it looked on the outside. He said he did not detect a leak in the bladder.

I have no idea what is going on here. I'm more confused than when I started looking into it. Is the well running dry or depleting too rapidly? Is the pump "going bad" but not dead yet? (My irrigation contractor said that under stress the pump may go into a protect mode or overheat and go from 220 to 120volt?- not quite sure what he said), Do I need a new well tank, new t pipe or a new pump, or both? Do I need a new or deeper well? Is it not producing enough water anymore? Could there be an unseen leak in zones 17/18 ( I think they are tied in together with a common feeder)?

Any suggestions? I could really use some help here and it will be greatly appreciated. I'm hoping to avoid an expensive piecemeal replacement of the entire system which I feel might end up occuring without a true diagnosis of the problem.

Thank you.