ptg, Some additional info needed. The controller is located where? How many zones are hooked up in the controller? Where is the mainline shut-off in relation to the controller? You had a sprinkler contractor out to look at the system and all he could come up with is get a metal detector? If you can't find the valve how do you turn off the zone? Do you know where all the other auto valves are? Pictures would be helpful. Is the water source from the house(hose bib)or from the mainline to the house? These questions are a start. The forum is at a disadvantage because we can't see the your lot nor walk around it. The more info the more we can help. You may have to do some probing or listening. Aloha

I doubt the line going to your water heater is actually plastic. More likely it's plastic covered stainless steel. If you are doing quite a bit of modification to your existing piping it may be more cost effective to replace it and use the new corrugated stainless steel tubing (CSST). It is more expensive per foot, but the labor is much less to install. I think CSST has higher pressure drop so you will probably need a larger diameter tubing. I would check into this as well as the plastic tubing, which I've seen used outside to supply a standby generator on Ask This Old House. Good luck, Tom

The black pipe is almost certainly polyethylene-- an excellent choice for that purpose, in my opinion. An adapter of the style below is best. I suggest avoiding galvanized steel adapters as they will rust and will be consumed by electrolysis if directly connected to copper or brass-- but they are stronger than any non-metallic adapters. I use two clamps at each adapter. Be sure you have the correct style and size for your pipe. The adapter should be difficult to insert and to remove-- tight fit. If not, it is the wrong one. Do not select from the irrigation fittings bin unless there is no other choice. Here is a link that might be useful: Male barb adapter

The "Supply Pipe" is the direct burial pipe from the municipal water main or well to the structure. While copper certainly is well suited for this application copper has three drawbacks. 1.Cost 2. Hard drawn copper pipe is in 20ft lengths and annealed copper pipe is made in 60' rolls which means we would normally have to make one or more joints underground. 3 Under some adverse soil conditions copper pipe will corrode from the acids or alkali in the soil. For these reasons I prefer to use continuous roll Polyethylene pipe which is commonly available in rolls up to 250' long, and in some instances 500' by special order. In this manner we can install a joint free pipe that has a proven track record of providing 50+ years of service. "DISTRIBUTION PIPING" is the pipes within the structure that distribute the water from the house main to the point of demand. The alternatives here are Galvanized Iron pipe, Copper pipe, PEX tubing, CPVC Pipe(difficult to find and almost never used), CPVC-CTS tubing, and if your under the IRC you may use Polybutylene although with the number of failures and class action lawsuits against PB I don't understand why anyone would consider it. I have heard all the arguments in favor of PEX but in my region copper has shown to have a proven reliability of 75+ years (and most of that old copper is thinwall type M with lead solder joints.) It hard to beat a success. "DWV" piping is the Drain, Waste and Vent (Sanitary Waste) pipes in your house. While they do make DWV grade copper pipe most homeowners would find it labor intensive and cost prohibitive for residential construction. The alternative here would be No-Hub cast iron pipe, PVC or ABS. Here again, most homeowners find No-hub cast iron to be cost prohibitive. The choice between PVC or ABS is generally a matter of choice or local code requirements but in the end, both have proven to be an economical and extremely reliable type of pipe for this application.