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It sounds to me like you go from your main water supply to a valve. Then run the PVC from that around where the sprinkler heads go.

It might be more complicated than that. I had my sprinkler professionally installed, and they put a complicated one-way valve gizmo above ground between the water main supply and the (below-ground) valves that drive my two zone sprinkler system. City regulations require me to have the thing inspected annually. I think the concern is that assorted yard crud might make its way back into the water supply, no doubt polluting our precious bodily fluids.

Your local regulations may vary.