Light Green PVC use

Hi all. Been a visitor here for a few years but never posted until now.

Where I work we have a building with a fire and domestic service. The fire pump failed the test on low flow last time and we are trying to figure out if maybe the line wasn't replaced and upsized from a 4" to a 6" like it was supposed to have been when they installed the new service so we dug it up today and found the service was pipe with light green PVC. This feeds both fire and domestic water. I always thought this type of pipe was for drains only and low pressure non-potable water. The pipe is 6", at least at this point it is. We are gonna dig up another spot a few hundred feet away to check there too.

Is this correct or no?

See pic. Thanks.

I don't know what it is, but I would expose some more hoping to find some markings on the pipe.

Look like the same service pipe my local water utility uses when replacing mains.

Without seeing the specs on the pipe it looks like high pressure pvc which is good for 4-8oo psi.

Green SDR pipe would NOT fit into those fittings because its o.d. is undersized. IT would also blow out under common water main pressures.

I guess we are safe then. Thanks to all for the replies. Relieves some worry.