I had a well and was running into a lot of calcium build up, so I connected to City Water. The cold water will not run in both my showers, but runs every where else in the house. What can I do to fix this problem?

Do you get hot water out of these showers? Are your water lines in a concrete slab, under the house in a crawl space or in the attic? Are the two bathrooms close together, perhaps the showers sharing the same wall?

From what you have told us so far the likely issue is a build up of calcium or other junk in the cold inlet of the mixing valves. If you tell us what valve you have or post a picture we may be able to help you clean out the valve