My pressure reducing valve is leaking. It is located on the property side from the customer valve. It appears to have two unions of some sort on either side of the pressure reducing valve. A San Antonio Water Systems guy came out and looked at it. He told us we would need a 3/4 inch pressure reducing valve. My question....is this relatively easy to do? I'm not a plumber, and do some DIY stuff here and there, but nothing big. I'm asking about this because of the two unions on either side, and the fact that I can turn the water off to the house. And there is a decent amount of room to work with. I appreciate any advice! Here are some pics of the valve.

This is the left side of the valve (towards the house)



This is the right side of the valve (to city water, and you can see the yellow shut off valve)

I don't see the union nut in the picture of the house side of the valve, just male threads. It looks like there is a pvc pipe inserted inside the valve. The white collar looks like a glued pvc coupling. If the pvc pipe is threaded into the valve and there isn't an actual union, you will have to cut the pvc pipe to get the valve out. Make sure you know how it goes together before you tear it apart. The issue maybe whether you have the tools needed. Do you know what is actually leaking? If I was going to guess, my bet would be on the connection from the valve to the pvc pipe. It isn't a tough job if you have the right pipe wrenches or large adjustable wrenches. I do a lot of industrial piping work and it isn't very often you see those valve parts fail.

The leak is on the underside of the pressure reducing valve. It's a pretty good leak too.

I believe he has 2 different "boxes" sitting next to each other..

I also believe the nut is removed from the union in the first picture.. I see threads..

It aint that hard but you will have to remove the "boxes" to give adequate work space!!!

Why replace when I can sell you a rebuild you can fix from the topside.

yep...easy fix. Just cut water off, relieve pressure and remove everything between the unions. Take it to your favorite home supply store and get them to give you everything to make the exact set up. Take it home and install.