[GpsFrontier]

Hello Davephan,
Yes your house shroud have a water pressure regulator, and it's required by city code. It protects your household pluming from rupturing and causing water damage to your home. It will be outside the house and above ground. It will be installed just below the water spigot closest to the water meter where the water line from the city to the house comes from. I attached a picture of one by itself, as well as one that's installed to show you what yo look for. They generally run about $80, and are easy to install (if your handy).

Yes it's never a bad idea to have backup protection for your RO system, and $15 isn't a bad price for that backup protection. But if your homes water pressure regulator isn't functioning properly, you run the risk of tens of thousands of dollars in water damage to your home, and the RO system would be the least of your worries.