I used water filter units that have a neat valve on top that allows you to turn off the water at the unit, change the filter, and then turn the water back on easily. I like the clear plastic units because you can see when its time to replace the sediment filter. You can also tell when the filtler is needs changing when the water pressure in your shower drops significantly. The bare copper wire you see behind the filter units continues the ground connection of the water system. Many homes have a ground from the fusebox connected to the water main, which runs out into the yard, functioning as a ground. Because we used plastic units, the ground connection was broken, so we clamped in 10 gauge copper wire to make it all right.