Tired of refilling that slow plastic water pitcher three times a day, I bought one of those heavy-duty, three stage reverse osmosis water filters that mounts directly under the kitchen counter. The manual made it look like a breeze just splice into the cold water line, mount the small storage tank, and hook up the separate little faucet through the sink hole. Instead, I spent my entire evening crammed into a dark cabinet fighting with stiff plastic tubing and leaky compression fittings.
The absolute worst part was the lack of space under the counter. With the garbage disposal and the main drain lines already taking up 90% of the room, trying to slide the heavy filtration brackets onto the side panel was a total geometric puzzle. Every time I reached back to tighten a mounting screw, my elbow would smash directly into the metal drain pipe. I had to lay flat on my back with a flashlight balanced on my chest, getting a face full of old cabinet dust every time I moved.
Connecting the tiny plastic water lines into the existing copper plumbing valves caused the real panic. The quick connect fittings are supposed to just slide together and seal automatically, but the ancient brass valve under my sink was slightly corroded, so water kept spraying out in a steady mist the second the main valve opened. I had to shut the whole house water line down again, unscrew the supply line, and spend thirty minutes wrapping everything in heavy Teflon tape until it finally stopped dripping.
The filter is finally mounted now and the separate little chrome tap on the sink is running perfectly clear water without any leaks. It takes a full minute just to fill up a standard glass because the pressure from the small storage tank is incredibly slow, but the water tastes fine. Now I just have to wait for the kitchen tiles to dry out from the initial leak before I can put all the dish soap bottles back under the cabinet.