Step 6 · Turn On Water and Check for Leaks
With the filter installed, it's time to test for leaks. Go back to the shutoff valve and turn it on very slowly, allowing the line and filter to fill with water gradually. Once the hissing sound stops, fully open the valve. Return to the filter and meticulously inspect both the 'IN' and 'OUT' connections for any signs of dripping. Use a dry towel or your fingers to feel around the fittings, as some leaks can be very slow. If you detect a leak, shut off the water immediately and tighten the leaking nut slightly (about 1/8 turn) before testing again.