Any water shut off valve can leak at any time. Do not be surprised if you have a new water shut off valve leaking. There are many issues that can cause or facilitate a leak. You must delve into the details, find the actual cause and address it to resolve the problem.
Perform an Inspection
Let us first address the simplest of all possible causes of any water shut off valve leaking. It is possible that the packing nut has loosened a little. Poor installation can leave behind a loose packing nut. All you would need to do is get a wrench and tighten the packing nut. Usually, a just a small twist will do and you wouldn’t have any more dripping and water leaking. If slight twists don’t work, then tighten the packing nut enough till you cannot turn your wrench anymore. However, be careful not to damage the threads inside. If you damage the thread, then the packing nut may not get tightened appropriately. You don’t need brute force to tighten the small nut.
Make Sure All Packing Washers and Nuts are Secured
At times it is not the packing nut but the washer inside. It is known as the packing washer. Should there be any leak in the packing washer, you would have a leak even if the packing nut is reasonably tightened. A completely sealed packing nut will prevent the leak but the washer will let some water through which will keep the pressure up and the nut will loosen in some time. You should get the packing washer replaced.
Make Necessary Replacement of Parts
In some cases, both the packing nut and the packing washer must be replaced. This is common in very old valves systems. Worn out or damaged valve systems will require a complete replacement. You might want to check the valve handle, the stem and the condition of the interiors of the valve to look for signs of corrosion. Heavily corroded valves, worn out washers and loose packing nuts call for a complete replacement.
Fluctuation in Leak
There are times when the valve would be fine but excessive water pressure will cause a leak. You can tighten the valve or the packing nut in such cases. The water pressure does fluctuate through the day and night depending on how much water there is in the overhead tank and hence how much water is flowing through the plumbing system and through the valve. You may want to check the water pressure if you have a regulator connected to the mains.