The 3-way ball valve is designed to allow 3 different ports of water to be attached to it at any one time. The switch on the valve controls how the water flows through the pipe. There are two different types of valve, the "T" valve, which allows water to flow to a single point, and the "L" valve which is designed to carry water through a particular angle. The "T" valve can connect all of the ports to each other, but the "L" valve can only connect one of the side ports to the central port at a time, and never both of the side valves together. This kind of ball valve is designed to be easily fixed and repaired, so if you locate any kind of problem with the three-way ball valve, you can easily troubleshoot it and then make a repair.
Ball Valve is Blocked
This is a common occurrence due to the number of ports through which water can flow. This water travels through the valve, and can deposit debris at any point, making it more difficult for water behind to flow through accurately, and also encouraging the build-up of more dirt. However, the 3-way ball valve has been designed with the understanding that this problem might occur. In order to remove the debris, you can easily remove it from the pipes, clean out the sediment in a sink, and then replace the valve back in position.
Ball Valve is Jammed
Another common problem which comes with age is that the switch on the valve which allows you to control the movement of water becomes fixed in one place. This is usually due to lack of regular use, although it is also possible that corrosion can effect the 3-way ball valve, and be passed over to the switch. In order to fix this problem, you will first need to clean the switch thoroughly, and then check it for signs of corrosion. If there is any rust or damage, then you should treat it with the relevant chemicals, but if there is no damage, then a good application of lubricant such as oil should fix the problem.
Ball Valve is Leaking
A final problem is that the 3-way ball valve is leaking. This is most likely to be due to a break in the seals which surround the valve. You can remove these individually and replace them, solving the problem. In addition, you may find that the ball valve has developed small cracks or flaws on the surface, usually near to where pipes are connected. This can be caused by corrosion, or simply due to age, and indicates that the 3-way ball valve needs to be replaced with a suitable alternative. As a quick fix while waiting for the replacement, put plumbers tape around the edges of the pipes, as this will provide a temporary seal between the valve and the pipework.