Before fixing the water pressure, it is necessary to diagnose whether the problem is applicable only to the sink or to the whole plumbing system of your house. Let us discuss the different causes for this issue.
Fixtures Turned On at Same Time
This is the most obvious cause. When two plumbing fixtures, connected with the same plumbing system, are turned on at same time, the water pressure in both the fixtures is lowered. Suppose the shower and the sink tap are turned on at same time and both of them are connected to the same supply pipe. In this case, there will be a drop in the flow from both.
Galvanized pipes/ Cast iron pipes (Mineral Deposits)
The problem can also result from the use of cast iron pipes or galvanized pipes. Hard water contains a high percentage of dissolved minerals. Oxygen in the water reacts with the metal of the pipe and rough surfaces are formed. The minerals get deposited on these rough surfaces, resulting in blockage and thus, the pressure goes down. Contact a plumber and get the pipe replaced, if this is the cause.
Elevation is a gravitational condition caused due to the incompressible nature of water and its tendency to spread in a horizontal direction. Thus, water in pipes applies pressure in the horizontal direction even when the pipe is vertical. Hence, water pressure problems may also be caused when the tank is situated at a low level, thereby, making it difficult to pump the water to the faucets. Ensure the tank is situated at a height above the house. If this is not possible, another solution is to install a booster-pump by a plumber.
Any leakage in the pipe, small or large, will cause low pressure. So, check the pipe for any leakage. Sometimes it may happen that the leakage is not visible and the cause remains a mystery. At such times, in order to crosscheck if there is any leakage, turn off all the water sources in the house and note down the water meter reading. After two hours check the meter readings. If the readings have changed, then it means there is a leakage. Get the leakage fixed from a plumber.
Another reason is blockage of pipes. If the over-tank is not covered or closed properly, there are chances of unwanted things falling in the tank and causing blockage in the supply pipe. This will result in problems.
Design of Plumbing system
Another common cause can be the faulty plumbing system used. The pipes used may be too narrow and this may restrict the flow of water. Replace these pipes in such cases.
In case, you notice low water pressure in any of the faucets in your house, find whether it is due to any of the reasons given above. It is recommended that you consult a licensed plumber to fix the problems that are complicated.