Geography

• According to the San Jose Water website, houses located at a higher elevation than the water tank or reservoir will experience decreased water pressure compared to houses at the same or lower elevation. A low amount of water in the reservoir, such as during a drought, might also cause a temporary lowering of water pressure until the water level reaches normal levels.
  
  

Leaks

• Problems with the water lines maintained by the public water utility can lead to decreased water pressure, explains the San Jose Water website. A leak in a water main can cause homes to experience low water pressure, and this problem is usually the utility's responsibility to repair. A leaking service line between the water meter and the customer's house can also cause water pressure to drop. Homeowners who notice higher than usual water bills might investigate whether their water line has a leak or whether equipment such as a toilet or sprinkler system is leaking, causing the household water pressure to decrease. To check for a possible leak in the home, monitor the water meter reading by looking at, waiting one hour without running any water, then checking the water meter again. If the readings do not match, there might be a leak.
  
  

Equipment Malfunctions

• Homeowners who utilize a water softener might experience decreased water pressure if the water softener malfunctions. If the water meter valve or the house valve is not fully opened or completely closed, the house will have little to no water pressure. Additionally, a malfunction of the water pressure regulator installed in some homes can cause intermittent or constant decreases in water pressure.
  
  

Wear and Tear

• As pipes and faucets age, normal wear and tear can lead to decreased water pressure. Low water pressure in a single faucet or shower head might result from clogs or rust in the aerator. Cleaning or replacing the aerator should restore normal water pressure to the faucet. Years of mineral build up resulting from hard water can reduce the volume of water able to flow through the home's pipes. According to the Las Vegas Water District, a worn out water heater might result in decreased water pressure when running hot water.