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Water Pressure
(Not the same as water Flow or Volume)

Water pressure:
the force (flow strength) of water pushing on a unit area, usually measured in pounds per square inch (psi).

Static water pressure:
water pressure, measured in psi, at the service line when there isn’t any water running.

Residual water pressure:
water pressure at the service line when water is flowing.

For most of us, our water comes from a municipal water system, where it’s usually extracted from various groundwater sources and treated to remove impurities. It is then pumped to large water towers that rise above than the highest delivery point in the system. Gravity provides the pressure that forces the water through the water mains (pipes) and eventually into our homes.

Water towers store water for future demand, which peaks predictably during certain times of the day. When water is not at peak demand, water is stored in the tower, and the water is distributed by pumps.

If the pump is producing more water than the water system needs, the excess flows automatically into the tank. If the community is demanding more water than the pump can supply, then water flows out of the tank to meet the need.

Water pressure depends on water flow. The more water being pushed through a pipe, the more pressure there will be naturally.

The less water there is in a pipe the less water pressure. The more you decrease the volume of water the greater effect it has on lessening water pressure.

Pressure is a one-way street. It can always be reduced, but it cannot be increased unless there is sufficient volume to sustain it, and the volume is strictly a factor of pipe capacity.

The pressure of the water delivered to your home will vary depending on your elevation relative to the source, as well as the complexity and condition of the piping system that delivers it. But once established, the pressure will be constant, and will not change based on demand.

Typical residential systems are designed to function under a pressure of 40-70 psi.

If the water pressure entering your home exceeds this level, you may need to install a pressure regulator in the line to reduce the pressure to an acceptable range. This protects the equipment in your home from damage caused by excess force exerted by the water.

If your home is at a higher elevation, your water pressure may be below average. If it is below 40 pounds per square inch a pump may be required to boost water pressures in the house.

Do not confuse water pressure with water flow.
Water flow is the result of pressure on volume. Volume is the amount of water available for delivery, and pressure is the force exerted on it. There is a big difference between the two.

Water can lose 2 lbs. of pressure for every 10 feet of run (about 8 psi), as it rises from the basement to the second floor.

Friction on the interior of the pipe lines, the distance that water travels to its sources, and the size of the pipes used, are also important factors in determining proper water pressure.

Improving water pressure is often a complicated problem that can only be handled by a professional, if even then.

However, if the problem only appears a single sink faucet or shower head, it can be replaced with one specifically designed to increase water pressure through the head, may help. It won’t increase water pressure to the home, but it will simulate higher water pressure at the fixture.

 
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