How does water pressure work?

Ever wonder how the water pressure in your home works? Although many people understand where their water comes from, most are unclear on what happens between the city water supply and the kitchen sink.

Why is it important to know about water pressure? Because the next time you have a low-water pressure problem at home, a basic understanding could help you find a solution.

When it comes to water pressure, the story is pretty simple: the water pressure behind your faucet, for the most part, depends on gravity. As such, have you ever noticed that:

• Municipal water towers tend to be located on hilltops.
• A typical water tower is a very tall structure.
• Reservoirs are usually found in geographically elevated areas.

The reason?
This allows the water to flow naturally downward, either to your home’s water pipes or a local water treatment plant.

Of course, reservoir and river water must be purified before it can be used in homes.

• Before you receive it, it gets directed downhill to the water treatment plant and then into the water tower or the city water mains, which then feed your home’s water supply.

Water towers measure around 164 feet (50 metres) high, on average.

• As a rule of thumb, the higher the tank, the greater the water pressure. In fact, for every 2 1/3 feet (0.7 metres) of height, you’ll get one pound of pressure in a one-inch diameter pipe.
• Water pressure is measured in pounds per square inch, or PSI.

You're probably wondering how clean water gets from the municipal water treatment plant into that tall tower. That’s where electric water pumps come in.

• These variable-speed pumps send as much water up into the tower as is being used, so that during periods of high usage (morning showers, anyone?), the pumps operate faster and pump more water.
• When the tower is full, the pumps slow down. When the level drops to a particular point, the pumps are activated to start filling it again.

Storing water in water towers keeps the pumps from having to run all the time, which means using less electricity, resulting in a lower monthly water bill for you.

The water in your nearest water tower is already treated and goes directly to your home, often at a greater pressure than your water meter and pipes can accommodate.

• To ensure that the water pressure caused by gravity doesn’t cause the water pipes in your home to explode, you probably have installed near your water meter a water-pressure regulator. Good thing, right?

Water from a well is a different matter.

• If you’re not on a municipal water line, then your water may come from a private well, which requires a pump to bring it up and into a pressure storage tank on your property. Long gone are the days of a bucket on a rope!
• The water storage tanks, which come in various sizes, are often located in the basement of a house.
• The power of the pump needed to distribute the water throughout the home depends on the number of levels in the house. Do you have a second storey? Then you’ll need a more powerful pump.

A rubber bladder filled with air can be found inside these pumps. This simple mechanism can keep track of the pressure in the tank and control the operation of the water pump.

• When the water pressure in the tank increases to a particular point, the pump will turn off automatically. When water is drawn out of the tank, the pressure will drop, and the pump begins operating again.

You should now have a better understanding of how water pressure works and how the path water takes to get to your home affects the pressure. The next time you take that nice morning shower, you’ll have a better appreciation of how it all works!