Age-old technology, modern results

Have you ever noticed that when there’s an electrical failure, you usually still have water? That’s because our power source is one that has, quite literally, stood the test of time. Although there have been some improvements over the years, it works on the same principle used by ancient cultures such as the Romans, Egyptians, and Persians, and it even has a stamp of approval from Sir Issac Newton himself.

A catch basin for an ancient aqueduct in Metz, France. In Rome, the combined aqueducts could supply about 300 million gallons of water a day! Photo courtesy François Bernardin/Wikipedia

We’re talking, of course, about gravity.

The way LCA’s infrastructure network functions is similar to a bathtub. Our goal is to keep the water level in the tub at the same level all the time in order to create consistent system pressure. Our wells pump groundwater directly into the “bathtub” via a network of pipes, and the water level rises. At the same time, customers are using water and drawing water directly out of the tub’s “drain,” and the water level drops. This prompts the wells to pump more water to maintain the level the network needs.

In this case, LCA’s bathtubs are big, round tanks that are strategically placed on hills to maximize the power of nature. You may have noticed them in and around the communities we serve. The amount of water they can hold ranges from 250,000 gallons up to 5 million gallons.

For our primary water system in central Lehigh County, we have 9 million gallons of water storage available in our reservoirs. During an average day, the demand on our system (about 19,000 homes and businesses) is about 6 million gallons per day. Which means that in theory, we have about a day and a half of water available in our tanks if the power fails.

However, during extended power outages, some customers will run out of water long before the tanks are empty because the water in these elevated tanks helps to achieve consistent water pressure to our water customers. When the water level drops, so does the pressure. As an example, consider a garden hose that is filled with water. When the faucet is turned off, you will still have some remaining water come out of the hose, unless you lift the end of the hose up high, in which case the water stays inside the hose. During a power outage, the same thing happens to a person who lives at a higher elevation. Even if there’s water in the pipe leading up the hill to a house, the residents may not be able to run their water if there’s not enough pressure to drive the water all the way up the hill.

When everything is running normally, LCA’s reservoirs provide this pressure because they are all positioned at the same elevation (580 feet above sea level, to be exact). That’s higher than the elevation of the rest of our service area, and gravity creates pressure because of that difference in elevation, keeping the water pressure in the system consistent for all customers. Although people at lower elevations may have somewhat higher water pressure than their neighbors who live on a hill, in general the pressure inside should always be about the same.

However, if the power goes out for a long time and LCA has to rely only on storage, the water pressure in the system drops as water level in the tanks drop, to the point where people at higher elevations start to lose water before the tanks are empty.

If you notice changes in water pressure and we’re not experiencing a power outage, it may indicate a major draw on the system —such as a fire hydrant being opened to fight a fire, or a major water main break. Call LCA immediately if you notice a sudden, major change in water pressure!