Henleaze Plumbing

The pressure in the mainline is less than at the branch because of friction losses. The main pipe has to carry water from your home's service meter all the way to the street for every single faucet and fixture. All those fittings and bends reduce the flow rate. The pressure in smaller branches that branch out from the mainline is also less than the main pipe's pressure because of friction losses. In fact, there are further reductions in pressure at each turn due to friction loss, e.g., for a 90-degree elbow, the straight pipe has no friction loss, but the one fitting has 90% of the pressure loss to maintain an equal flow rate. It is a mechanical thing due to physics law. The pressure in your home plumbing depends on the number of branches. In addition to friction losses due to pipe fittings, non-uniformity of pressure is caused in pressurized water lines by 'compression' (where one line is shorter than another) and 'expansion' (where one line is longer than another). The most basic cause is that a pipe with restrictions (a closed valve, a faucet/equipment in use) will have less water and lower pressure than an unobstructed pipe. But there are other causes of unequal pressures. Smaller pipes have more trouble distributing the same amount of flow to all portions of the house - particularly when those must cross a distance and be combined into one pipe. The water company will charge more for water in high-pressure zones. They may claim that their pipes are better, but the main reason is higher sales volume in high-pressure areas, which allows them to recover maintenance costs faster due to less frequent breaks. There are also many reasons for pressure drops in water mains these include friction (pipe diameter, pipe material, length of the pipe).