Water pressure is measured in pounds per square inch (psi). The water pressure output of a shower is influenced by several factors including the type of shower head. Many manufacturers of shower heads advertise high-flow, high-pressure products, while others stress the decreased environmental impact of low-flow shower heads. Though aesthetic factors are also a consideration in choosing a shower head, many people use water pressure to choose the right shower head for them.
Most people consider low water pressure to be a negative feature of a shower head. Low water pressure can lead to longer showers and difficulty completing shower tasks like rinsing. High water pressure is considered a desirable feature of a home or shower, but high water pressure can also lead to pipe erosion and plumbing damage. Many shower heads also include a regulator inside the device which helps control the flow of water for homes with high water pressure.
Water pressure guidelines are regulated by the federal government. Prior to 1992, shower heads could produce as a much as 5.5 gallons per minute (gpm). However, new regulations require shower heads to have a flow rate that is below 2.5 gpm. The water pressure of a shower head cannot exceed 36.3kg. per square inch (psi). Shower heads include flow restrictors which regulate the amount of water that is allowed to pass through the shower head.
Water pressure is affected by both the flow rate and pounds of pressure per square inch. Though shower heads are one factor in determining water pressure, elevation and gravity are also major factors. Towns use reservoirs to provide water service to homes. Most towns place reservoirs at higher elevations than homes so that gravity will provide most of the energy necessary to get water into homes. However, some flat areas or areas that are far from the reservoir will require pumping systems to receive water. Gravity flow tends to provide more consistent high water pressure than pumping systems.
There are two main types of shower heads on the market. Aerating shower heads create a mist instead of a direct stream of water by mixing the water with air. Aerating shower heads create more steam and radiant heat than traditional laminar-flow shower heads. Laminar-flow shower heads do not add air to the water, and so the flow of water is a stream instead of a mist. Laminar-flow shower heads are popular in warm climates where the permeating steam of an aerating head would be too hot.
Though regulations limit the amount of water and the amount of water pressure of shower heads, many homes are opting for low-flow shower heads that come with the most restrictive regulators. Low-flow shower heads can save between 20 and 60 per cent of water, which not only benefits the environment but also saves money. High water pressure can also age appliances and pipes more quickly than lower water pressure.