Most building codes require a minimum water pressure of at least 20 psi. Water pressure above 80 psi is too high, and can damage pipes, joints, seals, and fixtures. Low water pressure can waste water, and you'll spend more time trying to do tasks like showering or rinsing dishes.
All taps and showers are rated with a minimum required pressure rating, which will usually be between 0.1 and three bar. Anything below one bar is considered low pressure.
Most of those guys generally agreed that the 2.5gpm is fine for most people, but had varying methods for increasing that figure for folks who wanted more pressure/flow. One guy pretty much ended the thread with this system though:
Residential water pressure tends to range between 45 and 80 psi (pounds per square inch). Anything below 40 psi is considered low and anything below 30 psi is considered too low; the minimum pressure required by most codes is 20 psi. Pressures above 80 psi are too high.
40 to 60 psi (pounds per square inch): This range is generally considered optimal for household water pressure. Within this range, the water flow feels adequate and satisfying, providing a strong and consistent shower experience without causing discomfort or potential damage to plumbing systems.
Considering shower head flow rate typically is between 1.8 gpm to 2.5 gpm, if we use 2.2 gpm as a medium number, and consider the pressure drop (remember that all shower heads are rated at 80 psi, but house pressure typically are not at 80psi), then the shower usage would be somewhere between 16.5 gallons to 18 gallons ...
Normal water pressure range
In general, residential water pressure ranges between 45-80 psi (pounds per square inch). If your water pressure is under 40 psi, it's considered low. A psi between 20-30 is considered very low, and under the minimum water pressure required by most building codes.
Modern houses and flats usually have 25mm diameter water supply pipes which allow a greater flow of water which may be more suitable for modern appliances. We aim to provide at least 1.0 bar of pressure at the point of connection or stopcock (which is normally found at the boundary of your property).
Pressures above 80 psi are too high. Whereas low water pressure is more of a nuisance than a serious problem (some fixtures, like washing machines, have minimum pressure requirements), high water pressure carries with it a significantly increased risk of damage to pipes, joints, fixtures and seals.
Plain and simple, less shower head diameter means higher pressure.
Standard shower heads use 2.5 gpm, but to earn the WaterSense label, a product must use no more than 2 gpm and still meet strict performance requirements. The EPA estimates that the average family could save 2,900 gallons of water per year by installing a WaterSense-labeled shower head.
The bar rating – 1 bar is ideal for smaller shower heads, 2 is best for multiple showers, taps or appliances, and 3 bar pumps are best for power showers and large shower heads.
1.5 GPM. This is considered a low-flow option and is designed to conserve water. It uses less water than a standard shower head, which helps reduce water bills and environmental impact. However, some people find that very low flow shower heads may not provide a strong enough flow of water for their preference.
There are several reasons for low water pressure in the shower. The plumbing might have a closed valve, a low-flow showerhead, or a faulty pressure regulator, to name a few culprits.
The problem is how bacteria can enter the water system with lower pressure, and it doesn't get torn away as easily. When low water pressure happens, and you don't have a main backflow preventer, this can suck the things into the water from the sewer system and lead to backup problems.
It's important to maintain your home's water pressure within an acceptable range. The ideal water pressure ranges between 40 and 80 pounds per square inch, with the recommended home water pressure at 60 psi.
High Water Bills: Physical problems aren't the only issues caused by high water pressure. If your pressure is too high, you could also see an increase in your water bills. If you're trying to save money on utilities, high water pressure could be costing you.
Information regarding the minimum flowing pressure required at water outlets for adequate, normal flow conditions consistent with satisfactory fixture usage and equipment function may be deemed to be as follows: 15 psig minimum flowing for all water supply outlets at common plumbing fixtures, except 20 psig minimum ...
Typical water pressure should fall between 45-80 PSI, and below 40 PSI is considered low.
Water Pressure Readings
Normal water pressure is generally between 40 and 60 PSI. Most homeowners prefer something right in the middle around 50 PSI. Once you measure the water pressure in your house, you can adjust it to a setting that is ideal for all family members and household uses.
Pressures below 20 PSI are considered “flat” and dangerous to drive on.
To fix these problems, you'll need to seek assistance from an experienced plumber who will identify the cause of the low water pressure and determine the best way to remedy the problem.
Head outside to the water spigot, remove the hose, and screw the test gauge onto the spigot, ensuring the face of the gauge is visible. Turn the spigot valve on and check the reading. This will indicate the amount of pressure coming into your home (from a public utility system or a well).