What's the Difference Between Water Flow and Water Pressure?
Water pressure and water flow are often confused, but they're not quite the same thing. The main differences between the two are:
- Water pressure refers to the force pushing water through your pipes, measured in pounds per square inch (psi).
- Water flow is the volume of water that actually comes out of your fixtures, usually measured in gallons per minute (gpm).
You can think of it like this: pressure is the push, and flow is the amount of water delivered. High pressure with blocked or narrowed pipes can still result in very low flow. On the flip side, if your municipal supply is weak, you may have both low pressure and low flow throughout the home.
Understanding the difference is key because the solutions are different. Cleaning a showerhead may help with local flow problems, but if your pipes are undersized or corroded, you'll need a more permanent fix. We have several articles about low water pressure and its common causes.
What Causes Low Flow of Water?
Several factors can reduce water flow in your home. Some are temporary, while others indicate long-term plumbing issues:
- Mineral buildup: In areas with hard water, calcium and limescale can accumulate in fixtures and inside pipes, narrowing the space for water to pass through.
- Clogged or failing fixtures: Aerators, cartridges, and showerheads can trap sediment and debris.
- Partially closed valves: After maintenance or repairs, valves may not be fully reopened, cutting flow.
- Pressure regulator problems: A failing pressure-reducing valve (PRV) can disrupt flow across your entire home.
- Municipal supply issues: Sometimes, the problem isn't in your home at all. Work on city water mains or higher-elevation properties can cause low water flow.
- Improperly sized pipes: If your plumbing wasn't updated during a remodel or addition, your pipes may simply not be wide enough to keep up with demand.
The first step in addressing low water flow is figuring out whether the issue is isolated to one fixture, one part of the house, or the entire system. Widespread low flow usually points toward aging pipes or problems with your main supply line and will require a more serious fix.
Can Old Pipes Cause Low Water Flow?
Old pipes are one of the most common reasons homeowners experience persistent low flow.
Galvanized steel pipes, which were once standard, are particularly prone to corrosion. Over decades, the zinc coating wears away, leaving the steel exposed. The inside of the pipe rusts, gradually reducing the diameter until water can barely pass through. This doesn't just restrict flow—it can also send rusty water and metallic-tasting sediment into your taps.
Copper and other older materials can also develop internal scaling, especially in hard water areas. You may notice:
- Low flow at multiple fixtures (not just one faucet or shower).
- Rusty or discolored water, especially on the hot side.
- Fluctuating flow when multiple fixtures run at once.
Sometimes, only a single pipe is affected, even in otherwise healthy plumbing. This can happen when one section of piping is more corroded, kinked, or partially blocked by debris, mineral deposits, or a malfunctioning valve. Isolated low flow is often easier to fix than a systemic issue, but it can still indicate an aging pipe that may need repair or replacement. Unfortunately, once pipes reach this stage, there isn't a reliable long-term fix other than repiping.
How Do I Fix Low Water Flow in My House?
Fixing low water flow depends on the root cause. For isolated issues, simple maintenance can often restore normal water flow.
Cleaning aerators, showerheads, and faucet cartridges can remove trapped sediment or mineral deposits that restrict flow. It's also important to check shut-off valves throughout your home, ensuring they are fully open and not partially closed after maintenance or repairs.
If you notice a sudden drop in water flow, inspect your water meter with all taps turned off. If the meter continues to move, it could indicate a hidden leak under your slab or behind walls.
Temporary problems, such as debris from municipal work or partially blocked water mains, can also reduce flow, and flushing pipes or cleaning fixtures may resolve these short-term issues. However, if low flow affects multiple fixtures throughout the house, the problem is likely systemic. Aging pipes, corrosion, mineral scaling, or undersized plumbing can reduce flow across the entire home.
In these cases, a repipe is often the most effective long-term solution. Replacing old pipes with modern PEX or copper tubing restores strong, consistent water flow, improves water quality, and eliminates the need for frequent repairs associated with deteriorating plumbing.
A professional repipe ensures that your home maintains reliable water flow for decades to come. Contact us to have one of our local repipe consultants explain your repipe options and provide a consultation and quote, either in-home or remotely.
Get your free estimate today
With over 75,000 repipes completed, we've perfected our One-Stop Repipe™ for your home.
Get a Quote for Repiping Pipes That Cause Low Water Flow
Here at Repipe Specialists, we've replaced the plumbing in over 75,000 homes since 1991, and many of our customers report noticeable improvements in water flow throughout their homes after a repipe. Low-flow problems, whether it's slow-filling sinks, trickling showers, or weak hot water, are often completely resolved once old, corroded, or undersized pipes are replaced. We often exceed their expectations in the following areas:
- Speed: Our repipe crews typically complete a repipe in a day, returning on another day for wall patching.
- Convenience: Through our One-Stop Repipe™ Process, we handle everything from permits, to wall patching, to inspections.
- Cleanliness: Our crews are trained to protect your home while working (we cover all surfaces with protective sheeting), and to clean up fully at the end of each day.
- Peace of Mind: Repipe Specialists is a fully licensed plumber in every state we operate in, and we back all of our repipes with a lifetime warranty.
- Financing Programs: To help take the sting out of unplanned repipe expenses, we offer several financing programs.
- Price: As a specialist that performs hundreds of repipes a week, we can deliver high-quality repipes at a lower cost versus generalist plumbers. We have an article that covers repipe cost factors in detail. Our quotes typically range from $4,500 to $15,000 depending on the size and complexity of your project.
Schedule a free in-home consult, and one of our local repipe specialists will walk you through your options and provide a written, fixed-price quote. Upgrade your pipes and say goodbye to low water flow for good.