What Is Low Water Pressure and How to Measure It?
Normal residential water pressure should fall somewhere between 40-60psi. Anything above 80psi is too high, can damage appliances, and could increase the likelihood of pipe leaks. Anything below 30psi is too low, may prevent some appliances from functioning properly, and will make for some long showers to get clean!
It is easy to measure your water pressure with inexpensive pressure gauges readily available at any hardware store. These pressure gauges can be attached to any of three common fixtures in your home:
- Outdoor hose spigots and hose bibs
- The supply connection to your washing machine
- The drain at the bottom of your hot water heater
Low water "pressure" vs low water "flow":
Many people refer to having low water pressure in their home, when they really mean they have low water flow at one or more outlets like a shower or sink. You can actually have quite high pressure in your pipes, but if there is a restriction somewhere, you would experience a reduction in flow when the water is running.
For this reason, if you are checking your water pressure, you should measure both your static pressure (when all outlets are closed), and your dynamic water pressure (when one or more outlets are open, and the water is running). Ideally, if possible, you should also check multiple outlets around your home.
Even if you have very obviously low water flow at a particular outlet, it can still be useful to test your static water pressure, as it will help identify the cause of your low water flow, as we cover in the next section of this article.
What Are the Common Causes of Low Water Pressure?
In the remainder of this article, we will use these terms:
- Systemic low water pressure: issues have existed over a long period of time, either throughout your home or in specific locations.
- Temporary low water pressure: issues have arisen relatively quickly and recently, on one or more outlets in your home.
Systemic Low Water Pressure Causes:
Here are the possible causes of long term water flow and low water pressure in your home, along with their associated symptoms and fixes:
Old Galvanized Plumbing
- Your home is 40+ years old
- Most/ all water outlets have low flow
- Water may look rusty or taste metallic
- Low flow tends to be worse on hot water outlets
Your plumbing has likely reached the end of its serviceable life. Read about replacing your galvanized pipes in the next article section. We'll cover what the process entails, along with how much it might cost.
Mineral Buildup in Pipes and Outlets
Old galvanized iron pipe can build up significant rust scale internally, causing water flow restriction.
However, ANY type of plumbing can build up mineral scale in pipes, fittings, and outlets; particularly in hard water areas. This is particularly true in plumbing systems with a lot of connections and bends, like CPVC or copper piping.
- You are in a hard water area, and home is 20+ years old.
- Streaks and scale on fittings and sinks are a sign of hard water.
- Flow rates vary by fixture and area.
- Outside hose bibs with no filter screens may have high flow, but internal fixtures with filter screens are slow.
- Outlets that are used less, can be worse than high use outlets.
Start with ensuring fixtures (like a faucet) are cleaned of sediment & scale, and any filter screens are flushed out. Older fixtures may need to be replaced.
If that doesn't work, and you have copper piping that has been in place for 20+ years in a hard water area, it is possible that the entire system needs to be repiped.
We have many customers who repipe from copper to PEX tubing. PEX tubing comes with many benefits over other pipe types: in the context of mineral buildup and low pressure, a key benefit is that PEX tubing can be run in continuous lengths from a central manifold direct to outlets. This means fewer connections and tight bends: resulting in higher flow and less mineral buildup.
If you'd like to learn more about a PEX repipe, contact us a for a free repipe consult and quote.
Restricted Flow in Main Supply to House
If you have restricted water flow somewhere between the water main in the street and the entry into your house, it will affect your flow and water pressure equally throughout your house.
If your neighbors tend to not have water pressure problems, then it is unlikely that the problem is low pressure with the municipal supply.
It is possible that one of the shut-off valves in your water supply is partially closed. Most homes have a shut-off valve near where the water supply enters the home (and it is important to know where this is, in case you need to shut off water quickly). There are also usually shut-off valves on either side of the water meter. By visually looking at these valves, you can normally determine if they are partially closed.
Note that in most municipalities, you should not attempt to operate the valve on the city side of the meter.
If all the valves seem to be fully open, it is possible you need to have your main line replaced. Just like the plumbing in your home, the main service line can get blocked by rust or mineral build up. If your home has been significantly remodeled over the years, there's a possibility that the service line needs to be a wider diameter to accommodate the higher water volume demand.
One of our local estimators would be happy to consult with you to help determine the cause of your low water pressure. They can also provide you a free, no obligation quote to replace your main water line. Call 800-216-0132, or send us a message, to schedule a consult or quote.
Improperly Sized Piping
The diameter of a pipe or tube, determines its capacity for carrying water at normal flow rates. If a pipe is undersized for the water demand it services, this can result in low water flow at outlets. Building codes determine minimum pipe diameters, for an expected volume of demand; and it is unlikely that your home had undersized pipes upon original construction.
However, if your home has been remodeled and extended, it is possible that either the new construction was undersized, or that extra demand outstripped the carrying capacity of parts of your plumbing system. This can all be exacerbated by any corrosion and scale build up in old pipes.
Unless it is the main service line that is undersized, you'd most likely notice reduced flow in specific areas of your home (in remodeled areas, sections furthest from the main line).
A plumber would need to evaluate your plumbing system, and determine if any sections of your plumbing are undersized. If it is, that section will need to be replaced.
A note of caution: if you have a pressure reducing valve, many homeowners (or plumbers) will increase the water pressure, to compensate for undersized (or clogged) pipes. This might temporarily alleviate flow issues, but can significantly increase the risk of pipe leaks or appliance damage. Any static pressure over 80psi can be dangerous.
This is another area where we'd be more than happy to help you troubleshoot your low water flow problems: contact us for a free consult. Repipe Specialists is a fully licensed plumbing contractor, in every state we operate in.
Systemically Low Pressure Municipal Supply
- More common if you are at a higher elevation
- Your neighbors are all likely to have the same issue
- Upper floor fixtures might have much lower flow than ground floor
A booster pump to increase pressure to your whole home, or parts of your home (like upstairs), is one option. However, this is not necessarily a drop-in easy fix, and you would want to first ensure the cause is truly from non-temporary main supply low water pressure.
It is also possible that one of the other system low pressure issues listed in this article is contributing to your low pressure issue, and resolving that first, might provide you with sufficient flow without adding booster pumps (which may need to be paired with a pressure storage tank).
We don't install booster pumps/systems - but we can help you determine if a repipe can give you sufficient water flow. Many homeowners are surprised by how affordable a repipe can be.
Faulty Water Pressure Regulator
In areas where municipal water supply has very high pressure, homes are fitted with water pressure regulators, often referred to as a pressure reducing valve (PRV), which reduce the water pressure into your home. The valves typically have a serviceable life of 10 to 15 years.
If you have a PRV related pressure issue, any problems would be common throughout all outlets in your home.
Some PRV problems may also cause fluctuations in your pressure throughout your home.
- The PRV pressure setting may be too low
- Shut off valves near the PRV may be partially closed
- You may need to replace your pressure regulating valve
Here at Repipe Specialists, we specialize in whole home repipes, and don't offer general plumbing services (such as replacing a PRV). However, we do maintain a list of local, trusted referrals in many areas. Feel free to contact us, and we'd be happy to provide a referral.
Hot Water Heater Tank Issues
- Low pressure on hot water outlets only
- All hot water outlets have low flow
There are multiple reasons hot water heaters (tank-based systems) can be associated with low pressure. It could be as simple as a partially closed supply valve to the water heater, or a kinked supply/outlet pipe (if your hot water heater uses flexible pipe connections).
You may have sediment build up in the tank. Manufacturers recommend you flush your water heater at least annually (more frequently in hard water areas). This is a relatively easy DIY task, and the internet has many videos on how to do this.
Hot water heaters have limited service lives. If your heater is more than 10 years old, there is a good chance it has started to corrode significantly internally, and needs replacement.
Well Water System Malfunctioning
If you are on a well system, there are multiple reasons you may have low pressure, depending on the type of system you have (gravity fed vs pressure tank). We won't cover all the well related issues here: it is best to have a well system specialist regularly service and inspect your well system.
How to Fix Low Water Pressure Caused by Old Galvanized Pipes
Here at Repipe Specialists, replacing old galvanized pipes with new copper pipe or PEX tubing, is one of the most common services we perform. We've upgraded thousands of homes; giving homeowners clean, fast flowing fresh water.
There is no way to repair old galvanized pipe: it needs to be replaced. Doing the replacement in stages, will be more disruptive and expensive than replacing the entire system at once.
Having completed over 60,000 repipes in total, we've perfected our One Stop Repipe ™ Process: we handle everything from permits to wall patching, and your repipe is completed in 1-2 days. Our repipes also come with a lifetime warranty.
We have a 5-minute read article covering the Cost of Replacing Galvanized Plumbing.
We also offer special no interest, nothing down financing programs to take the sting out of a repipe.
How to Fix Low Water Pressure Caused by Temporary Issues
This is a list of some of the most common temporary causes of low water pressure in a home, along with possible fixes:
- Water Leak in Pipes or Slab: Of all the "temporary" causes of low water pressure, this is the one that requires the most urgent attention. If you have a water leak that causes a noticeable drop in water pressure, but you don't see where the leak is, it is probably in or under your slab foundation. It can be causing significant (but initially unseen) damage, and should be urgently investigated and fixed. Read our article about The Best Options for Slab Leak Repairs. By shutting off all outlets, and then measuring your water usage at the meter, you can determine if you have an ongoing (but unseen) leak.
- A Fully or Partially Closed Valve: There are valves throughout your plumbing system. If you've had a recent pressure drop, it may be due to a valve that has been accidentally fully or partially closed. If the pressure drop is throughout your home: starting at the street, inspect the valves at the water meter, and the main property shut-off valve. If it is hot water only, check the valves around your hot water heater. Most fixtures around the house also have their own shut-off valves.
- Water Main Outage: Most municipalities post online status updates of work-in-progress or water main breaks that might disrupt water supply in your area.
- Faulty Pressure Regulator: We discussed pressure regulators in more detail earlier in this article as a potential cause of long-term pressure issues. However, they can fail suddenly. Pressure regulator failures more typically result in high pressure: but it is possible they can result in a sudden drop in flow as well. If your regulator is more than 10 years old (less in hard water areas), it may need replacing.
- Temporary Clogging of Pipes From Silt: We've seen situations where a water utility company performed work on local water mains, causing significant silt to enter the water supply. Inspect an easy access fixture, like a shower head. If you see a lot of sand & debris behind the screen filter, then this could be the cause of low flow in outlets. As this silt (sand & small debris) works its way into your plumbing system, it can clog up some outlets. Remove & clean the various screen filters on your outlets, and thoroughly flush your plumbing system.
How Much Does It Cost To Repipe a House?
For a more in-depth review of repipe cost information, see our How Much Does It Cost To Repipe A House article.
Most of our repipes fall somewhere between $4,500 for a two-bedroom, one-bath, house, and up to $15,000 for a much larger, more complicated job. Copper repipes are more expensive than repiping with PEX tubing. All our repipes use made in the USA copper pipe or PEX tubing, and are backed by a lifetime warranty.
PEX is our most common repipe material, and is particularly popular if homeowners are looking to resolve low water pressure issues.
A Repipe Specialists local estimator would be happy to explain all your options, either in person or in a remote consult session. Schedule a free, no-obligation repipe quote.