Your shower lost its push, the kitchen faucet dribbles, and the washing machine takes twice as long to fill. When pressure drops across the whole house at once, people assume the worst: a hidden leak, a re-pipe, a big bill. Most of the time it is not that. After years of chasing low pressure on Front Range homes, we check these causes in a specific order, most likely first, because two of the six are free to rule out before anyone touches a pipe. This is that order, what each one feels like at the tap, which you can check yourself, and which is a call.
The single most useful thing you can do before reading further takes thirty seconds: find your main shutoff valve and confirm its handle is fully open. We will explain why below. If you would rather we trace it, call (720) 880-8064 and we measure PSI at multiple points before we quote anything.
Why is my water pressure low all of a sudden?
Sudden whole-house pressure loss almost always traces to one of six causes, and on Denver Metro homes they do not show up with equal odds. A failed pressure-reducing valve and a partially closed main or meter valve account for most of the calls we run, which is why we check those two first. The rest, corroded supply lines, a municipal pressure-zone swing, sediment at the water heater, or a hidden leak, come after. The tell is almost always the same: if every fixture in the house got weak at once, the problem lives at or near where water enters the house, not at any single faucet.
Here are the six, in the order we actually work them on a Front Range home:
1. A failed pressure-reducing valve (PRV). The most common cause by a wide margin. 2. A partially closed main or meter valve. The cheapest to fix, often free. 3. Corroded galvanized or aging supply lines in pre-1970 housing stock. 4. A municipal pressure-zone swing from the water utility. 5. Sediment or flow restriction at the water heater. 6. A hidden slab or supply-line leak.
The next sections take the top causes in order. The point of working them this way is that you rule out the free stuff before you pay anyone to open a wall.
Pressure reducing valve failure signs: the number-one cause
A pressure-reducing valve sits on your main line and knocks street pressure, often 80 to 150 PSI on the Front Range, down to a safe household range. The brand standard most fixtures are built for is roughly 40 to 60 PSI. When a PRV fails, it usually fails low: it clamps down and drops the whole house to 20 to 35 PSI, and it does it gradually over weeks or all at once. A PRV is a wear part. It does not last forever, and ours work hard against the high street pressure common in metro pressure zones.
The signs that point at a PRV before anything else:
"When a whole house drops to the mid-20s PSI and the street side still reads 90-plus at the hose bib, the PRV is the suspect nine times out of ten. We confirm it with a gauge on both sides before we ever recommend replacing it."
This is the one most DIY guides get wrong by telling you to just adjust the screw on top. On a valve that has actually failed, adjusting it does nothing but mask the reading for a day. A failed PRV gets replaced, not tweaked, and it is a permit-and-pressure-check job we fold into a flat rate. We handle it the same way we approach any pressure-reducing valve and main shutoff replacement: confirm the fault with a gauge first, then quote the total. Think your PRV is the culprit? Call (720) 880-8064 and we will measure it before we say a word about price.
The free check: your main and meter valves
Before you spend a dollar, rule out the cheapest cause on the list. A main shutoff valve or a meter valve that is not fully open mimics every symptom of serious pipe failure, and we find a partially closed valve more often than anyone would guess, usually after a recent repair, a water heater swap, or someone shutting the water off and not reopening it all the way.
Here is the thirty-second check, and it is genuinely DIY:
If the valve was the problem, you just fixed your pressure for free, and we are glad. If it is fully open and the pressure is still weak, you have ruled out the easy one and narrowed the field. That is exactly the process we would run in your driveway, so running it yourself first saves everyone a step.
Corroded supply lines in older Front Range homes
If the valves are open and the PRV checks out, the next suspect is the pipe itself, and in the Denver Metro the age of the house tells you a lot. Pre-1970 Front Range housing stock was commonly plumbed with galvanized steel supply lines. Galvanized corrodes from the inside out. The interior scales up with rust and mineral deposit until the usable diameter of a 3/4-inch pipe is choked down to a pencil-width channel, and the water simply cannot move through it fast enough. The pressure at the main can read fine while the flow at the fixtures is strangled.
"On a pre-1970 home where the pressure reads normal at the hose bib but every fixture still trickles, we are usually looking at galvanized pipe that has corroded its own diameter down to nothing. That is a flow problem, not a pressure problem, and a new PRV will not touch it."
A few things we look for that separate a corroded-pipe problem from a PRV problem:
'70s and '80s builds have a different suspect: polybutylene, the gray flexible supply line of that era, which fails at its fittings and degrades over time. Our replacement standard for either one is PEX-A, because it tolerates Front Range freeze-thaw cycling and pressure swings far better than the rigid galvanized or brittle poly it replaces. We never recommend a full re-pipe on the age of the house alone, though. We confirm the actual condition of the pipe before we quote. That is the core of how we approach corroded galvanized supply lines in older Front Range homes: diagnose the real restriction, then replace only what is failing.
Water pressure repair in Denver: the causes we check last
The top three causes cover most calls. Three more round out the list, and they are the ones worth knowing so you can tell whether you even have a plumbing problem.
A municipal pressure-zone swing
Sometimes it is not your house at all. The water utility runs the metro in pressure zones, and pressure can dip during peak-demand hours or after a main break or hydrant flush nearby. The quick test is the one we would ask you to run anyway: call two neighbors on different parts of your block and ask if their pressure feels weak too. If the whole block is down, the problem is upstream of your meter, it is the utility's responsibility, and no in-home work will fix it. If only your house is affected, the problem lives between your meter and your fixtures.
Sediment and flow restriction at the water heater
If your cold pressure is fine but the hot side is weak, suspect the water heater before the house. On our 12-to-17-grain water, mineral sediment settles in the tank and scale builds at the hot outlet and the inlet nipples, restricting hot-water flow specifically. A hot-only pressure complaint is a strong clue the issue is the heater or its connections, not the main supply.
A hidden slab or supply-line leak
This is the one people fear first and we check last, because it is the least common cause of a gradual whole-house drop. A significant leak between the meter and the house, or under a slab, bleeds off pressure before it reaches your fixtures. The tells are different from the other causes: a water bill that climbed with no change in use, the sound of running water with everything off, a warm spot on a slab floor (a hot-line slab leak), or unexplained damp ground along the supply run. If you see those alongside the pressure drop, that moves a leak up the list fast, and it is a locate-and-repair call, not a DIY one.
The reason we work the list in this order is simple: it goes cheapest-and-most-likely to most-involved. Guessing out of order is how a homeowner ends up paying for a new PRV when a half-closed valve was the whole story, or paying for a leak search when a corroded pipe was choking the flow the entire time. We measure PSI at multiple points and match the readings to the cause before we quote. That is the whole method, and it is covered start to finish on our page for diagnosing low water pressure across the Denver metro.
Still weak after you checked the valves? Call (720) 880-8064 and we will trace it to the source. You know the total before we pick up a wrench.
Frequently asked questions
What is normal house water pressure in PSI?
Residential plumbing is built to run in a 20 to 120 PSI range, and the target most fixtures are happiest at is roughly 40 to 60 PSI. Below about 40 PSI, showers feel weak and appliances fill slowly. Much above 80 PSI and you are stressing fixtures, connections, and the water heater, which is exactly why homes on high-pressure metro supply have a pressure-reducing valve on the main to hold the house in range. The fastest way to know your actual number is a gauge threaded onto an outside hose bib. A reading in the 20s or low 30s house-wide, with adequate pressure out at the street, usually points at a failed PRV.
Is low pressure at one faucet the same problem as low pressure in the whole house?
No, and telling them apart is the most useful first step. If only one faucet or shower is weak, the problem is local to that fixture: a clogged aerator you can unscrew and rinse, a worn cartridge, or a partially closed angle stop under the sink. If the pressure is weak at every fixture in the house at once, the problem is at or near the point of entry: the pressure-reducing valve, the main or meter valve, or a corroded supply main. Whole-house loss is what this page covers. A single weak fixture is usually a quick local fix you can often handle yourself before anyone needs to come out.
Get your pressure diagnosed, not guessed
Deft Plumbing is licensed, bonded, and insured in Colorado, and we serve the full Denver Metro along the Front Range, from Aurora and Lakewood to Arvada and Brighton. Whether your pressure drop is a half-closed valve you can reopen in thirty seconds, a failed PRV that needs replacing, or corroded galvanized pipe in a pre-1970 home that has choked its own flow, the next step is the same: measure the actual readings before anyone quotes a dollar.
Call (720) 880-8064 or read how we handle diagnosing low water pressure across the Denver metro. We diagnose first and quote the total before we touch anything. No hourly surprises.