Why is my water pressure low all of a sudden?
A sudden drop usually means something changed: a valve got bumped, a leak opened up and is bleeding pressure off elsewhere in the house, or a water heater or fixture shutoff is stuck part-way. A gradual drop over months or years, especially in a house built before the 1970s, is almost always galvanized supply pipe narrowing from the inside as rust and mineral scale build up on the pipe wall. The pipe can look fine from outside and still be down to a pencil-width opening inside.
Is it the city or my house?
Portland's public water pressure is generally strong and consistent across the metro, so if pressure is only low at your address, the cause is on your side of the meter. We check pressure right at an outside hose bib first — that tells us what's actually arriving at the house before it hits your plumbing. If that reading is normal but pressure drops inside, the restriction is internal: old pipe, a clogged aerator or cartridge, or a valve that isn't fully open.
Why is my pressure too high, and does it matter?
Portland's hilly terrain and the way the water bureau's pressure zones are laid out mean some properties, especially lower in a given zone or near a booster station, run high straight from the main. Pressure over about 80 psi stresses every fitting, supply line, and appliance connection in the house, and it's a common reason water heaters and washing machine hoses fail early. A pressure-reducing valve (PRV) brings it down to a safe range. If your house doesn't have one, or the one it has has failed open, that's usually the fix.
What's causing the banging or hammering in my pipes?
That knock when a faucet or washing machine valve shuts off is water hammer — water moving through the pipe suddenly stopped, sending a shockwave back through the system. It's common in older Portland houses without air chambers or with chambers that have waterlogged over time, and it also shows up after a PRV fails or after a fixture replacement changed the flow characteristics. Arrestors installed near the offending fixture usually solve it; a failing regulator sometimes needs replacing outright.
What affects whether this is a quick fix or a bigger job
- Age and material of the supply line. Galvanized pipe restricting flow is a pipe problem, not a valve problem — patching one fixture won't fix the whole house.
- Whether a PRV is present and its condition. Some older Portland homes were plumbed before PRVs were standard and never had one added.
- Number of fixtures affected. Pressure low at one sink usually means a local clog or cartridge. Pressure low everywhere points upstream, toward the main line or the meter.
- Access. Crawlspace houses common in inner Portland neighborhoods versus slab construction in newer Beaverton and Hillsboro subdivisions change how much digging or crawling is involved.
- What else is going on. A leak, a partially failed valve, or corrosion inside a water heater can all masquerade as a pressure problem.
How the visit goes
We test static pressure and running pressure, check the PRV if one exists, and walk the accessible supply line looking for the transition points where galvanized meets copper or PEX — those joints are where corrosion problems usually show up first. If the cause is a valve or regulator, we can often replace it the same visit. If it's failing galvanized pipe, we'll show you what we're seeing and talk through whether a partial repair or a full repiping makes sense for the age of the house.
What's specific to Portland houses and water
A large share of Portland's housing stock — especially in North, Northeast, and Southeast neighborhoods built before 1960 — was originally plumbed in galvanized steel, and that pipe has a service life measured in decades, not indefinitely. Portland's water is relatively soft, which is easier on pipe than hard water, but soft water still corrodes galvanized steel from the inside over 40-60 years, and most of that original pipe is now well past that mark. Combine that with a hilly service area where pressure zones vary block to block, and pressure complaints here are rarely one simple cause — which is why we test rather than assume.
Why Sheltons Construction
We're a licensed Oregon plumbing contractor working the Portland metro every day, and pressure problems come up constantly on service calls that started as something else — a water heater replacement, a remodel, a leak. We test at the source, explain what we find, and quote the actual repair instead of a menu of parts. If the issue turns out to be a related job — a failing water heater, a hidden leak, or a sewer or drain issue behind a wall — we'll tell you plainly instead of only fixing what was on the ticket.
What to do now
If pressure dropped suddenly and you can hear or see water running somewhere it shouldn't, shut off the main and call. If it's a slow decline or a hammering noise that isn't an emergency, request a quote and we'll get a diagnostic visit scheduled. For anything active — a burst line, no water at all — see emergency plumbing.
We work pressure and pipe issues throughout Portland, Beaverton, Hillsboro, Gresham, Tigard, Tualatin, Lake Oswego, West Linn, and Oregon City.
Related services: drain cleaning, hydro jetting, sewer camera inspection, sewer line repair, and tankless water heaters, which are especially sensitive to incoming pressure and flow rate. More common questions are answered on our FAQ.