Whole-house low pressure usually comes from a failing pressure-reducing valve, a main shutoff or meter valve that isn't fully open, corroded galvanized pipe, a utility pressure problem, or a leak in the service line. Measure the pressure with a gauge at an outside faucet, then do a meter test with everything off. Low pressure plus a moving meter points to a leak.
When every faucet and shower in the house feels weak at once, the problem is almost always on the main line, not the fixtures. That narrows it to a handful of causes, and one of them is a leak. A pressure gauge and your water meter will tell you which one you have, usually in under an hour.
One fixture or the whole house?
Start here, because it changes everything:
- One faucet or shower is weak: usually a clogged aerator or showerhead, a partly closed valve under that sink, or a problem with that fixture’s cartridge. That’s a simple repair, not a leak hunt.
- Only hot water is weak: look at the water heater: sediment, a partly closed valve on the heater, or a problem on the hot side.
- Everything is weak: the cause is on the main line. Keep reading.
Common causes of whole-house low pressure
| Cause | Clues |
|---|---|
| Utility or area problem | Neighbors have it too; main break or maintenance nearby; sudden drop |
| Main shutoff or meter valve not fully open | Pressure dropped right after plumbing work, a water heater swap or a move-in |
| Failing pressure-reducing valve (PRV) | Pressure is very low, or swings between low and very high |
| Corroded galvanized pipe | Older home, pressure has faded slowly over years, rusty water at times |
| Clogged filter or softener | Whole-house filter or softener that’s overdue for service |
| Leak in the service line | Meter moves with everything off, soggy yard between meter and house, higher bill |
| Leak inside the house or under the slab | Meter moves with everything off but stops when the house shutoff is closed; warm floors or water sounds |
Step 1: Measure the pressure
A threaded water pressure gauge costs less than a pizza at a hardware store.
- Make sure no water is running anywhere in the house.
- Screw the gauge onto an outside hose faucet or the washer connection.
- Open the faucet fully and read the gauge.
Most homes run between 40 and 80 psi, and 40–60 psi feels comfortable for most households. Model plumbing codes, such as the IPC and UPC, require a pressure-reducing valve where supply pressure is above 80 psi. If your reading is well below 40 psi, keep going.
Step 2: Check the easy things
- Ask a neighbor and check your water utility’s website or social media for outages, main breaks or hydrant flushing.
- Open the main shutoff fully. Turn it counterclockwise until it stops. A valve left partly closed after a repair is a common, free fix.
- Check the valve at the meter if you’re allowed to (some utilities don’t want homeowners touching it).
- Bypass or service a whole-house filter or softener if you have one.
Step 3: Do a meter test for leaks
- Turn off every faucet, appliance and the irrigation system.
- Watch the leak indicator on the meter for 10–30 minutes, or compare readings an hour or two apart.
- If the meter moves, water is escaping.
- Now close the main shutoff inside the house. If the meter still moves, the leak is in the buried service line outside. If it stops, the leak is inside the house or under the slab.
A service line leak big enough to affect pressure usually leaves other clues: a patch of lawn that stays soggy, sunken or greener than the rest, water near the meter, or a water bill that jumps. In central Indiana, freeze–thaw cycles, clay soil movement and tree roots are common culprits.
Step 4: If it’s not a leak
- Low reading and no leak: a failing PRV or corroded pipe is likely. A plumber can test and replace the PRV, or assess older galvanized lines.
- Pressure swings or banging pipes: often a PRV problem or a missing thermal expansion tank at the water heater.
- Low pressure at the street: your utility should confirm what pressure they deliver to your address.
Finding a leak in the service line
If the meter test points outside, don’t start digging along the whole line. Professional underground water leak detection finds it first:
- Line location traces where the pipe actually runs from the meter to the house.
- Acoustic listening along the line finds where the leak noise is loudest.
- Tracer gas finds leaks in plastic pipe that don’t carry sound well.
The spot is marked on the lawn or driveway so the plumber digs one small hole. If the leak is inside the house instead, see hear water running when nothing is on and how to find a slab leak.
Get it checked
Across Bargersville and Johnson County, including Trafalgar and Franklin where many homes have long service lines, we find leaks that cause low pressure and mark them for repair. Call us once your meter test shows water is going somewhere it shouldn’t.
Still can’t find it?
Our underground water leak detection pinpoints the leak without tearing things up, so the repair starts in the right spot.
Frequently asked questions
What is normal water pressure for a house?
Most homes run between about 40 and 80 psi, and 40 to 60 psi is comfortable for most households. Model plumbing codes require a pressure-reducing valve when street pressure is above 80 psi.
Can a water leak cause low water pressure?
Yes. A large leak, especially in the buried service line from the meter to the house, lets water escape before it reaches your fixtures. Low pressure together with a moving water meter and a soggy spot in the yard is a classic sign.
Why did my water pressure drop suddenly?
Common reasons are utility work or a main break in your area, a pressure-reducing valve that failed, a shutoff valve that was partly closed during recent plumbing work, or a new leak. Check with neighbors and your utility first, then test your own system.
How do I test my water pressure?
Screw an inexpensive pressure gauge onto an outside hose faucet or the washing machine connection, make sure no water is running in the house, and open the faucet fully. The reading is your static water pressure.