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Pressure Washers · Troubleshooting

Pressure Washer Losing Pressure: 7 Causes and Fixes

Everything you need to know about pressure washer losing pressure: 7 causes and fixes, explained plainly.

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How to fix it

Work through these in order, the most common causes come first.

  1. Start With the Basics

    Water supply: Confirm the garden hose feeding the unit is at least 5/8-inch diameter, fully uncoiled, and that the spigot is completely open. An undersized or restricted supply line is one of the most overlooked causes of low pressure. Nozzle condition: Remove the tip and check for debris or mineral buildup.

  2. Diagnosing Your Specific Problem

    Pressure drops gradually during use: likely a nozzle slowly clogging with fine debris, or the inlet filter screen becoming blocked over the course of the job. Pressure was never strong from the start: check water supply first, an inadequate garden hose diameter or partially closed spigot is a common cause of consistently underwhelming pressure. Pressure sputters or surges rather than staying low: points to trapped air in the system, or a kink somewhere in the hose intermittently restricting flow.

  3. See Also

    Pressure Washer Not Starting Pressure Washer Leaking at the Hose Connection Pressure Washers Buying Guide

Start With the Basics

Water supply: Confirm the garden hose feeding the unit is at least 5/8-inch diameter, fully uncoiled, and that the spigot is completely open.

An undersized or restricted supply line is one of the most overlooked causes of low pressure.

Nozzle condition: Remove the tip and check for debris or mineral buildup.

A partially clogged nozzle opening restricts flow even when everything else is working correctly.

Trapped air: After connecting or reconnecting hoses, squeeze the trigger with the water on but the unit off for 30 to 60 seconds to purge air before starting the motor.

Diagnosing Your Specific Problem

Pressure drops gradually during use: likely a nozzle slowly clogging with fine debris, or the inlet filter screen becoming blocked over the course of the job.

Pressure was never strong from the start: check water supply first, an inadequate garden hose diameter or partially closed spigot is a common cause of consistently underwhelming pressure.

Pressure sputters or surges rather than staying low: points to trapped air in the system, or a kink somewhere in the hose intermittently restricting flow.

Pressure was fine last use, weak this time: check the nozzle for new buildup and the inlet filter screen, sediment accumulation is often gradual and shows up as a sudden-feeling drop.

None of the above resolves it: the pump seals or unloader valve may be worn, more likely on an older unit or one that's seen heavy use, and typically requires professional repair or replacement.

See Also

Pressure Washer Not Starting Pressure Washer Leaking at the Hose Connection Pressure Washers Buying Guide

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Answers

Frequently asked questions

Why does my pressure washer lose pressure after a few minutes?

The most common causes are a partially clogged nozzle, air trapped in the pump or hose, a kinked hose restricting flow, or an inadequate water supply from the garden hose feeding the unit. Start with the water supply and nozzle before assuming a pump problem, since those two account for most cases.

Can a dirty nozzle really cause a big pressure drop?

Mineral deposits, dirt, or small debris partially blocking the nozzle opening restrict water flow and can noticeably reduce pressure, even though the pump itself is working fine. A nozzle that looks clean can still have partial buildup inside the tip that's not visible without close inspection or a cleaning needle.

Why does my pressure washer have good pressure at first but then drop off?

This pattern usually points to air trapped in the system after startup, a nozzle gradually clogging as it draws in fine debris, or the garden hose supply struggling to keep up once the pump has been running for a few minutes. It can also indicate the inlet water filter screen is partially blocked and worsening over the course of use.

Is low pressure a sign the pump is failing?

It can be, but pump wear is usually the last thing to check, not the first. Worn pump seals or a failing unloader valve do cause permanent pressure loss, but these are less common causes than a clogged nozzle, inadequate water supply, or trapped air, which together explain the majority of pressure complaints.

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