Blog » Troubleshooting

How to Unclog Nozzles, Filters, and Inlet Screens

Weak spray, surging pressure, or a machine that will not build pressure at all? A single grain of sand in the wrong place can do that. Here is how to find and clear every clog point in the system.

A pressure washer is a precision water circuit: every gallon that leaves the nozzle had to pass through the spigot, the garden hose, the inlet screen, the pump, the high-pressure hose, and finally a tiny precision orifice. A clog at any one of those points chokes the whole system — and the symptoms (low pressure, pulsing and surging, or no pressure at all) rarely tell you which point it is. This guide walks the circuit from nozzle back to spigot so you find it fast.

Depressurize First: The Non-Negotiable Safety Step

Before you unscrew, unplug, or poke anything on a pressure washer rental: shut the machine off, turn off the water supply, and squeeze the trigger until water stops flowing completely. Trapped pressure can launch a nozzle tip like a projectile or inject water through skin — high-pressure injection injuries are surgical emergencies that look deceptively minor at first. Wear safety glasses for all of the following steps, and never put your fingers in front of a nozzle orifice to "feel" for a clog while the system could be pressurized.

Clearing a Clogged Nozzle Tip

The nozzle orifice is the smallest passage in the system — often under 2 millimeters — so it clogs first and most often. Symptoms: pressure drops suddenly mid-job, the fan pattern goes lopsided, or the machine surges.

1. Depressurize the system completely (see above).
2. Remove the nozzle from the quick-connect on the wand.
3. Hold it up to the light and look through the orifice from the back (inlet) side. You will often see the offending grit.
4. Flush it backward — run water from a garden hose through the back of the nozzle, opposite the normal flow direction. This alone clears most clogs.
5. If grit remains, use the nozzle cleaning tool (the thin wire tool in your rental kit). Push it gently straight through from the back side. Use only the proper tool — a hardened pin or drill bit can score or enlarge the precision orifice, permanently ruining the spray pattern.
6. Reinstall, repressurize, and test on concrete before pointing it at your project surface.

If the same nozzle clogs repeatedly, the debris is coming from upstream — keep reading.

Cleaning the Pump Inlet Screen

Where your garden hose screws into the pump, a small cone or disc screen catches debris before it reaches the pump valves. When this screen loads up with sand, rust, or teflon-tape shreds, the pump starves — classic symptoms are gradual pressure loss and surging that gets worse over the day.

1. With everything off and depressurized, unscrew the garden hose from the pump inlet.
2. Extract the screen with needle-nose pliers or a fingertip.
3. Rinse it under a tap and pick out embedded grit. Hold it to the light; the mesh should be clearly visible.
4. Check the hose washer in the coupling while you are there — a disintegrating rubber washer sheds crumbs straight into the screen.
5. Reinstall the screen, reconnect the hose, and purge air before restarting (trigger squeezed, machine off, until water flows steadily).

Inline Filters and Detergent Strainers

Many rental setups add extra filtration you might not know about. If your rig includes a soft wash or downstream injection setup, there is a small strainer on the end of the chemical pickup hose sitting in your soap bucket — when it clogs with crystallized chemical or debris, soap stops drawing (though water pressure stays normal). Pull it out, rinse it, and make sure it is fully submerged during use. Some machines also have an inline filter in the high-pressure line or at the wand inlet; these are less common on rentals, but if your unit has one, it unscrews for rinsing the same way. When in doubt, ask us at pickup where every filter on your specific unit lives — we would rather show you in 30 seconds than have you discover them mid-job.

Don't Overlook the Garden Hose and Spigot

Clogs love to hide at the very start of the circuit. Unscrew the garden hose from the spigot and check the spigot's own screen or vacuum breaker for mineral crust. Run the spigot wide open into a bucket for 30 seconds — you are flushing rust and sediment out of the house plumbing before it reaches your filters. Then check the hose itself: look through it toward a light for internal delamination (a collapsed inner liner acts like a flap valve), and flush it the same way. Old, sun-baked hoses shed rubber particles internally; if your hose is the debris source, no amount of nozzle cleaning will keep you running.

Preventing Clogs for the Rest of Your Rental

• Flush before connecting: run the spigot and garden hose for 30 seconds before hooking up the washer, every time you move to a new water source.
• Keep hose ends off the ground: when disconnected, cap the ends or hold them up — dragging an open coupling through dirt loads it with grit.
• Use the inlet screen: never run without it "for better flow." That screen is the only thing between pump valves and a $300 repair.
• Strain your chemicals: mix detergents in a separate bucket and pour through a paint strainer into the soap tank; undissolved granules are a top clog source.
• Drain and coil cleanly at day's end: relieve pressure, disconnect hoses, and store couplings capped so debris cannot enter overnight.

Nozzle Orifice Reference Chart

Machine size	Typical orifice	What clogs it fastest
Electric, up to 2000 PSI	~1.5–2.0 mm	Fine sand, rust flakes
Gas, 2700–3300 PSI	~2.0–2.5 mm	Teflon tape shreds, hose rubber
Commercial, 4000+ PSI	~2.5–3.5 mm	Chemical crystals, scale
Surface cleaner nozzles	~1.0–1.5 mm each	Anything — smallest orifices in the system

Smaller orifice, faster clog — which is why surface cleaner nozzles deserve the most diligent upstream filtering.

When to Stop and Call the Rental Shop

Stop and call us if pressure does not return after you have cleared every point in this circuit, if you find metal shavings or rubber chunks in the inlet screen (that signals internal pump or hose breakdown), if a nozzle orifice is visibly deformed or enlarged, or if the pump makes grinding noises suggesting debris got past the screen into the valves. Do not disassemble the pump head or remove check valves — that is sealed shop territory, and debris-damaged valves need professional reseating. Tell us where in the circuit you found debris; it helps us decide whether to swap the unit, replace a hose, or just hand you a fresh nozzle set. Clog-related downtime is almost always measured in minutes once you know the circuit — which, after this guide, you do.

Frequently Asked Questions

Can I use compressed air to blow out a clogged nozzle?

Blowing backward through the nozzle with low-pressure air is fine and often effective. Do not blast high-pressure shop air forward through the orifice — it can lodge the particle tighter. Water flushing from the back side remains the most reliable method.

Why does my nozzle keep clogging every 20 minutes?

The debris is coming from upstream. Work backward: inlet screen condition, hose interior, spigot sediment, chemical mixing. A recurring clog is a symptom — the source is always earlier in the circuit than the nozzle.

Is it okay to run without the inlet screen temporarily?

No — never. The screen is the pump's only defense against debris reaching the precision valves. Running unscreened risks valve damage that the damage waiver may not cover, since it is classified as misuse rather than wear.

My quick-connect is stuck and won't release the nozzle. What now?

First confirm the system is fully depressurized — pressure locks quick-connects. Squeeze the trigger with the machine off, then pull the collar back firmly while wiggling. If it is corroded stuck, a shot of penetrating oil and patience beats force; forcing it can damage the wand fitting.

Can hard water scale clog a nozzle?

Yes, over time mineral deposits narrow the orifice, especially with hot-water units. A vinegar soak dissolves light scale. If your area has very hard water, this is another reason to descale the whole system on schedule.

Should I carry spare nozzles on a big job?

Absolutely — it is the cheapest insurance in pressure washing. A spare matched nozzle set lets you swap in seconds and clean the clogged one at your leisure instead of losing momentum mid-job. Ask us at pickup; spares are inexpensive.