Start with the actual machine
A pressure washer needs a suitable incoming water supply as well as compatible equipment on its high-pressure side. Its advertised output ratings do not establish what the inlet can accept.
Look up the exact model. The SIMPSON CM60976 manual, for example, lists water-supply flow and pressure conditions separately from output terminology. Cat Pumps' inlet checklist likewise directs readers to individual pump specifications. These are manufacturer instructions for the equipment concerned, not universal settings or worldwide legal standards.
Assess the source and the path to the inlet
SPITWATER's Australian guidance distinguishes mains, tank and bore-water supplies. It calls for clean water delivered continuously within the machine's required flow and pressure range, and discusses hose restrictions and water quality.
That makes the connected arrangement part of the assessment. A tank is not automatic proof of adequate supply, and a strong-looking stream is not a substitute for the required checks. Ask the manufacturer or dealer how to assess your source, supply hose and filtration together; use the limits for your equipment rather than another brand's example figures.
A symptom does not identify the cause
Cat Pumps lists supply restrictions and competing water demand among possible problems. Its troubleshooting guide also lists pressure controls, seals and valves as possible causes of fluctuating pressure. Pressure variation alone therefore does not establish cavitation or an inlet fault.
When the cause or suitable operating conditions are uncertain, follow the machine's instructions and obtain manufacturer or authorized-service advice before continuing. This reference is not a procedure for adjusting controls or opening a pump.
Give the supplier a useful question
Our suggested preparation is to collect the machine and pump identification, the relevant manual, source type and a description of the hose and filter arrangement. Note other equipment sharing the source and any observed problem without assigning a diagnosis.
Ask which supply measurements and assessment method the manufacturer requires, and who should perform them. Resolve compatibility before operation. An inlet assessment is one part of setup; the machine's other operating and safety requirements still apply.
Sources & references
- Inlet Condition Check-List, PN 993418 Rev C, February 2020 — Cat Pumps. Checked October 28, 2026.
- Troubleshooting: pump and system symptoms — Cat Pumps. Checked October 28, 2026.
- Why Correct Flow Rate and Water Inlet Setup Matter for Pressure Washing — SPITWATER Australia. Checked October 28, 2026.
- CM60976 Use and Care Manual, part 7111613, English Rev. 8, June 2022 — SIMPSON. Checked October 28, 2026.