Appliance water pressure requirements are the minimum and maximum supply pressures, in pounds per square inch (psi), that a washer, dishwasher, refrigerator or ice maker is designed to handle at its water connection. They appear in installation guides because each machine's inlet valve has to open, fill and close reliably, and it can only do that within a range.
What the spec actually says
The ranges below come from specific documents. Your model's guide may differ.
| Appliance | Document | Stated range |
|---|---|---|
| Top-load washer | Whirlpool installation instructions W10150593A | 5 to 100 psi; 20 to 100 psi for triple-dispenser models |
| Front-load washer (commercial) | Whirlpool CHW9050/CHW9060 instructions | 20 to 100 psi |
| Dishwasher | GE GLD6500 installation instructions | 20 to 120 psi, hot water line |
| Dishwasher | Samsung water supply requirements | 20 to 120 psi |
| Dishwasher | Bosch SHE53T56UC spec sheet | 14 psi minimum listed |
| Refrigerator | Whirlpool water pressure page | 30 to 120 psi; best at 40 to 80 psi |
| Undercounter ice maker | Sub-Zero 15-inch installation guide | 35 to 80 psi |
Samsung adds a reason in its own words: a water pressure below 20 psi may lead to the failure of the water supply valve and keep it from shutting off properly. Whirlpool's top-load washer guide notes that triple-dispenser washers require 20 to 100 psi for best performance, and Whirlpool's refrigerator page gives the 30 to 120 psi range.
Notice that refrigerators and ice makers tend to need more minimum pressure than washers, and that the ice maker's top limit is lower than a dishwasher's.
Why manufacturers require it
- •Valves need pressure to close. Many inlet valves use water pressure to help seat the valve. Too little, and a valve may not shut off fully.
- •Fills are often timed or measured. Low pressure stretches fill times, and some machines flag a slow fill as an error.
- •Dispensers depend on flow. In a washer, weak flow may not flush the detergent and softener compartments completely.
- •High pressure strains connections. Hoses, valves and fittings take more stress above their rating.
How to check your home against it
- Buy or borrow a water pressure gauge that threads onto a hose bib or a laundry faucet.
- With no water running in the house, thread it on and open the faucet. That's your static pressure.
- Have someone run a shower or kitchen faucet and read the gauge again. A big drop points to restrictions in the piping.
- If your home is on a private well, watch the gauge for several minutes while water runs. Well systems cycle between a low and a high pressure, and the low point is the one that matters.
- Compare your lowest reading with the strictest appliance in the table, usually the refrigerator or ice maker.
- If readings are high, look near the main shutoff for a pressure-reducing valve and note whether one is there.
What happens when it's ignored
- •Washers and dishwashers fill slowly, run long or show fill errors.
- •An inlet valve may not close fully at low pressure and can let water seep into the machine.
- •Ice makers make small or hollow cubes, especially when the supply comes through extra filters. See refrigerator reverse osmosis water pressure for that case.
- •Hoses and valves wear faster when house pressure runs above their range.
When it needs a licensed pro
- •Installing, adjusting or replacing a pressure-reducing valve is plumbing work.
- •A well pump, pressure switch or pressure tank needs a plumber or well contractor.
- •Re-piping a restricted line, such as an old galvanized run, is a job for a plumber.
- •If a reading is far outside the ranges, Whirlpool's refrigerator page suggests having a licensed, qualified plumber test the pressure.
Sources
- •Samsung: Dishwasher water supply requirements (20 to 120 psi; valve failure below 20 psi)
- •Whirlpool: Top-load washer installation instructions W10150593A (5 to 100 psi; 20 to 100 psi for triple dispensers)
- •Whirlpool: Ensuring Correct Water Pressure (refrigerators, 30 to 120 psi)
Table figures also come from the Whirlpool CHW9050/CHW9060 installation instructions, the GE GLD6500 dishwasher installation instructions, the Bosch SHE53T56UC spec sheet and the Sub-Zero undercounter ice maker installation guide, each linked in the posts on those appliances.
Quick check: One gauge reading at a laundry faucet, taken while another tap runs, tells you more than any symptom.
When pressure is in range and a washer or dishwasher still fills poorly, the inlet valve or its screen is the next place to look. Start with our washer repair page, or call TrueFix Long Island at (631) 985-3690.