Why You Should Never Store Water Inside a Pressure Washer
After you've finished cleaning, it can be tempting to simply switch your pressure washer off and put it away until next time. However, storing a pressure washer with water still inside is one of the biggest causes of avoidable damage.
Water trapped inside the pump, hose, trigger gun and lance can lead to corrosion, damaged seals and, during cold weather, expensive frost damage.
Fortunately, preventing these problems only takes a few minutes after each use.
In this guide, we'll explain why you should never store water inside a pressure washer and how to protect your machine properly.
Why Is Water Left Inside a Pressure Washer a Problem?
Although pressure washers are designed to use water, they are not designed to be stored with water trapped inside them.
Residual water can cause problems including:
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Frost damage
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Corrosion
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Damaged seals
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Pump wear
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Mineral deposits
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Blocked nozzles
Removing water before storage helps keep the entire system in good condition.
Frost Damage
The biggest risk comes during cold weather.
As water freezes, it expands.
Even a small amount of trapped water can crack:
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Pump housing
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Internal valves
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Plastic connectors
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Trigger guns
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Spray lances
Many pressure washer pumps fail because water was left inside over winter.
Internal Corrosion
Although many pressure washer components are corrosion-resistant, standing water can still encourage corrosion inside metal parts over time.
This is particularly important if the machine is stored for several months between uses.
Damaged O-Rings and Seals
Rubber seals remain in constant contact with trapped water.
Over time this can contribute to:
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Seal deterioration
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Water leaks
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Reduced pressure
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Difficult connections
Allowing the system to dry helps extend the life of these components.
Mineral Deposits
In hard water areas, trapped water can leave behind mineral deposits.
Limescale may build up inside:
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Pump passages
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Spray nozzles
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Valves
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Connectors
Over time this can reduce pressure and affect cleaning performance.
Blocked Nozzles
As trapped water dries, minerals and debris can accumulate inside the nozzle.
This may lead to:
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Uneven spray pattern
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Low pressure
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Pulsing
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Poor cleaning performance
Flushing the machine after use helps reduce this risk.
Stale Water
If water remains inside the machine for long periods, it can become stagnant.
This may encourage the build-up of:
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Dirt
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Algae
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Organic deposits
Keeping the system clean helps maintain reliable operation.
How to Remove Water Before Storage
After finishing your cleaning:
Step 1
Turn off the water supply.
Step 2
Disconnect the garden hose.
Step 3
Squeeze the trigger gun.
Allow any remaining water pressure to escape.
Step 4
Disconnect the high-pressure hose.
Drain all remaining water.
Step 5
Remove the spray lance and allow any trapped water to drain out.
Step 6
Store the pressure washer in a clean, dry and frost-free location.
Should You Empty the Pump?
Yes.
The pump is the most important part of the pressure washer.
If recommended by the manufacturer, briefly operating the machine for one or two seconds after disconnecting the water supply can help remove the last traces of water.
Do not allow the pump to run dry for more than a second or two, as this can damage internal components.
Always follow the manufacturer's instructions for your specific model.
Should You Use Pump Protector?
Many manufacturers recommend using a pressure washer pump protector before long-term storage.
These products can help:
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Protect internal seals
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Reduce corrosion
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Prevent freezing
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Extend pump life
They are particularly useful if the pressure washer will not be used for several months.
Common Mistakes
Leaving Water in the Hose
Even if the pressure washer has been drained, water inside the hose can freeze and cause damage.
Always empty the hose completely.
Forgetting the Trigger Gun
The trigger gun also traps water.
Allow it to drain before storage.
Ignoring the Spray Lance
Lances and nozzles often retain small amounts of water.
Drain them separately before putting them away.
Storing the Machine Outdoors
Even under a waterproof cover, freezing temperatures can still damage the machine.
Whenever possible, store your pressure washer indoors.
What Happens If You Forget?
If water has been left inside the pressure washer and the machine has been exposed to freezing temperatures, inspect it carefully before using it again.
Check for:
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Water leaks
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Cracked plastic components
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Split hoses
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Reduced pressure
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Unusual pump noises
Do not continue using the pressure washer if significant leaks are present.
How This Relates to Other Pressure Washer Problems
Storing water inside the machine can contribute to several common faults.
For example:
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If your pressure washer is leaking water, see Pressure Washer Leaking Water? Causes and Fixes
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If pressure is low, read Pressure Washer Has Low Pressure? Causes and Fixes
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If the machine won't build pressure, see Pressure Washer Won't Build Pressure? Causes and Fixes
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If your pressure washer won't start after storage, see Pressure Washer Won't Start? Causes and Fixes
Replacement Parts After Frost Damage
If trapped water has caused damage, common replacement parts include:
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High-pressure hoses
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Trigger guns
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Spray lances
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O-rings
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Seal kits
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Water inlet filters
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Pump components
Replacing damaged parts can often restore the pressure washer without replacing the entire machine.
You can find replacement pressure washer parts and accessories for many popular brands, including Kärcher, Nilfisk, Bosch, Makita and more, from Yourspares.
Final Thoughts
Leaving water inside a pressure washer after use may seem harmless, but it can lead to corrosion, blocked components, damaged seals and expensive frost damage.
By taking a few minutes to drain the pump, hose and accessories before storage, you can help extend the life of your pressure washer, maintain its performance and avoid unnecessary repair costs.
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