Can I use plain water instead of windscreen washer fluid?

Plain water may work temporarily in mild weather, but proper washer fluid cleans better and may provide freeze protection. In freezing conditions, water can freeze in the reservoir, hoses or jets, so use a washer fluid rated for the expected temperature.

Can I mix different windscreen washer fluids?

Some washer fluids are compatible, but formulations vary. Check the product label and vehicle manual. If you are unsure what is already in the reservoir, use a compatible ready-mixed product or follow the manufacturer's guidance rather than mixing products blindly.

How full should the washer-fluid reservoir be?

Fill only to the level or limit specified by the vehicle manufacturer. Some reservoirs have a visible level mark while others do not, so check the owner's manual rather than forcing in more fluid once the reservoir appears full.

What if I accidentally put washer fluid in the wrong reservoir?

Do not start or drive the vehicle. Avoid operating the affected system and arrange for the incorrect fluid to be removed according to the vehicle manufacturer's guidance. Contamination of brake fluid, coolant, engine oil or other systems can cause serious problems.

Why does no washer fluid come out after I refill it?

Possible causes include frozen fluid, blocked jets, a disconnected or leaking hose, a failed pump or an electrical fault. If the pump runs but no fluid appears, avoid repeatedly running it dry and inspect the system for leaks or blockages.

Guides/Automotive/How to Top Up Windscreen Washer Fluid

How to Top Up Windscreen Washer Fluid

Top up your car's windscreen washer fluid safely, choose a washer fluid suitable for the season and avoid common mistakes such as using the wrong reservoir or relying on plain water in freezing conditions.

Updated Oct 22, 2026

10 min6 stepsBeginnernew

What you need

Tick off what you already have.

Tools

Clean funnel, optional
Disposable gloves, optional

Materials

Windscreen washer fluid suitable for the vehicle and season

Car owner's manual beside a container of suitable windscreen washer fluid

AI illustration

Step 01 / 06

Check the manual and choose the right washer fluid

Read the owner's manual before starting so you know the reservoir location and any fluid requirements. Use windscreen washer fluid suitable for the vehicle, climate and expected temperatures. If using a concentrate, dilute it exactly as its label specifies. In freezing conditions, do not rely on plain water because it can freeze in the reservoir, hoses or jets.

Guide progress1 / 6

1. Check the manual and choose the right washer fluid
Instructional illustration generated with AI for Howmigo.
Read the owner's manual before starting so you know the reservoir location and any fluid requirements. Use windscreen washer fluid suitable for the vehicle, climate and expected temperatures. If using a concentrate, dilute it exactly as its label specifies. In freezing conditions, do not rely on plain water because it can freeze in the reservoir, hoses or jets.
2. Park safely and switch the vehicle off
Instructional illustration generated with AI for Howmigo.
Park on a stable, level surface, apply the parking brake and switch the vehicle fully off. Let hot under-bonnet components cool if necessary before reaching into the engine bay. Secure the bonnet according to the vehicle instructions. If you also want to check the engine oil on a car equipped with a dipstick, see how to check the engine oil level.
3. Identify the washer-fluid reservoir
Instructional illustration generated with AI for Howmigo.
Locate the windscreen washer-fluid reservoir using the owner's manual and its washer/windscreen symbol. Do not identify it by cap colour alone, because colours vary between vehicles. Before opening anything, make sure you have not selected the coolant, brake-fluid, power-steering or engine-oil reservoir.
4. Open the reservoir carefully
Instructional illustration generated with AI for Howmigo.
Clean away loose dirt around the washer-fluid cap so contamination does not fall inside. Open the cap as designed and keep it clean. If the reservoir or filler neck is damaged, or you are not certain it is the washer reservoir, stop and verify it before adding fluid.
5. Add washer fluid without overfilling
Instructional illustration generated with AI for Howmigo.
Pour the prepared washer fluid slowly into the reservoir, using a clean funnel if helpful. Fill only to the level or limit specified by the vehicle manufacturer; if there is no visible marking, follow the owner's manual rather than forcing in more fluid. Wipe up spills promptly.
6. Close the cap and test the washers
Instructional illustration generated with AI for Howmigo.
Refit the reservoir cap securely, remove tools and containers from the engine bay and close the bonnet properly. Start the vehicle as required and briefly operate the windscreen washers. Confirm that fluid reaches the windscreen and the wipers clear it normally. If the pump runs but no fluid appears, or fluid leaks under the car, inspect the system rather than repeatedly operating a dry or blocked pump.