Being able to see clearly through your windscreen is one of the most fundamental parts of safe driving. In Ireland's wet climate — where rain, road spray, mud and grime are a daily reality — your windscreen washer system and wiper blades are among the most frequently used safety systems on the car. The RSA Rules of the Road requires windscreen wipers and washers to be in good working condition at all times, and specifically checks them as secondary controls on the driving test.
Vehicle Safety & Pre-Drive Checks — Article Series
In This Guide
Why Washers and Wipers Matter
A dirty or smeared windscreen does not just cause irritation — it is a serious visibility hazard. Sunlight hitting a smeared screen can cause temporary blindness. Road spray from a lorry in wet conditions can obscure the windscreen in seconds. At 80 km/h, the time between a wiper stroke matters.
The RSA Rules of the Road states explicitly: "Keep your windscreen wipers and wiper blades in good working condition and keep your windscreen washer liquid topped up." And: "Keep your windscreen and windows clean and free of clutter to make sure you can see the road and other road users clearly."
Both requirements are part of the legal obligation to drive a roadworthy vehicle. Worn blades, empty washer bottles and blocked jets are all preventable — and all can be identified in a five-minute check.
What to Check
A complete windscreen check covers seven elements:
- Washer fluid level — is the reservoir topped up?
- Washer spray — does fluid actually reach the windscreen?
- Jet alignment — are the jets aimed at the correct area of the screen?
- Front wiper blades — are they clearing glass cleanly without streaks?
- Wiper speed settings — do all speeds (slow, fast, intermittent) work?
- Rear wiper and washer (if fitted) — are both working?
- Demisters — are front and rear demisters clearing the glass?
12-Step Check Routine
Park on level ground in daylight if possible. Look at the windscreen from outside first — check for cracks, chips, significant smearing or any obstruction. A cracked windscreen may not be accepted for your driving test.
The windscreen washer reservoir is a translucent plastic tank, usually marked with a windscreen symbol (a rectangle with lines and a wiper arc). Locate it in your specific car — position varies by model.
Most reservoirs are translucent so you can see the level without opening the cap. If the level is below half — top it up. Do not leave it until it is empty. In Ireland's wet and dirty driving conditions, a full reservoir can last less than two weeks in heavy use.
Add screen wash concentrate mixed with water at the correct concentration for the season (see section below). Do not use engine coolant, antifreeze or washing-up liquid in the washer bottle — these can damage the system, block the jets and strip paint from the bodywork.
The wipers and washers require the ignition to be on to test. You do not need to start the engine — just turn the key or press the start button to the "on" position without starting.
Pull the washer stalk or press the washer button. Fluid should spray onto the windscreen in the wiper sweep area. If there is no spray, or it is very weak, check fluid level first, then check for blocked jets. If jets spray onto the bonnet or roof, they need re-aligning (see section below).
Switch through slow speed, fast speed and intermittent mode. Watch the blades carefully — they should sweep smoothly and clear the glass without leaving streaks, missing sections or chattering. Any of these symptoms indicate worn or damaged blades.
Lift each wiper arm away from the glass and run your finger along the rubber blade edge. It should feel smooth and pliable. Splits, cracks, stiffness, or sections where the rubber has separated from the frame all mean the blade needs replacing.
Activate the rear wiper and washer. The rear wiper should sweep smoothly and the spray should reach the rear screen. The RSA requires all window cleaning equipment to be checked and operational.
Switch on the front heater blower and check that warm air reaches the windscreen area. The front demister clears condensation that washer fluid and wipers cannot deal with. Know where the demister control is in your specific test car.
Switch on the rear window heater (usually a button showing horizontal lines on a rectangle). Confirm the indicator light comes on. On a cold, misted morning, you can verify it is working by feeling the rear screen warm up within a minute.
Look through the cleaned windscreen. Your view forward should be completely clear. Also check both side windows and the rear screen. Any smearing, fogging or obstruction that remains after the wiper and demister check needs to be addressed before driving.
Screen Wash vs Plain Water
One of the most common and easily avoided problems Irish drivers encounter — particularly in winter — is a frozen or ineffective washer system caused by using plain water.
Wiper Blade Condition Guide
Wiper blades degrade over time from UV exposure, heat, cold and repeated use. In Ireland's variable climate, blades typically need replacing at least once a year — many drivers replace them more often.
✓ Good Condition
Sweeps cleanly. No streaks. Rubber soft and pliable. No splits or cracks. Full contact across the blade width.
⚠ Marginal — Replace Soon
Light streaking on one side. Slight chattering at low speed. Rubber beginning to harden. Visible minor cracking.
❌ Replace Immediately
Heavy streaking or missed sections. Loud squeak or judder. Rubber split, cracked or lifting away from frame. Fails to clear properly in rain.
- At least every 12 months as a standard routine
- As soon as streaking, chattering or squeaking begins — do not wait for complete failure
- Before winter — worn blades struggle most in heavy Irish rain and road spray
- Always replace in pairs — if one blade is worn, the other is likely close behind
Checking Washer Jet Direction
Washer jets should spray fluid into the area swept by the wiper blades — typically the central portion of the windscreen. Misaligned jets spray onto the bonnet, the roof or the A-pillars, wasting fluid and leaving the windscreen uncleared.
How to re-align washer jets: use a pin, sewing needle or unfolded paperclip. Insert it carefully into the small hole at the centre of the jet nozzle. Rotate or tilt gently to redirect the spray. The jet ball-joint has a wide range of motion. Test after each small adjustment.
Wipers and washers checked in EDT Session 1
BP Driving School walks you through every secondary control — wipers, washers, demisters — from your very first lesson. RSA-approved, North Dublin.
Winter Tips for Irish Roads
Ireland's winter driving conditions are among the most demanding on windscreen systems — frequent rain, frost, road salt and early darkness all increase the workload on wipers and washers significantly.
- Switch to a higher-concentration screen wash mix in October — a 50/50 concentrate/water ratio protects to approximately -15°C
- Never pour boiling water on a frozen windscreen — it can crack the glass. Use a de-icer spray and a scraper
- Lift wiper blades away from the glass overnight in frost — blades frozen to the screen can tear when operated
- Check washer fluid more frequently in winter — salt and mud spray from other vehicles depletes it much faster
- Ensure the rear window heater is working before winter — it is your primary tool for clearing a fogged rear screen in the morning
Before the RSA Driving Test
The RSA driving test assesses wipers and washers under two categories:
- Technical checks — you must show where the washer reservoir is and explain how to top it up
- Secondary controls — the examiner will ask you to operate the wipers (all speeds), front washer, rear wiper and washer (if fitted), front demister and rear window heater
- Washer reservoir level — at least half full
- Washer spray reaching the swept area on both front and rear
- Wiper blades clearing cleanly at all speeds — no streaking
- Rear wiper and washer operating (if your car has them)
- Front and rear demisters working
- Windscreen clean — inside and outside
Common Problems to Watch For
Empty washer bottle
The most common issue — entirely preventable with a monthly check. Running out mid-drive is frustrating; running out on test day is worse. Keep the reservoir at least half full and carry a small bottle of screen wash concentrate in the car.
No spray or very weak spray
Check fluid level first. If the bottle is full and there is still no spray, check for a blocked jet (see jet alignment section) or a failed washer pump. A failed pump typically makes a buzzing sound but produces no fluid — this requires professional repair.
Wiper blades leaving streaks
Usually means the rubber is worn, hardened or contaminated. Try cleaning the blade edge and the glass with a damp cloth first — sometimes debris on the blade causes temporary streaking. If it persists, replace the blades. Streaking is a common driving test fault.
Wipers chattering or juddering
Worn or hardened rubber, a bent wiper arm that has lost its downward tension, or a very dirty windscreen. Clean the glass first. If the wiper arm is bent, it needs adjusting — a garage or motor factor can do this quickly.
Frozen washer system in winter
Caused by using plain water or an insufficiently concentrated screen wash mix. The reservoir, pipes and jets can all freeze, blocking the system entirely. Switch to winter-strength screen wash in autumn — do not wait for the first frost.
Wipers not parking at the bottom of the windscreen
If wipers stop mid-screen or do not return to the rest position, the wiper motor or linkage may be failing. This is a mechanical fault that requires professional attention.
Frequently Asked Questions
More from the Vehicle Safety & Pre-Drive Checks series
Your first EDT lesson with BP Driving School covers every secondary control — including wipers, washers and demisters — exactly as the examiner requires. Book your EDT course — RSA-approved, Swords, North Dublin.
Nearly test-ready? Book a mock test to rehearse the full secondary controls check with a qualified ADI.