Short answer
To clean windows without streaks, work on a dull day or when the glass is in shade, use warm water with only a small amount of washing-up liquid, and remove the water with a squeegee in overlapping strokes, wiping the blade after each one. Finish the edges with a dry microfibre cloth. Most streaks come from too much product, dirty water or glass drying too fast in the sun.
Why windows streak
Streaks are residue left behind on the glass. The usual causes are using too much cleaning product, washing with water that has become dirty, wiping with a cloth that spreads grease rather than lifting it, and cleaning in direct sunshine, where the water dries before you can remove it. Hard tap water can also leave faint mineral marks as it dries.
Fix those causes and the right technique does the rest. You do not need special products.
What you will need
A bucket of warm water with a small squirt of washing-up liquid, a window washer or sponge, a squeegee with a clean, undamaged rubber blade, a couple of lint-free microfibre cloths, and an old towel for the sill. Some people prefer a diluted white vinegar solution instead of washing-up liquid; if you use it, keep it off natural stone sills and do not mix it with other products.
Step by step
- Choose a time when the window is out of direct sunlight.
- Brush or vacuum dust and cobwebs from the frame and sill first, so they do not end up on the glass.
- Wash the glass with the soapy water and window washer or sponge, scrubbing any spots or droppings until they lift.
- Wipe a narrow dry strip down one edge of the glass with your cloth, so the squeegee has a dry starting point.
- Pull the squeegee across or down the glass in steady strokes, overlapping each stroke slightly with the one before.
- Wipe the squeegee blade with a cloth after every stroke, so dirty water is not dragged back across clean glass.
- Dry the edges and corners with a clean microfibre cloth, and wipe the sill.
- Check the glass from an angle and buff any remaining marks with a dry cloth.
Inside versus outside
Inside glass is usually greasier and less dusty, so it needs less water. A barely damp microfibre cloth followed by a dry one often works well, and keeps water off internal sills and furniture. If you are unsure whether a streak is inside or outside, wipe inside horizontally and outside vertically; the direction of any streak will tell you which side it is on.
Change the water as soon as it looks dirty, and wash microfibre cloths without fabric conditioner, which leaves a coating that causes smears.
Frames, sills and seals
Clean frames before glass, not after. Our guide to cleaning uPVC covers frames, sills and the drainage slots at the bottom of windows, which are easy to forget.
Upstairs windows and safety
Many modern windows tilt or open inwards so the outside can be cleaned from inside the room. If yours do not, do not lean out of upstairs windows or stand on sills. Ladders against a house wall carry real risk, especially with a bucket in one hand, and are best avoided for windows above the ground floor.
Window cleaners commonly use water-fed poles for higher windows. These are long, lightweight poles with a soft brush at the top, through which purified water is pumped. Because the water contains no minerals, it dries clear without needing a squeegee, and the work is done from the ground.
When to call a professional
It is worth calling a professional for upstairs windows that do not open inwards, for large or hard-to-reach panes, or if you want a regular clean without the effort. A professional can also include frames and sills.
We clean windows for homes across south Essex, outside and inside glass by agreement, with frames and sills included where requested. Tell us about your house and whether you want an occasional visit or a regular clean when you ask for a quote.
Rather have it done for you?
Streak-free windows, frames and sills for homes across Essex. Family-run by Jason and Lucas Prior, covering south Essex.
Frequently asked questions
Why do my windows streak after cleaning?
Usually because of too much product, dirty water, a cloth that spreads grease, or cleaning in direct sun so the glass dries too fast. Use a little washing-up liquid, fresh water and a squeegee in shade.
What is the best thing to clean windows with?
Warm water with a small amount of washing-up liquid, a squeegee with a good rubber blade and a dry microfibre cloth for the edges. You do not need specialist products.
Is vinegar good for cleaning windows?
A diluted white vinegar solution is a popular alternative to washing-up liquid. Keep it off natural stone sills, never mix it with other cleaning products and rinse or buff the glass dry.
Related guides
- How to clean uPVC: getting white uPVC frames, doors, fascias and soffits clean without scratching or dulling the surface.
- Water-fed pole window cleaning explained: what a water-fed pole is, why purified water dries clear without a squeegee, and what it means for frames, sills and upstairs windows.
- How often should windows be cleaned?: why there is no single right interval, and how roads, the coast, trees and the type of building decide how often your windows need cleaning.
- What affects the cost of window cleaning: the factors that change a window cleaning quote for homes and businesses, what a good quote includes and how to compare quotes.