--- title: How to Clear Blocked Window Drainage Holes description: How to clear blocked window drainage holes so water escapes properly. Find the weep slots, clean them safely, and stop leaks and pooling in your uPVC frames. --- [![SM\_Logo\_Final\_Lught](https://smwindowsanddoors.co.uk/hs-fs/hubfs/SM_Logo_Final_Lught.webp?width=140&height=80&name=SM_Logo_Final_Lught.webp "SM_Logo_Final_Lught")](https://smwindowsanddoors.co.uk) - About - [About](https://smwindowsanddoors.co.uk/about) - Doors - [uPVC Doors](https://smwindowsanddoors.co.uk/upvc-doors-york) - [Sliding & Bifold Doors](https://smwindowsanddoors.co.uk/aluminium-sliding-bi-fold-doors) - [Composite Doors](https://smwindowsanddoors.co.uk/composite-doors-york) - [Heritage Aluminium Doors](https://smwindowsanddoors.co.uk/heritage-aluminium-windows-doors) - [Door Repairs](https://smwindowsanddoors.co.uk/window-door-repairs-york) - Windows - [uPVC Windows](https://smwindowsanddoors.co.uk/upvc-windows-york) - [Casement Windows](https://smwindowsanddoors.co.uk/casement-windows-york) - [Sash Windows](https://smwindowsanddoors.co.uk/sash-windows-york) - [Timber Windows](https://smwindowsanddoors.co.uk/timber-windows-york) - [Heritage Aluminium Windows](https://smwindowsanddoors.co.uk/heritage-aluminium-windows-doors) - [Lanterns & Roof Lights](https://smwindowsanddoors.co.uk/korniche-lanterns-flat-roof-lights) - [Window Repairs](https://smwindowsanddoors.co.uk/window-door-repairs-york) - Conservatories - [Conservatories](https://smwindowsanddoors.co.uk/conservatories-orangeries-york) - [Orangeries](https://smwindowsanddoors.co.uk/conservatories-orangeries-york) - Resources - [Gallery](https://smwindowsanddoors.co.uk/gallery) - [Brochures](https://smwindowsanddoors.co.uk/brochure-downloads) - [Blog](https://smwindowsanddoors.co.uk/blog) - [Reviews](https://smwindowsanddoors.co.uk/customer-reviews) - [Contact Us](https://smwindowsanddoors.co.uk/contact) [Request A Quote](https://smwindowsanddoors.co.uk/request-a-quote) [![SM\_Logo\_Final\_Lught](https://smwindowsanddoors.co.uk/hs-fs/hubfs/SM_Logo_Final_Lught.webp?width=140&height=80&name=SM_Logo_Final_Lught.webp "SM_Logo_Final_Lught")](https://smwindowsanddoors.co.uk) [Request A Quote](https://smwindowsanddoors.co.uk/request-a-quote) - About - [About](https://smwindowsanddoors.co.uk/about) - Doors - [uPVC Doors](https://smwindowsanddoors.co.uk/upvc-doors-york) - [Sliding & Bifold Doors](https://smwindowsanddoors.co.uk/aluminium-sliding-bi-fold-doors) - [Composite Doors](https://smwindowsanddoors.co.uk/composite-doors-york) - [Heritage Aluminium Doors](https://smwindowsanddoors.co.uk/heritage-aluminium-windows-doors) - [Door Repairs](https://smwindowsanddoors.co.uk/window-door-repairs-york) - Windows - [uPVC Windows](https://smwindowsanddoors.co.uk/upvc-windows-york) - [Casement Windows](https://smwindowsanddoors.co.uk/casement-windows-york) - [Sash Windows](https://smwindowsanddoors.co.uk/sash-windows-york) - [Timber Windows](https://smwindowsanddoors.co.uk/timber-windows-york) - [Heritage Aluminium Windows](https://smwindowsanddoors.co.uk/heritage-aluminium-windows-doors) - [Lanterns & Roof Lights](https://smwindowsanddoors.co.uk/korniche-lanterns-flat-roof-lights) - [Window Repairs](https://smwindowsanddoors.co.uk/window-door-repairs-york) - Conservatories - [Conservatories](https://smwindowsanddoors.co.uk/conservatories-orangeries-york) - [Orangeries](https://smwindowsanddoors.co.uk/conservatories-orangeries-york) - Resources - [Gallery](https://smwindowsanddoors.co.uk/gallery) - [Brochures](https://smwindowsanddoors.co.uk/brochure-downloads) - [Blog](https://smwindowsanddoors.co.uk/blog) - [Reviews](https://smwindowsanddoors.co.uk/customer-reviews) - [Contact Us](https://smwindowsanddoors.co.uk/contact) [Repairs & Maintenance](https://smwindowsanddoors.co.uk/blog/tag/repairs-maintenance) # How to Clear Blocked Window Drainage Holes By [SM Windows & Doors](https://smwindowsanddoors.co.uk/blog/author/sm-windows-doors) Oct 30, 2026, 9:30:00 AM 3 Minutes Read Water sitting in the bottom of a window frame, or trickling onto the sill indoors, usually comes down to one thing: blocked drainage holes. Those little slots along the bottom of uPVC frames are meant to let rainwater escape, and when they clog up the water has nowhere to go. The good news is that clearing them is a straightforward job most people can do themselves. Here is how. ## What window drainage holes do uPVC windows and doors are designed to let a small amount of water in during heavy rain, then channel it safely back out. The drainage holes, sometimes called weep slots, sit along the bottom edge of the outer frame. Rain that gets past the outer seal drains down inside the frame and out through these slots. When they are clear, you never notice them. When they block up with dirt, leaves, dead insects or general grime, water backs up inside the frame. That is when you see pooling on the sill, damp patches, or water creeping indoors. The same design is used on doors, so a new PVC door drainage hole problem shows up in exactly the same way, with water sitting in the threshold rather than draining away. ## How to find the slots Look along the bottom of the outer frame from outside. You are looking for small horizontal slots, often 5 to 10mm wide, sometimes hidden behind a little hinged cover or flap. Most windows have two or more spaced along the bottom. On some designs the cover clicks open, on others it swings on a small hinge. If you cannot see them straight away, run a finger along the base of the frame and you will usually feel them. ## Clearing them safely, step by step You do not need special tools for this. Work gently so you do not damage the frame or seals: 1. **Clean the outside of the frame first** with warm soapy water, so loose dirt does not get pushed into the slot. 2. **Open any cover flap** over the drainage hole. 3. **Push out the blockage** with something thin and soft, like a cotton bud, a plastic cable tie or a soft brush. Avoid anything sharp or metal that could scratch or gouge. 4. **Flush it through.** Pour a little clean water into the frame track from inside the slot area and watch it run out the bottom. If it drains freely, you are done. 5. **Wipe up** and close any covers back over the slots. If water still will not drain after clearing the visible slot, the channel inside the frame may be blocked further along, which sometimes needs a professional look. ## Why keeping them clear matters Blocked drainage is not just about a bit of standing water. Over time it can lead to: - Water leaking onto sills and into the room - Damp and mould around the frame and reveal - Trapped water freezing and stressing the frame in winter - Premature wear on seals and hardware A two-minute clean a couple of times a year avoids all of it. It is one of the easiest bits of window and door upkeep there is. ## When to call a professional Clearing a slot is a DIY job. Call in help when the problem runs deeper: - Water still pools after the slots are clear, suggesting a blockage or fault inside the frame - The frame is cracked or the drainage channel is damaged - Leaks are coming from the glazing or seals rather than the drainage - Water is getting behind the frame into the wall These point to a repair rather than a clean, and our [window and door repair team in York](https://smwindowsanddoors.co.uk/window-door-repairs-york) can trace where the water is really getting in. If you are choosing new windows or doors, well-made frames with good drainage make all the difference, and our [uPVC windows in York](https://smwindowsanddoors.co.uk/upvc-windows-york) and [uPVC doors in York](https://smwindowsanddoors.co.uk/upvc-doors-york) ranges are built with proper weep drainage as standard. ## FAQs ### Where are the drainage holes on a uPVC window? They are the small slots along the bottom of the outer frame, sometimes behind a little hinged cover. Most windows have two or more spaced along the base. ### What can I use to clear a blocked weep hole? Something thin and soft, like a cotton bud, a plastic cable tie or a soft brush. Avoid sharp or metal tools, which can scratch the frame or damage the seals. ### Why is water coming into my house through the window? The most common cause is blocked drainage holes, so water backs up inside the frame instead of draining out. If clearing them does not fix it, worn seals or glazing may be to blame. ### How often should I clean window drainage holes? A quick check and clean twice a year is usually plenty, ideally in autumn before the wet weather and again in spring. Homes near trees may need it a little more often. Want to see the full range of window and door styles? [Download our latest brochure](https://smwindowsanddoors.co.uk/brochure-downloads), or [request a free quote](https://smwindowsanddoors.co.uk/request-a-quote) and we will come and take a look. #### SM Windows & Doors Author ## Phone: 07833387823 Email: [Sam@smwindowsanddoors.co.uk](mailto:Sam@smwindowsanddoors.co.uk) Opening times: Mon - Fri: 09:00 - 17:00 Sat-Sun: By Prior Appointment [Follow us on Facebook](https://www.facebook.com/people/SM-Windows-Doors/100093013267883/) [Follow us on Instagram](https://www.instagram.com/smwindowsanddoors/) ![x59dcc190ea7d320001f0083a\_logoAsset-2-1.jpg.pagespeed.ic.lk8k-280iY](https://smwindowsanddoors.co.uk/hs-fs/hubfs/x59dcc190ea7d320001f0083a_logoAsset-2-1.jpg.pagespeed.ic.lk8k-280iY.jpg?width=300&height=106&name=x59dcc190ea7d320001f0083a_logoAsset-2-1.jpg.pagespeed.ic.lk8k-280iY.jpg "x59dcc190ea7d320001f0083a_logoAsset-2-1.jpg.pagespeed.ic.lk8k-280iY") ```json { "@context" : "https://schema.org", "@type" : "BlogPosting", "author" : { "@type" : "Person", "name" : "SM Windows & Doors", "url" : "https://smwindowsanddoors.co.uk/blog/author/sm-windows-doors" }, "dateModified" : "2026-10-30T09:30:00.808Z", "datePublished" : "2026-10-30T09:30:00.000Z", "headline" : "How to Clear Blocked Window Drainage Holes", "mainEntityOfPage" : { "@id" : "https://smwindowsanddoors.co.uk/blog/sm-windows-doors-blog/how-to-clear-blocked-window-drainage-holes", "@type" : "WebPage" }, "publisher" : { "@type" : "Organization", "logo" : { "@type" : "ImageObject", "url" : "https://smwindowsanddoors.co.uk/hubfs/SM_Logo_Final_Lught.webp" }, "name" : "SM Windows & Doors" } } ```